Spring 2024

GREENSCAPE 

Ensuring Best Practice for Green Roof & Solar PV Projects MAGAZINE 

SPRING 2024 

GRO at Futurebuild 

Academic Growing Corner 

crops 

Blue Roofs 

Green Roofs: Fire Safety 

#WGRD2024 is coming! 

PV: Commercial Roofs 

In collaboration with the Green Roof Organisation

GeoShield 

New Build: 3rd Party Integrity Testing Services 

All Weather Electronic Leak Detection 

Green Roof/Blue Roof/Buried & Podium Decks – 

Latent Defects Policy Support 

Are you complying with your roof deck warranty providers requirements? 

At GeoShield - Verification Programs for Ground Gas Protection, 

Waterproofing & Roof Decks - we carry out Electronic Test Methods (ELD) as 

per those advised by the Roof and Waterproofing Test Association. 

Flat Roofs 

Podium Decks 

Buried Decks 

Balconies 

Cold Roofs 

Green Roofs 

Blue Roofs 

Warm Roofs 

Rapid Response 

Team Available 

Upon Request 

www.geoshield.co.uk • info@geoshield.co.uk • 0113 3208639 •

GREENSCAPE 

IN THIS ISSUE... 

Matt Downs 

Editorial Director 

mattdowns@media-now.co.uk 

07963 330774 

www.greenscapemag.co.uk 

The crucial role of green roofs and associated systems in reducing the impact of 

climate change and biodiversity challenges in the built environment continues 

to gain momentum. February saw the implementation of the Government’s 

Biodoversity Net Gain (BNG) policy, an approach to development that aims to leave the 

natural environment in a measurably better condition than it was prior to construction work 

taking place. Since 12th February, all planning permissions granted in England – with a few 

exemptions – have to deliver at least 10% biodiversity net gain, and this looks set to present 

further opportunities for those operating in the green infrastructure sector. 

Implementing BNG will no doubt be a key topic of conversation on stands and in the 

seminar theatres at this year’s Futurebuild exhibition, which takes place on 5th March at 

ExCeL London. Following huge success at Futurebuild 2023, where its stand was one of the 

top five most visited locations, the Green Roof Organisation returns with its GRO Pavilion, 

where a number of key individuals from GRO member companies and the association will 

be available to answer visitor queries, plus address and debate key sector issues on the 

Sustainable Infrastructure stage. Head to page 18 to find out the topics for GRO’s talks and 

debates, plus to see what else is happening on the GRO Pavilion! 

Elsewhere in this issue, we bring you news of the steps GRO’s Training & Education working 

group is taking to tackle the increased demand for skilled workers in the green roof sector 

(p.08); Dr Tom Young talks all things biochar with Dr Joerg Werdin in his latest Academic 

Corner Q&A (p.10); Optigrun focus on biosolar roofs (p.14); Julian Thurbin of Wallbarn 

addresses fire safety (p.20); and we take a look at an interesting blue roof project in Dublin 

(p.26). Read on for all this and much more! 

Enjoy the issue! 

Front cover: 1,500m 2 of Wallbarn’s M-Tray system was installed 

alongside solar PV at Turing House School in South West London. 

GREENSCAPE 

www.greenscapemag.co.uk 

Advertising: 

Publishing Director: Andy Dunn 

DD: 01892 730 890 

Mob: 07963 330777 

Email: andydunn@media-now.co.uk 

Brought to you by the publishers of Total Contractor, the content 

of Greenscape magazine (and website) does not necessarily 

reflect the views of the editor or publishers and are the views of 

its contributors and advertisers. The digital edition may include 

hyperlinks to third-party content, advertising, or websites, 

provided for the sake of convenience and interest. The publishers 

accept no legal responsibility for loss arising from information in 

this publication and do not endorse any advertising or products 

available from external sources. No part of this publication may 

be reproduced or stored in a retrieval system without the written 

consent of the publishers. All rights reserved. 

Registered office: 

1 Forstal Road, Aylesford, 

Kent, ME20 7AU 

This magazine and its packaging can 

be recycled. 

Supported by: 

CONTRIBUTORS TO THIS ISSUE... 

p 10 

Academic Corner 

Dr Tom 

Young of The 

Environmental 

Partnership (TEP). 

p 20 

Ensuring safe 

green roofs 

Julian Thurbin, 

Director at 

Wallbarn. 

p28 

Commercial PV 

projects 

Chris Cowling 

of Aztec Solar 

Energy. 

Dr Tom Young continues his Academic 

Corner Q&As, this time putting the 

questions to green roof expert Dr Joerg 

Werdin, who has carried out research 

into the use of biochar in green roof 

substrates. 

P 10 

Whilst Julian Thurbin is a strong advocate 

for green roofs and believes they 

should be the norm for domestic and 

commercial properties where possible, 

he says fire performance is one area that 

needs wider consideration 

P 20 

With continued growth in the number of 

commercial buildings installing solar PV 

systems, Chris explains how to get the 

specification and installation correct to 

ensure projects maximise the benefits 

and enjoy long-term success. 

P 28 

www.greenscapemag.co.uk • GREENSCAPE SPRING 2024 3

Contents 

NEWS 

06 The theme for #WGRD2024 is 

Energy, and organisers are urging 

people to get involved by sharing 

videos and taking part in green roof 

tours on June 6th; plus Green-tech 

have announced their plans to support 

customers following the launch of the 

Government’s BNG policy... 

08 Green roofs were given a notable 

mention in the House of Commons 

Environmental Committee’s recent 

report; plus we hear about the GRO 

Training & Education working group’s 

work to improve skills and attract new 

entrants to the sector 

GREEN ROOFS 

20 Whilst Wallbarn’s Julian Thurbin 

says green roofs provide so many 

positives for the built environment, 

but he points out fire performance 

is an area that needs much wider 

consideration... 

24 As demand for green and blue 

roofs continues to grow, Justin 

Pitman of Proteus Waterproofing 

looks at the steps to take to ensure 

projects stand the test of time 

26 We take a closer look at Dublin’s 

‘first ever’ blue roof project which 

involved ACO’s RoofBloxx system 

4 GREENSCAPE SPRING 2024 • www.greenscapemag.co.uk

GREENSCAPE 

SOLAR PV 

09 A YouGov poll shows 79% of 

MPs support making solar panels 

mandatory for all new-build homes, 

with Solar Energy UK stating: 

“Everyone wins from making solar 

power effectively mandatory for 

new housing” 

28 Aztec Solar Energy’s Chris 

Cowling highlights the key 

considerations when specifying and 

installing PV systems on commercial 

properties 

REGULARS 

10 Academic Corner Q&A: Dr Tom 

Young puts the questions to Dr 

Joerg Werdin, a green roof expert 

who has carried out extensive 

research into biochar and its 

suitability for use in green roof 

substrates... 

18 GRO column: Following huge 

success at Futurebuild 2023, the 

GRO Pavilion returns to the ExCeL 

London in March, with the team 

tackling the key sector issues in the 

seminar theatre, and experts from 

GRO member companies and the 

association ready to provide advice 

to visitors on their stand... 


News 

GREENSCAPE 

GREEN-TECH TAKES STEPS TO SUPPORT SUPPLY CHAIN FOLLOWING 

LAUNCH OF GOVERNMENT’S BNG POLICY 

ALL EYES ON THE GREEN ROOF 

SECTOR FOR #WGRD2024 

June 6th has established itself as a key 

date globally in the green roof calendar, 

with the sector and champions of 

green infrastructure coming together 

to celebrate and raise awareness of 

green roofs on World Green Roof Day. 

Launched by green roof experts Chris 

Bridgman and Dusty Gedge, World 

Green Roof Day is now in its fourth 

year, and has reached more than 60 

countries since the inaugural event, 

with individuals and companies from 

Brazil to New Zealand, and Norway to 

South Africa getting involved! 

Discussing this year’s event, Chris 

explained: “Every year World Green 

Roof Day expands its reach, bringing 

together the global green roof sector 

supply chain, and raising awareness of 

green roofs and the crucial role they 

play in reducing the impact of climate 

change and biodiversity challenges 

facing the built environment. 

“This year’s theme is Energy, from 

generating power in combination with 

green roofs, in the form of solar panels 

or wind turbines, to human energy, 

including running, cycling, yoga or even 

food growing and beekeeping. We 

encourage participants to share case 

studies, ideas, videos and photos on 

World Green Roof Day using hashtag 

#WGRD2024. 

“We’ve seen over 62 countries join 

the celebrations to date, showcasing 

projects, sharing green roof stories 

across social media, and hosting inperson 

events and rooftop tours. We’re 

sure #WGRD2024 will be the biggest 

yet!” Get involved on June 6th: 

www.worldgreenroofday.com 

The Government’s 

much anticipated 

Biodiversity Net 

Gain (BNG) policy 

became effective 

on 12th February. 

The BNG policy 

is an approach 

to development, 

and management, 

that aims to 

leave the natural 

environment in a measurably better state 

than it was before construction took place. 

Following the launch of the policy, 

residential developments with 10 or 

more dwellings, or where the site area 

is greater than 0.5 hectares, will have to 

deliver net gains for biodiversity leading 

to positive outcomes for nature, better 

places for local communities, and more 

consistent and transparent requirements 

for developers. 

Under mandatory BNG, all developments 

in England must replace any biodiversity 

lost and add a minimum of 10% 

biodiversity to provide a net gain. The 

resulting habitat will be secured for at 

least 30 years via planning obligations or 

conservation covenants, enforced by s106 

agreements. 

With this new BNG focus in mind, the 

team at John Chambers Wildflower Seed, 

a brand of leading landscape supplier 

Green-tech, has worked with Bridgman & 

Bridgman to design a new BNG biodiverse 

green roof mixture. 

Bridgman & Bridgman are specialists in 

the creation of sustainable living roofs, 

and Green-tech says they trialled the 

wildflower seed mix to ascertain the bestperforming 

species. 

Following the trials, the final mixture 

comprises 40 species of native wildflower 

to ensure at least 

25 species are 

present once the 

roof is established, 

to meet the 

new legislation. 

The team at 

John Chambers 

Wildflower Seed 

say the seed 

mix should be 

complemented 

with native sedum 

and dry grassland species as described in 

the guidelines. 

Green-tech Specifier team – L-R: Georgia Gilbert, 

Roger McGivern, Emily Murray, Jason Brits, Mark 

Wood, Sereya Sigworth, Richard Wexham. 

Georgia Gilbert, John Chambers 

Wildflower Seed Technical Manager, 

explained: “The final mix contains native 

wildflower seed to combat the huge 

declines we have seen due to habitat loss, 

chemical use, and climate change. Native 

species are incredibly valuable for our 

native wildlife. We also chose species that 

are suitable and perform well in green 

roof structures – ones that are drought 

tolerant, suitable for full sun and exposed 

conditions, and thrive in lightweight 

substrate.” 

Mark Wood, Green-tech’s Business 

Development Director, added: “Like many 

others in the industry, Green-tech has 

been planning for Biodiversity Net Gain 

and the introduction of the Government’s 

mandatory BNG policy. We have developed 

an interactive Biodiversity Net Gain map 

for use alongside the Biodiversity Metric 

to contribute to different design options, 

in the creation of a Nature Positive design. 

We aim to create a collaborative approach 

with an overview of enabling nature to 

thrive through considerate development. 

Users can view the map at https://www. 

gtspecifier.co.uk/interactive-map/ 

– simply click on the map and they will 

find an abundance of information and 

resources to help ensure their project is 

BNG compliant.” 

www.green-tech.co.uk 


ROOF 

WE’LL 

BRING TO 

YOUR LIFE. 

ROOF 

TO 

Any size. 

Any system. 

LIFE. 

Anywhere. 

Any size. 

Any system. 

Anywhere. 

gardensinthesky.co.uk 

info@gardensinthesky.co.uk 



info@gardensinthesky.co.uk 

info@gardensinthesky.co.uk

News 

GRO WORKING GROUP OUTLINES STEPS IT’S TAKING TO ADDRESS 

SECTOR SKILLS GAP AS DEMAND CONTINUES TO GROW 

GREEN ROOFS REFERENCED IN 

HOUSE OF COMMONS REPORT 

The Green Roof Organisation (GRO) 

says it is delighted to have been 

recognised by the House of Commons 

Environmental Audit Committee in 

their report on ‘Heat Resilience and 

Sustainable Cooling’. 

This comes following much work 

and input from GRO and particularly 

Company Secretary Mark Harris, with 

a key recommendation from this 

report stating: 

Section 36: We recommend that the 

Government take action to expand 

urban green space, particularly in 

disadvantaged areas. At a minimum 

these actions ought to include: 

(i) introducing a statutory requirement 

on local authorities to protect green 

space; 

(ii) mandating local authorities 

in urban areas to use the Green 

Infrastructure Framework; 

(iii) introducing measures to 

incentivise the installation of green 

roofs as new build or retrofit on 

appropriate residential or business 

premises. 

In a statement its website, GRO 

explained: “To be aligned with these 

overarching goals and deliver best 

practice guidance to the industry and 

government is the purpose of Green 

Roof Organisation (GRO) – thank you 

to Mark Harris for enabling this next 

step for GRO.” 

Download the report in the news 

section at: 

www.greenrooforganisation.org 

A number of training courses are in place to ensure skilled workers are coming through 

to meet the ever-increasing demand for green roof projects within the UK. 

According to green roof material 

supplier Diadem, the green roof market 

is set to be worth GBP £4.5 billion 

by 2030. This is based on growth of 

around 17% each year. But how will the 

industry keep up with demand without 

the recruitment of the next generation 

of designers, installers and stewards of 

vegetated rooftops? And how is GRO, 

the Green Roof Organisation, addressing 

the potential skills gap? 

GRO has announced that the recently 

formed GRO Training & Education 

working group is celebrating over 500 

learners that have engaged with green 

roof training via Lantra Awards and GRO 

certification since 2018. GRO says the 

training has been rolled out across the 

four UK nations, including uptake from 

NatureScot, Natural Resources Wales 

and Queen’s University Belfast, plus 

numerous practical installation courses 

in England. 

The association points out its member 

companies Wildflower Turf Ltd and 

Wraxalls have been offering green 

roof training to their partners and 

clients to encourage further uptake 

in the industry, and Construction 

College Midlands, part of Walsall 

College, has created a bespoke green 

roof rig in its green skills training 

area. GRO has also announced this 

year sees the introduction of a Green 

Roofs Microcredential (qualification) 

from Gower College and Swansea 

University, supported by funding from 

Welsh Government and, separately, 

the foundations of a Sustainable 

Environmental Roofing apprenticeship 

scheme. 

GRO says it is also actively working 

towards a more diverse and inclusive 

industry, having signed up to the 

Horticultural Industries ED&I Charter, 

and says it is proud that there is already 

a good ethnic and gender balance 

across the 500 plus certified learners. 

With this in mind, the association points 

out Abigail S. was just 18 when she 

became the first female, and only the 

third person, in the UK to hold a blue 

LISS/CSCS Green Roof Installer card, 

demonstrating competency in the 

installation and maintenance of green 

roofs. 

The working group, which is made up 

of Chris Bridgman as Chair (Bridgman 

& Bridgman and GRO Vice Chair), Giles 

Doland (Zinco and GRO Chair), Mark 

W Harris (SIKA and GRO Secretary), 

Kay Rose (Institute of Roofing), Ben 

Arundel (ABG Installs), Ben Howkins 

(Sky Garden), Mark Dunn (SIKA), Neel 

Bidessie (Langley) and James Beattie 

(Pritchard & Pritchard), says it will 

be focusing on meeting the training 

needs of the future across all learning 

levels, and including all roles within the 

industry, whilst a route map for learners 

will be created, as well as a focus on 

training the trainer. 

www.greenrooforganisation.org / 

www. lantra.co.uk/product/35103 


GREENSCAPE 

YOUGOV POLL SHOWS MPS OVERWHELMINGLY BACK MANDATORY 

SOLAR PANELS FOR NEWBUILD HOMES 

Eight in ten MPs (79%) support 

making solar panels mandatory for all 

new-build homes, according to a new 

YouGov poll. 

Above: Andy Rowlands. 

KEY APPOINTMENMT AT AZTEC 

Aztec Solar Energy Ltd, the nationwide 

engineering-led consultancy and 

installer of bespoke solar photovoltaic 

(PV) systems (BESS), has appointed 

Andy Rowlands in a brand new role as 

Operations Manager. 

Andy will manage and oversee the 

implementation to final delivery of 

projects for Aztec Solar Energy. He 

will have a team of project managers, 

logistics and the design team reporting 

to him. He brings more than 24 years’ 

experience in the electrical industry, of 

which the last three years have been in 

the solar PV sector. 

Talking about his new role, Andy 

said: “It’s great to be joining such a 

rapidly expanding company. Aztec 

Solar Energy are involved in every 

aspect of the business, from design to 

final installation, and is exploring new 

opportunities such as operations and 

maintenance of systems in the future. 

“They can demonstrate their longterm 

commitment and passion for 

solar energy having been in the 

business through both the early days 

and even when FITs stopped. They are 

passionate about renewable energy for 

commercial buildings and are in it for 

the long term.” 

Chris Cowling, commercial director for 

Aztec Solar Energy, said: “Andy brings 

a wealth of knowledge and experience 

with him and is already introducing 

new processes that will help us evolve 

our current business and develop into 

new areas.” 

www.aztecsolarenergy.co.uk 

The findings have been highlighted on 

Solar Energy UK’s website, with the 

association stating the Government 

is consulting on proposals for 

regulations for newbuild homes 

that will come into force in 2025, 

with two options – one to mandate 

solar panels for all new homes, and 

one to not mandate them. 

Solar Energy UK says according to the 

YouGov poll, 79% of all MPs, and 83% 

of Labour MPs, agree that solar panels 

should be incorporated into all newbuilds 

from 2025. 

The trade association points out 

three in five (61%) MPs believe that 

battery storage, which can maximise 

the gains from solar panels, should 

be mandatory in new homes as well, 

and says that figure rises to 77% for 

Labour MPs. 

The poll comes as the Government is 

considering crucial new regulations 

that will set standards for energy 

efficiency, renewable energy, and 

carbon reduction under the Future 

Homes Standard. The Future Homes 

Standard is due to come into force 

from next year. 

Solar Energy UK points out 

campaigners say the new regulations 

present a key opportunity to boost 

renewable energy in the UK and lock in 

low energy bills for homeowners. The 

MCS Foundation, which commissioned 

the YouGov poll, says that MPs’ clear 

support for solar power and battery 

storage shows a recognition that the 

future lies in homes that can generate 

their own clean energy. 

David Cowdrey, Director of External 

Affairs at the MCS Foundation, said: 

“When it comes to constructing 

Above: Marley SolarTIle. Left: 

Chris Hewett, Solar Energy UK. 

modern homes that are 

climate-friendly and cheap to run, 

building-in solar panels, batteries for 

energy storage, and heat pumps from 

the start is very clearly the way to go. 

“It is very encouraging that such 

a clear majority of MPs back the 

principle of renewable energy for all 

new homes. The Government now has 

a mandate to require a meaningful 

deployment of solar panels as well as 

battery storage on new-builds under 

the Future Homes Standard, and it 

must enact that as soon as possible.” 

Chris Hewett, Chief Executive of the 

Solar Energy UK trade association, 

said: “Everyone wins from making 

solar power effectively mandatory 

for new housing. It means lower 

bills for newbuild homeowners and 

greater energy security for us all, plus 

progress towards net zero through 

cutting reliance on pricey natural 

gas. The policy would save newbuild 

homeowners between £910 to £2,120 

per year, according to the Government 

consultation, while pushing purchase 

prices up only marginally.” 

The MCS Foundation is advocating 

that all new homes should have a 

meaningful deployment of solar 

panels, with a suggested consultation 

response that can be filled in easily at: 

mcsfoundation.org.uk/campaigns/ 

future-homes/ 

www.solarenergyuk.org 


ACADEMIC CORNER Q&A 

BIOCHAR: THE FUTURE OF 

GREEN ROOF SUBSTRATES? 

In his latest column exclusively for Greenscape Magazine, 

Dr Tom Young, GRO Board Member and Blue-Green 

Infrastructure Associate at The Environmental Partnership 

(TEP), talks all things biochar with Dr Joerg Werdin, a green 

roof expert who has carried out research into the material that 

is increasingly being used in green substrates... 

For my regular column I have 

decided to carry on interviewing 

academics who are involved 

in interesting green roof research. 

For this article, I spoke to Dr Joerg 

Werdin, a very experienced green 

roof practitioner who has worked in 

Germany, UK and now Australia. Joerg, 

amongst many other things, is an 

expert in the use of biochar on green 

roofs. I spoke to him about his career 

and why biochar is being increasingly 

looked at as a key component of green 

roof substrates... 

Tom Young (TY): Can you give us 

some background on your career to 

date? 

Joerg Werdin (JW): By heart, I’m a 

landscape gardener, and I think that 

will remain true ‘til the end of my days. 

However, rushing out to a worksite 

on a cold and dark winter morning 

in rural Germany made me seriously 

question my choices in my early 20s! 

It was during this time as a gardening 

apprentice when I helped build my first 

green roof; nothing fancy – a humble 

deck with some garden beds in the 

middle of a medieval town. The views 

from up there were stunning and gave a 

completely new perspective to the place 

I thought I knew well. The roof garden 

combined the best of both worlds: a 

quiet retreat just a staircase away 

from the hustle and bustle of 

the town. To me, it was quite a 

revelation that both aspects 

are not mutually exclusive. 

After studying landscape 

architecture, my ongoing 

fascination with green roofs led me to 

take on a position at ZinCo, a global 

green roof market leader based in 

South-West Germany. During that time, 

I got involved with R&D of green roof 

and living wall systems and, lucky me, 

the company sent me to the University 

of Sheffield to work with some of the 

finest green roof experts on a research 

program. This is where I met and 

worked alongside Prof. Virginia Stovin 

who I humbly hold responsible for 

igniting a scientific research spark in 

me. 

Life then blew me across the globe to 

Melbourne, home of my lovely wife 

and a centre for green roof research 

in Australia. I started working as a 

Research Assistant with University 

of Melbourne’s Green Infrastructure 

Research Group, which merged into 

pursuing my own PhD with Prof. Claire 

Figure 1: The Yarra Ranges Biochar Facility 

produces up to 1000m 3 of biochar per year. 

Source: EarthSystems 2023. 

Above: Dr Joerg Werdin after a 

day of sieving biochar! Source 

Carola Pritzkow. 

Left: Dr Tom Young. 

Farrell. While green roofs are nowadays 

business as usual in many northernhemisphere 

countries with temperate 

climates, Australia remains slow in 

uptake. This was the premise of my 

research; How can we adopt green roof 

systems to the hot and dry summer 

conditions in faraway Australia? A 

key was designing the right substrate: 

capable of retaining enough water 

for plants to sustain summer, yet 

lightweight enough to be supported by 

roof structures, and made from locally 

available materials. Biochar ticked those 

boxes, hence I focussed my research on 

using biochar as a green roof substrate 

amendment to develop lightweight 

substrates with high water retention. 

I now work in local government here 

in Melbourne and am fortunate to 

work for Yarra Ranges Council, where 

we recently opened a biochar plant 

producing up to 1000m 3 per year 

(Figure 1, left). 

TY: What is biochar? 

JW: Simply put, biochar is charcoal 

intended as a soil amendment. However, 

that is where the simplicity stops. 

Biochar can be made from any organic 

Continued on page 12 >>> 


EXPERT DESIGN, 

ACCREDITED INSTALLATION, 

& TAILORED MAINTENANCE 

for Optimal Energy Generation! 

ICBPROJECTS.CO.UK

ACADEMIC CORNER Q&A 

>>> Continued from page 10 

material by heating it in a no-oxygen 

environment. The process is known 

as pyrolysis and one of the oldest 

human technologies. The benefits of 

biochar for soil health and fertility have 

been studied scientifically since Wim 

Sombroek’s work on “terra preta” soils 

in the Amazon region. There, ancient 

civilisations had added charcoal and 

food scraps to acidic soils with lowfertility, 

and still today these soils have 

greater fertility and produce greater 

yields than surrounding, unamended 

soils (Lehmann, 2006). 

However, creating purpose-fit biochar 

is much more complicated than first 

meets the eye. While all organics 

are carbon based, their physical and 

chemical structure is highly variable. 

For instance, agricultural or forestry 

residues produce different biochar 

when compared to biochar made from 

sewage sludge. Pyrolysis conditions 

such as temperature and residence 

time affect biochar properties, as well 

as different post-pyrolysis treatments 

such as chipping, sieving, washing or 

inoculating with nutrients. To further 

add to the variability, biochar effects are 

dependent on the soil type the biochar 

is added to (parent soil). For instance, 

addition of identical biochar may 

increase infiltration capacity and reduce 

water retention in clay, but have reverse 

effects in sand. 

While this variability is daunting to say 

the least, it also holds the prospect to 

target-engineer biochar for specific 

applications. This approach was 

popularised by Novak et al. (2009) who 

proposed the concept of “Designer 

Biochar”, aiming to address specific 

soil deficiencies with target engineered 

biochar. This approach seemed 

promising to me, as the desirable 

properties for green roof substrates are 

well known. 

TY: Why is it of interest to green 

roofs – what are its benefits? 

JW: Green roof substrates need to: 

• hold enough water and nutrients for 

plant survival 

• absorb water quickly during rainfall to 

delay and retain stormwater run-off 

• provide drainage to avoid waterlogging 

• be lightweight to not exceed a 

building’s weight-loading capacity 

• ideally be made from sustainable and 

locally available components 

• be free of toxins to avoid polluted run-off 

Biochar has been shown to support 

these requirements when mixed into 

substrates (Beck et al., 2011; Cao et 

al., 2014). However, a mechanistic 

understanding of how to optimise 

biochar for green roof substrate 

amendment was lacking and became 

the starting point of my research. The 

questions to guide my research through 

consecutive experiments were: 

1. What locally abundant raw material 

(feedstock) produces biochar best 

suited for green roofs? 

2. How do biochar properties affect 

green roof substrates in terms of water 

retention, infiltration capacity and 

weight? 

3. How does a biochar amended 

substrate perform under South-Eastern 

Australian summer conditions in 

comparison to an industry-standard 

green roof substrate? 

TY: What did you find out in your 

research? 

JW: I can confidently say that the right 

type of biochar can replace proportions 

of commonly used substrate 

components (e.g., scoria, also called 

Lava or Tuff) without impeding on 

green roof function. However, the devil 

is in the detail, so let’s get to it! 

An abundant feedstock in Australia 

is Eucalypt wood and with increasing 

efforts to decarbonise our economies, 

there’s likely an increasing demand for 

wood as a building material to replace 

carbon intensive concrete. To produce 

sufficient wood supply, plantation 

forestry is a key industry that will 

in turn produce a reliable source of 

woody residue of consistent quality for 

biochar production, hence I focussed on 

Eucalypt biochar for my research. 

In my first experiment, I tested biochar 

made from 18 different Eucalypt 

species on a gradient of wood density. 

Wood density is a measure of solid 

cell wall material per volume of 

wood (Phillips, 1941), thus a proxy for 

wood cell structure which is retained 

during conversion to biochar (Gray 

et al., 2014). The experiment showed 

that lower density wood with thinner 

cell walls and larger cell diameters 

produces lighter biochar with greater 

pore volume for water storage when 

compared to biochar made from higher 

density wood. Thankfully, tree species 

used in Australian plantation forestry 

are generally lower density and fast 

growing, thus abundant feedstock 

material for lightweight and high-water 

retaining biochar should be readily 

available. 

The following experiment explored the 

effects of biochar properties on green 

roof substrate weight, water retention 

and infiltration capacity, hence I 

increased the complexity from looking 

at pure biochar in the first experiment 

to throwing a parent substrate in the 

mix. I added different amounts of 

biochar (10 – 40% by volume) with 

different particles sizes (fine – coarse) 

and made from contrasting woody 

feedstock (low-density E. nitens and 

high-density E. microcarpa) to a scoriabased 

green roof substrate. Differences 

between the feedstock wood species 

had little effect on substrate properties 

and were outweighed by differences 

in particle size and the amount of 

biochar added. In general, increasing 

proportions of fine biochar increased 

substrate water retention but drastically 


educed infiltration capacity which 

would result in water logging on a 

roof. However, increasing amounts 

of coarse biochar also increased 

substrate water retention and 

maintained high infiltration capacity 

for sufficient drainage. In terms 

of substrate weight, all biochar 

treatments (regardless of feedstock 

type and particle size) reduced 

substrate weight by approximately 

15%. Therefore, coarse grained 

biochar seems a preferable and 

less risky choice for green roof 

substrates. 

In my final experiment, I compared a 

biochar amended substrate with an 

unamended control substrate in a full 

green roof system including plants 

under an artificial rainfall regime during 

Australian summer (Figure 2, above). 

While both previous experiments 

were carried out in a lab, this last 

experiment was closest to realistic 

conditions. Surprisingly, treatments 

with biochar retained almost identical 

amounts of rainfall when compared to 

the unamended control over the three 

months of the experiment. While the 

treatments with biochar were lighter 

than the unamended treatments, 

they also showed slightly reduced 

plant growth. This is likely due to the 

high biochar amendment rate of 30% 

by volume, too much I would say in 

hindsight. I must admit that the lower 

than expected rainfall retention and 

evapotranspiration rates in the biochar 

treatments surprised me, and I dug a bit 

deeper. It turned out that the internal 

porosity of the biochar particles is not 

easily filled with water, thus water can’t 

enter fast enough during rainfall. This 

is likely due to the clogging of outside 

pores with fine material from the 

substrate or the biochar itself during 

mixing. Simple processing adjustments 

such as washing the biochar before 

mixing with a parent substrate and 

avoiding fine fractions may improve this 

behaviour, particularly important during 

Figure 2: Green roof experiment. Source Joerg Werdin 

green roof establishment when plants 

are most vulnerable. However, the nearidentical 

hydrological performance 

of both substrate types indicates that 

biochar can still replace proportions 

of conventionally used substrate 

components with better sustainability 

outcomes. 

TY: What further work is needed in 

this area? 

JW: Making the internal porosity of 

coarse biochar easier available for 

water uptake. The clogging of surface 

pores hinders water entry into the 

internal porosity of biochar particles. 

This may be avoided by washing the 

biochar after sieving and grading, and 

by using no-fines parent substrates. This 

could in turn increase substrate water 

retention and thus improve hydrological 

function of green roofs. 

Investigate the long-term performance 

of biochar amended substrates. It is 

known from the literature that biochar 

properties change over time (Joseph 

et al., 2021). Long-term experiments 

investigating the hydrological 

performance of biochar amended 

green roof substrates would be highly 

valuable. 

Carbon sequestration potential 

and biochar price. Converting 

plant-based biomass into biochar 

is a viable mechanism for drawing 

down atmospheric carbon (via 

photosynthesis) and stabilising it 

long-term as biochar in soils and 

substrates (IPCC, 2019). There 

are limited carbon draw-down 

mechanisms available and, in 

comparison to other direct carbon 

capture approaches, pyrolysis is a 

cheap and proven-tested way. The 

further development of carbon 

trading schemes may improve the 

economics of biochar and make it 

more viable in green infrastructure 

applications, not only green roofs, 

and thus overcome the currently 

prohibitive price of biochar. 

Water quality outcomes for green 

roofs. While I focussed my research 

on the hydrological impacts of biochar 

in green roof substrates, biochar’s 

high nutrient retention capacity is 

certainly a big drawcard for using it in 

green roofs. Research (e.g., Beck et al., 

2011; Kuoppamäki et al., 2016) shows 

promising results to limit nutrient 

and pollutant run-off from green roof 

substrates amended with biochar. In 

Australia and other countries with 

separate sewer systems, run-off from 

green roofs enters receiving water 

bodies untreated, hence control agents 

like biochar may ensure green roofs 

don’t contribute to polluting waterways 

Thank you Tom and the readers of 

Greenscape for your interest in my 

research. If you would like to read all 

the gory detail, have a look at my thesis 

for free at: https://rest.neptune-prod. 

its.unimelb.edu.au/server/api/core/ 

bitstreams/88e780cc-1b39-42cfa09c-1c8b82224865/content 

Contact 

Dr Tom Young 

Tel: 0207 5899 400 

Email: tomyoung@tep.uk.com 

Tweet: @DrGreenRoof 


ADVERTORIAL BIOSOLAR ROOFS 

BIOSOLAR FROM OPTIGRUN – 

SOLAR SUPPORT SYSTEMS FOR 

GREEN ROOFS 

Green roofs increase the 

economic and ecological 

functionality of the building. 

Especially in terms of stormwater 

management, buildings with green 

roofs have become an important part 

of the construction world as they 

minimise the environmental impact of 

the building on the environment. 

Benefits of biosolar roofs 

There are many advantages to the 

combination of green roofs and 

photovoltaics, often referred to as 

biosolar roofs. The evaporative cooling 

effect of the vegetation leads to 

an increase in the efficiency of the 

photovoltaic system. At the same time, 

the green roof makes an important 

contribution to preserving the 

natural water balance and increasing 

biodiversity. The varying amounts 

of sunlight and water in front of, 

underneath and between the modules, 

provides a varied habitat for different 

plant and animal species. 

With the pursuit of carbon neutrality 

and changes in building legislation 

photovoltaic (PV) systems are now used 

extensively to achieve energy efficiency 

targets, particularly in the new build 

sector. Multifunctionality is the new goal 

of urban planning, and the combination 

of a green roof and PV system forms a 

particularly efficient proposition in this 

respect. 

The positive effect on biodiversity, 

the increase in the efficiency of the 

PV system evaporative cooling, and 

the possible structural and practical 

advantages of a support system secured 

with a superimposed load require a 

multi-functional and flexible solution. 

Choosing the right solution 

Leading specialist green roof and blue 

roof suppliers Optigrun have over 

50 years’ experience in developing 

new and innovative solutions. The 

challenge when engineering their PV 

array support was to create a product 

that could be entirely ballasted in 

position by the superimposed loading 

of the surrounding green roof build-up 

without a requirement for fixing to the 

roof structure in any way. There was 

also a need for the system to be able to 

support vegetation underneath the PV 

panels, thereby maximising the green 

roof area available. 

With the increased use of blue roofs 

on construction projects to enhance 

stormwater management, Optigrun 

were also keen to develop an additional 

product within their PV support range 


that could be used as an integral part 

of a blue roof specification where a 

photovoltaic array was also required. 

The Optigrun Solar FKD and Solar 

WRB ranges are both load-supported 

solar mounting frames for penetrationfree 

roof mounting of PV modules in 

combination with an extensive green 

roof system. 

The versatile subframe assembly makes 

it possible to mount almost all standard 

solar modules, with inclines of 10°, 

15° or 20°. The rows of modules can 

be installed in a south-facing or eastwest 

orientation. The modules can be 

attached to it both vertically (portrait) 

and horizontally (landscape). 

The Optigrun Solar FKD solution 

is suitable for use as part of an 

extensive sedum or wildflower planted 

specification. The modified base 

drainage and reservoir board which is 

supplied with each support is based on 

the standard Optigrun FKD 25 drainage 

and storage board, and offers both a 

spacious water reservoir and reliable 

drainage of excess water. Combined 

with the Filter Fleece FIL 150, optimum 

water distribution is guaranteed so that 

the vegetation is properly irrigated, 

even under the rows of PV modules. 

The Optigrun Solar WRB solution can 

be used, alongside the Retention Roof 

Flow Control system as part of a softlandscaped 

blue roof specification, 

providing rainwater attenuation and 

discharge delay, as well as water 

storage for vegetation via a capillary 

system. 

The use of the proven Water Retention 

Box WRB 80F helps to maintain the 

natural water balance by increasing 

evaporation and controlling the rate of 

surface water discharge from the roof. 

The design of the new system means 

that there are a minimal number of 

interruptions within the storage void 

thereby maximising capacity. 

Both products, which are designed 

Illustration shows a 

biosolar roof build-up 

with support system. 

Above and opposite: Optigrun offers the 

Solar FKD and Solar WRB support systems. 

and tested in accordance with the 

requirements of BS EN 1991 and 

BS EN 1999 come with a base section, 

drainage and reservoir board, 

aluminium support frame, as well as 

secondary mounting rails and fixings, 

leaving the PV panel supplier to provide 

the chosen modules, inverters and 

associated cabling. The Optigrun Solar 

FKD or Solar WRB support system 

would be installed at the same time 

as the green or blue roof with the 

fixing of the PV panels normally being 

carried out prior to the planting of the 

vegetation. 

Technical and specification support 

Optigrun provide full technical support 

for this product range. This includes 

the preparation of PV module and 

support layouts, wind loading reports, 

together with general specification 

advice. Minimum loadings are provided 

to ensure that the dry weight of the 

vegetation build-up is sufficient to 

maintain the supports in position on all 

areas of the roof. With the Solar WRB 

solution, Optigrun can also provide 

water storage and outflow calculations 

to suit the requirements of the local 

water authority or drainage engineer 

for the project. 

Contact Optigrun 

Tel: 0203 5899 401 

www.optigruen.com 

Email: 

enquiries@optigreen.co.uk 


BUILT ENVIRONMENT 

BIOPLHILIC DESIGN AND 

GREEN ROOFS 

Bethany Smith, Marketing Manager at Hambleside Danelaw, 

takes a closer look at biophilic design – the process of linking 

urban spaces with nature, and an area GRO will be focusing on 

at this year’s Futurebuild exhibition… 

Biophilic design has been utilised 

in architecture for many years: 

the Eiffel tower draws inspiration 

from the femur bone, the stadium built 

for the Munich Olympics uses joinery 

elements that mimic spiderwebs, 

numerous structural marvels aim to link 

urban spaces with nature. Erich Fromm, 

a psychologist first clearly defined 

the idea of biophilia in 1964, asserting 

that there is an inherent link between 

humanity and ecology as a whole. It is 

only natural then, that our buildings 

seek to reforge this connection. 

Green roofs provide a clear way of 

creating a link to nature in a way that 

is clearly beneficial both for occupier’s 

wellbeing and the environment itself. 

Installing plant life such as sedum and 

wildflowers on the roofspace has been 

shown to provide a number of positive 

impacts. For example, by reducing the 

need for artificial cooling, nature is 

supporting our efforts to reach net 

zero carbon emissions while improving 

our thermal comfort and health. By 

decreasing water run-off during heavy 

rainfall, green roofs work alongside 

flood defences to protect our homes 

and businesses. As such, biophilic 

design highlights the need to look at 

environmental, social and economic 

issues together, to make best use of our 

resources. 

GRO (Green Roof Organisation) was 

established to represent UK roofing 

companies which provide green, blue, 

Above: Green roof installation, image courtesy of Hambleside Danelaw. 

and biosolar infrastructure on roofs. 

With a passion for sustainability and 

accessibility, 2023 saw a number of 

new members join the organisation, 

an exhibition at a major trade show, 

changes to the board, the launch of a 

children’s book, the creation of a green 

roof education fund, all while GRO 

influenced key updates to roofing fire 

regulations and established a technical 

group for biodiversity net gain. 

A busy year indeed! 

This year, one of GRO’s goals is to 

continue to raise awareness of green 

roof and blue roof technology in the 

UK and beyond, supporting the green 

roof industry with advice and guidance. 

GRO offers member organisations 

marketing and technical support, such 

as promoting organisations through 

social channels, featured case studies, 

and advice and support on green roof 

projects. 

To learn more about GRO and the 

benefits of green roofing, come and see 

us on the GRO Pavilion at Futurebuild 

2024 (stand B60), where we will be 

discussing biophilic design in more 

detail, or get in touch at: 

admin@greenrooforganisation.org 


Proud to be 

a member of 

the GRO Code 

The sky’s the limit 

With a Green Roof System from Green-tech 

1 

2 

3 

4 

5 

1. Choice of soft and hard landscaping 

materials available, including: 

• Sedum Matting 

• gtSedum Cassettes 

• John Chambers Wildflower Matting 

• John Chambers Green Roof 

Wildflower Mix 

• Turf 

• Planters 

2. Intensive or Extensive Green-tree 

Roof Garden Substrate 

3. Drainage Board System, including: 

• Filter Membrane 

• Drainage Layer 

• Rootbarrier 

4. Waterproofing Layer 

5. Roof Structure 

This diagram of a typical green roof construction is for illustrative purposes only to demonstrate the range 

and types of products available for a green roof installation. 

Green-tech is a leading supplier 

of landscaping and green roof 

materials. Our products have been 

used in many high profile and 

award-winning green roof projects 

throughout the UK. 

We can provide everything you 

need for a successful installation, 

including technical advice, project 

specifications, CAD drawings and 

of course, a full range of Green 

Roof products. 

For more information, book a 

free Green Roof System CPD 

presentation, to be delivered 

online or in your office. 

T: 01423 332100 

www.green-tech.co.uk 

sales@green-tech.co.uk 

@greentechltd 

@greentechuk 

green-tech-ltd

FUTUREBUILD 2024 

GRO PAVILION RETURNS TO 

FUTUREBUILD! 

The GRO Pavilion was one of the top 5 most visited locations at last 

year’s Futurebuild, but the association isn’t resting on its laurels for 

this year’s exhibition! Below, the GRO team highlight what they’ll 

be showcasing at this year’s Futurebuild, with key green roof sector 

trends and issues set to be debated in a busy seminar programme, 

and visitors able to tap into the knowledge and source advice from 

GRO’s experts and member company teams in the GRO Pavilion... 

Following the success of the 

first ever GRO Pavilion at last 

year’s Futurebuild, we are 

looking forward to welcoming even 

more members to ExCeL London for 

this year’s exhibition in March 2024. 

As one of the top 5 most visited 

locations last year, we are looking 

forward to welcoming even more built 

environment professionals interested in 

providing reliable, great quality green 

infrastructure. 

Our programme of talks and debates 

taking place on the Sustainable 

Infrastructure stage will look at many of 

the important issues facing the green 

roof industry. Visitors are able to listen in 

and get involved with the discussion, with 

experts providing talks over the three days: 

• Tuesday 5th March 14:15-15:00: 

Demonstrating compliance with Green, 

Blue and BioSolar roofing systems. 

Chaired by Mark Harris, supported by 

Giles Doland, Georgia Gilbert and Tom 

Young. 

• Wednesday 6th March 10:30 – 11:15: 

Competency within Green, Blue and 

BioSolar Roof Design and Installation. 

Chaired by Chris Bridgman, supported 

by David Fisher, Jenny Bailey and Dan 

Dean. 

• Thursday 7th March 15:00 – 15:45: 

How can Biophilic Design contribute to 

wellbeing and mental health in Cities? 

Workshop led by Matthew Hoddinott. 

Above: The GRO Pavilion was busy throughout Futurebuild 2023, with visitors keen to learn 

more about green roofs and associated systems, plus gain expert advice for their projects. 

Above: Tom Young of GRO and TEP delivers 

a seminar at Futurebuild 2023. 

Visitors can also chat to the GRO team 

in the café, and find out more about 

how to order our first ever children’s 

book – Journey to the Green Roof, 

produced by Tales from Mother Earth. 

GRO will be represented on our stand 

B60-64, alongside our exhibiting member 

companies from throughout the green 

roof supply chain in the Pavilion (stands 

B62- C66). Find out more about what 

they have to offer below: 

GeoShield Warranty Support: 

Third party integrity testing for the 

waterproofing components of Blue, 

Brown & Green Roofs. Independent of 

the roofing contract, as requested by 


the LABC, Premier Guarantee, NHBC 

and many other UK Warranty providers. 

The Warranty Support function is 

intended to minimise the risk of 

specified defects and damage to the 

building, enabling the comprehensive 

cover of a Latent Defects Warranty. 

Formed in 2015 by experts who have 

decades worth of experience in the field 

of complete building envelope on-site 

quality assurance programming, both at 

home & internationally. 

• Founder members of the British 

Verification Council 

• Members of the Roofing & 

Waterproofing Test Association 

• Members of the Green Roof 

Organisation 

• Members of the Confederation of 

Roofing Contractors 

• Members of Constructing Excellence 

• ISO 9001 Accredited 

• ISO 14001 Accredited 

• Construction Line Gold. 

Ravago Building Solutions UK: 

Ravago Building Solutions UK is the UK’s 

trusted source of high-performance 

XPS insulation. Its technical experts 

offer more than 100 years of combined 

insulation experience. 

Ravathem XPS X is at the heart of 

many of the UK’s most recognisable 

and energy-efficient residential and 

commercial buildings with its XPS X 

range of high performance insulation 

products, offering architects and 

building specifiers unparalleled 

flexibility and the ability to meet the 

most demanding design specification. 

Visit Stand B62 and meet the Ravago 

commercial team to learn more about 

the high-performing Ravatherm XPS X. 

Sika: 

Sika Limited and Sika Ireland Limited 

are part of the global Sika Group, 

specialising in the manufacture and 

supply of chemical-based products. 

Sika has a global leading position in the 

development and production of systems 

and products and has subsidiaries in 

103 countries, manufactures in over 

400 factories, and develops innovative 

technologies for customers around 

the world that facilitate the sustainable 

transformation of the construction and 

transportation industries. With more 

than 33,000 employees, the company 

generated annual sales of CHF 10.5 

billion (£9.4 bn) in 2022. 

In the UK and Ireland, Sika provides 

market-leading solutions for building 

finishing, concrete, waterproofing, 

roofing, flooring, refurbishment, sealing 

& bonding, and industry, and has 

manufacturing sites in Welwyn Garden 

City, Preston, Leeds, Wishaw, Redditch, 

and Dublin, with more than 900 

employees and a turnover of more than 

£300 million. 

Futurebuild takes place at 

ExCeL London from 

05-07 March 2024 

www.futurebuild.co.uk 

Head to the GRO Pavilion 

at stand B60 

Wallbarn: 

Wallbarn brings the award winning M-Tray 

modular green roof to Futurebuild 2024 

– find us in the GRO Pavilion. M-Tray is 

a pre-grown, fully established green 

roof system with mature sedum or 

sedum / wildflower plants pre-loaded 

into easy to carry cassettes. Just click 

the cassettes together and an instant, 

seamless green roof is installed. 

M-Tray is the only modular green roof 

system in the UK that has been physically 

fire tested, meaning we can prove that 

there is zero penetration from fire. 

If the roof deck beneath ever needs 

inspection, just lift the modules 

to access the subsurface without 

destroying the plants. As each module 

can be carried by hand, difficult to 

access roof spaces can be reached, 

making M-Tray ideal for retrofit. 

Come see, touch and discuss M-Tray at 

the GRO Pavilion at Futurebuild 2024. 

Wraxalls: 

Wraxalls have 17 years’ experience of 

producing substrates for the living roof 

market. We can offer bespoke grades, 

lightweight mixes, specific blends that are 

tailored to planting schemes, and handle 

all your logistical aspects. Our bagging 

units cater for certified one-tonne bulk 

bags and 25 kg polythene bags, robotically 

palletised onto reinforced pallets. Experts 

in site work and storage, please come and 

discuss your project needs with us. 


GREEN ROOFS FIRE SAFETY 

What’s not to love 

about a green 

roof? Not only 

do they transform unused 

and often unattractive 

flat roof areas into longlasting, 

beautiful, spaces 

delivering important 

ecological and environmental 

benefits, they 

provide physiological and 

social benefits as well 

as supporting increased 

productivity and creativity. 

There’s also increasing 

importance being given 

to their ability to manage 

stormwater run-off, a 

particularly attractive 

feature with increasingly 

frequent flooding in the UK. 

A major advantage of green roofs has 

always been their ability to absorb 

water and slow the flow of heavy rainfall 

into drainage systems. As more land is 

lost to house-building, and homeowners 

leverage permitted development 

rights to extend properties, permeable 

surfaces are being lost at an alarming 

rate. Increasing the number of green 

roofs goes some way to redressing the 

balance. 

With such a wide range of benefits 

– including potential to feed into 

Biodiversity Net Gain (BNG) and 

Environmental, Social and Governance 

(ESG) targets, plus Sustainable 

Development Goals (SDGs) – green 

roofs have the ability to deliver for 

clients with a wide range of differing 

needs. 

ENSURING SAFE GREEN 

ROOFS ARE THE NORM 

Whilst Julian Thurbin, Director at Wallbarn, believes green 

roofs should be the norm for domestic and commercial 

properties with suitable flat roof space, he says fire 

performance is one area that needs wider consideration... 

Above: 1,500m 2 of Wallbarn’s M-Tray modular green roof system was installed 

alongside a solar PV system at Turing House School in South West London. 

The norm not exception 

With so many positives, isn’t it about 

time that green roofs became the norm 

for domestic and commercial projects 

with suitable flat roof space? They can 

be quick and easy to install, are longlasting 

(75 years and counting for one 

development in Germany) and require 

minimal maintenance, giving them an 

attractive whole-life cost. Not only will 

a living roof help address the Urban 

Heat Island effect, improve air quality 

and support wildlife/pollinators, it can 

also provide a positive visual impact 

and valuable outdoor recreational areas 

where appropriate. 

Clever clients and specifiers are going 

one step further, pairing green roofs 

with solar panels to deliver an even 

stronger environmental story. Wallbarn 

was involved in a project of this nature 

at Turing House School in South West 

London, installing 1,500m 2 

of its M-Tray modular 

green roof system 

alongside a solar PV 

system, to deliver a roof 

that not only looks great 

but also works hard for 

the school. 

Fire performance 

The specification process 

for green roofs is relatively 

straightforward, especially 

for modular solutions such 

as M-Tray which is supplied 

with all elements of an 

established green roof 

contained within 500cm 

x 500cm pre-assembled, 

easy-to-transport trays. 

But there is one key area that we 

feel needs wider consideration – fire 

performance. 

Well-designed, correctly installed and 

maintained green roofs can resist the 

spread of flame. To assist designers 

in achieving this, the government 

has published two key documents 

– Approved Document B (ADB) and 

DCLG document ‘Fire Performance of 

Green Roofs and Walls’. Good practice 

supports these being considered 

together with the Green Roof 

Organisation’s GRO Code. 

ADB is the main authority, detailing the 

minimum legal requirements and inpractice 

guidance. It states that a roof 

system must achieve a classification 

rating of B ROOF t(4). This is achieved 

either by an assumption of compliance 

where the substrate thickness exceeds 



Visit us on Stand C52 

ZinCo SolarVert system for biosolar roofs 

to achieve increased biodiversity and 

green energy on one roof space 

Your Green Roof System Supplier 

• The UK‘s most comprehensive product range for podium decks and green roofs 

• Tested system build-ups with ETA certification (European Technical Assessment) 

• Landmark projects all over the globe 

• Technical support you can rely on 

• 40 years of expertise 

• Nationwide, fast deliveries 

• UK stock 

ZinCo Green Roof Systems Ltd. . office@zinco-greenroof.co.uk . T: 01993 229700 . www.zinco-greenroof.co.uk

GREEN ROOFS FIRE SAFETY 


80mm build up, or where there has 

been a physical fire test to CEN/TS 

1187:2012 Test 4 Test Methods For 

External Fire Exposure to Roofs. The 

test must be carried out under BS 

EN 13501-5:2016 Fire classification of 

construction products and building 

elements. In practice this means 

physical fire tests of the whole roof 

system ‘as installed’ to demonstrate B 

ROOF t(4) is achieved. 

ADB states that a test report to BS EN 

13501-5:2016 for the exact construction 

is key. So if the insulation thickness is 

changed, membrane switched or depth/ 

elements of the substrate altered, 

the fire certificate may be invalid. 

This would mean compliance with B 

ROOF t(4) requiring many different 

physical fire tests to take into account 

the different scenarios of a green roof 

build-up. However, ADB offers a solution 

via EXAP reports. 

EXAP reports 

These state that the test results for 

the product (tested in accordance with 

CEN/TS 1187:2012 test method 4) have 

an extended application (EXAP) to be 

used in a larger range of applications. 

This extended application is carried out 

in conformity to CEN/TS 16459:2019 

and the application document contains 

extrapolation rules relevant to the 

test method and performance of 

the product. In short, it enables the 

physical test data to be used in more 

applications. 

Designers should look for green roof 

systems that have passed physical fire 

tests of one hour, achieve B ROOF t(4) 

and hold the EXAP Report, meaning 

their fire classification allows them 

M-Tray installed on a 

domestic roof. 

to be used as part of a green roof 

system with a variety of fire compliant 

membrane/insulation build-ups so long 

as those products also have B Roof 

t(4) EXAP. ADB goes on to say that 

if the green roof build-up from the 

deck to the finished surface includes a 

minimum 80mm of substrate with less 

than 50% organic content, then it can 

be assumed there will be no spread of 

fire. 

However, this does mean that growing 

medium rules need adhering too. It 

needs to comply with British Standard 

BS 8616:2019 in terms of composition 

certainly. If installers lay substrate 

thinner than 80mm in a roll-out system 

it will not comply. Modular systems, 

such as M-Tray, have been physically fire 

tested and achieve B ROOF t(4) with an 

EXAP Report conforming with CEN/TS 

16459:2019. 

Wallbarn has produced a white 

paper outlining fire performance 

considerations when specifying green 

roofs, view it at www.wallbarn.com 

Contact 

Wallbarn 

M-Tray passing its 

physical fire test. 

www.wallbarn.com 

Tel: 020 8916 2222 


Wallbarn’s award winning M-Tray ® modular green roof 

completes Turing House School in Twickenham. 

M-Tray ® is physically fire tested to BROOF (t4), delivering 

peace of mind and a beautiful living roof. 

Tel: 0204 527 4220 

www.wallbarn.com 

| BRITISH GROWN | QUICK DELIVERY | EASY INSTALLATION | ALL-YEAR VEGETATION |

GREEN & BLUE ROOFS 

In today’s fast expanding 

market, green and blue roofs 

are being increasingly seen 

as complex ecosystems, and 

their success hinges upon a 

robust, invisible foundation – the 

waterproofing system. This is a 

key part of the design process 

and is where we deliver this 

foundation with meticulous 

precision. But there is a 

whole lot more behind 

every project. 

Our expertise in 

advanced membranes, 

drainage strategies 

and root-resistant 

technologies ensures the 

structural integrity of every 

building remains uncompromised. We 

meticulously assess load capacities, 

factor in anticipated rainwater and 

storm patterns, and tailor drainage 

solutions to address both immediate 

downpours and long-term water 

management. 

Building a high-performance green 

or blue roof requires a coordinated, 

multi-disciplinary approach. At Proteus 

Waterproofing, we collaborate with 

architects, contractors and other 

industry professionals to ensure that 

every aspect of best practice is adhered 

to at each stage of the project. 

This means considering factors such 

as wind load, roof pitch where relevant, 

GETTING PROJECTS RIGHT 

FOR FUTURE GENERATIONS 

The rooftop is no longer a blank space. As Justin Pitman, Sales 

Director at Proteus Waterproofing, explains, for architects it’s 

a canvas for innovative engineering and quality waterproofing 

solutions, one where sustainability is key, particularly for 

green and blue roofs. In this article, Justin points out this is 

why Proteus Waterproofing works closely with specifiers from 

design to final delivery to deliver the best possible practice – 

and states ‘between us we are helping to reshape the urban 

landscape…’ 

Left: Justin Pitman, Proteus Waterproofing. 

Above: Proteus Waterproofing was involved with 

the green roof project at Cygnet Hospital. 

vegetation selection and irrigation 

requirements. Our bespoke design 

solutions ensure optimal performance, 

maximising the environmental benefits 

while ensuring the long-term health of 

the rooftop ecosystem. 

Our commitment extends beyond 

the initial installation. We offer 

a comprehensive maintenance 

programme, ensuring every green 

or blue roof continues to thrive over 

time. From customised fertilisation 

schedules where needed, to vegetation 

monitoring and drainage system 

upkeep, we strive to be the long-term 

partner in helping to maintain each 

roof. 

In many ways, building a thriving green 

or blue roof is akin to nurturing a living 

organism. Every layer, from the 

robust waterproofing membrane 

to the carefully chosen plant 

palette, plays a crucial role in 

its health and function, which is 

why the need to adhere to best 

practice is so important. 

Good drainage, for example, is key 

to a successful project. Stagnant 

water is the enemy of both the 

roof and the rooftop ecosystem, 

which is why we prioritise efficient 

drainage systems, be it through 

geotextile layers, carefully sloped 

roofscapes or integrated drainage 

boards. This ensures healthy root 

growth and prevents damage to 

the underlying structure. 

We are also aware that green and 

blue roofs add significant weight to a 

building. We work closely with architects 

to optimise structural support, often 

utilising lightweight growing media and 

plant selections to minimise the overall 

burden. 

It’s more than just a roof –- biodiversity 

matters. A diverse plant palette not only 

fosters a more aesthetically pleasing 

landscape, but also attracts pollinators, 

creating a mini-ecosystem buzzing 

with life. This is why we encourage 

incorporating native plant species and 

varying heights to promote ecological 

balance. 

Paradoxically, sustainability starts 


from the ground up. This means 

we make every effort to prioritise 

sustainable materials in every layer of 

our green or blue roof designs. We opt, 

where possible, to use waterproofing 

membranes that contain recycled 

materials such as our own Proteus Cold 

Melt and innovative systems such as 

Proteus Pro-Living. 

Pro-Living isn’t just a green roof, it is, 

as the name suggests, a living canvas. 

The system acts as lungs for our cities, 

filtering pollutants and particulates, 

leading to improved air quality and 

public health. When used in conjunction 

with blue roofs, the system acts as a 

sponge for urban downpours, mitigating 

storm water runoff and reducing 

pressure on overburdened drainage 

systems. 

Working in conjunction with Pro-Living 

is Cold Melt. This groundbreaking 

membrane, crafted with recycled 

rubber crumb and organically grown 

products, ensures superior and proven 

waterproofing performance for green 

and blue roofs. The system seamlessly 

bonds to a variety of substrates, 

including concrete, asphalt and even 

timber, making it ideal for diverse roof 

designs. 

Together, Pro-Living and Cold Melt 

form a powerful duo, engineering highperformance 

green and blue roofs 

that go beyond aesthetics. They offer 

environmental responsibility, ecological 

benefits, efficient space utilisation and 

energy savings. 

While green roofs are given much of 

the attention, blue roofs deserve equal 

consideration – and of course it is not 

uncommon to have a combination 

of the two. These water-storing roofs 

act as miniature reservoirs, mitigating 

storm runoff, reducing pressure on 

urban drainage systems and providing 

valuable irrigation when needed. 

We integrate innovative blue roof 

technologies such as detention tanks, 

retention mats and advanced irrigation 

systems, to maximise water harvesting 

potential. 

We are particularly aware that a green 

or blue roof is not just an architectural 

embellishment – it’s a powerful tool for 

building resilient cities. They insulate 

buildings, reducing energy consumption 

and mitigating the urban heat island 

effect. They filter pollutants, improving 

air quality for city dwellers – and they 

provide much-needed green spaces, 

fostering urban biodiversity and 

offering mental health sanctuaries. 

Demand for both green and blue roofs 

continues to grow as we try to mitigate 

climate change, and according to most 

industry experts, there is no doubt that 

this market sector will boom for many 

years to come. 

It is why we have to get it right for 

future generations – just another 

reason why we at Proteus are proud to 

be helping to lead the way. 

Contact 

Proteus Waterproofing 

www.proteuswaterproofing.co.uk 

Tel: 01268 777 871 

LinkedIn: 

Proteus Waterproofing 


BLUE ROOFS 

A CLOSER LOOK AT DUBLIN’S 

‘FIRST EVER BLUE ROOF’ 

With new planning rules to abide by in Dublin, the developers 

of a commercial three-storey residential apartment building 

had to demonstrate that its scheme would have a blue green 

roof to obtain planning permission. ACO worked together 

with Beton Construction Services to design and specify an 

innovative blue green system that would manage stormwater 

runoff, improve resilience, and be the first of its kind in the city. 

In 2021, Clonvara Developments 

set sights on redeveloping 47-48 

Chelmsford Road in Ranelagh, 

County Dublin, into a residential 

apartment building. However, as part 

of new planning policies introduced by 

Dublin City Council (DCC), the scheme 

would need a blue green roof so it could 

be granted planning approval. 

Under DCC’s Green Blue Roof Policy, 

all new developments with roof areas 

exceeding 100m 2 need a blue green 

roof, which are recognised with helping 

reduce the risk of flooding, helping 

to mitigate climate change, whilst 

providing amenity and biodiversity 

benefits. DCC also identified that these 

multi-purpose roofs would be critical 

in a city like Dublin, where much of the 

land is already built up and space for 

sustainable urban drainage systems 

(SuDS) is limited. 

This is where Beton Construction 

Services (Beton) and ACO Building 

Drainage (ACO) joined forces to create 

the first ever blue green roof in Dublin. 

Beton is a leading subcontractor in 

surface protection services in Ireland 

and was brought in by SCD Consulting 

as a nominated specialist contractor 

on the project to design and install 

the blue green roof. ACO provided 

consultation for the design of the blue 

roof attenuation system including 

hydraulic calculations and rainfall event 

modelling, and supplied its patented 

RoofBloxx system to form the blue roof 

attenuation tank that sits on top of the 

building’s roof. 

Creating a waterproof roof 

A key part of the consultation was 

ACO’s assessment of the hydraulic 

requirements, which was based on 1 in 

100-year time series rainfall, as well as 

accounting for a 40% uplift in climate 

change. Following the assessment, ACO 

specified its RoofBloxx attenuation 

system to cover a catchment area of 

131.8m 2 , installed on an inverted blue 

roof. 

Introducing the ACO solution to 

an inverted roof separated the 

competing drainage requirements. 

By engineering an elevated shallow 

structural attenuation system that 

operates independently of the flat roof 

drainage system, it allowed the roof to 

be engineered to known standards and 

best practice, without compromising 

the ability of the roof to drain quickly in 

extreme circumstances. 

Beton used its MasterSeal 2103 coating 

system as the roof waterproofing 

membrane. This guaranteed the 

concrete roof slab was completely 

sealed and watertight. To insulate 

the roof, it used Ravatherm XPS 300 

SL lining, along with a separation 

membrane. 

As the ACO system doesn’t rely on 

the roof waterproofing to also act as 

an attenuation liner, it greatly reduces 

risk and in the case of an inverted roof 

system, it prevents possible buoyancy 

of insulation and potential reduction in 

the building’s U-values. When rain falls 


Images show the installation of the ACO blue-green roof on the Dublin 

apartment block by Beton Construction Services. 

it is captured in the open top tank and 

discharged slowly via a flow restrictor 

at 0.28 l/s and then into the perimeter 

gravity drainage system. In extreme 

circumstances any excess rainfall can 

bypass the attenuation system through 

internal overflows and at the perimeter 

of tank and into the roof outlets. 

A total of 240 85mm-thick RoofBloxx 

units were used to form the blue 

roof, stacked together in two layers 

and providing 3.77m3 of stormwater 

storage capacity. A 10mm drainage 

layer was used to create the structural 

drainage layer that the lined open top 

attenuation tank sat on. 

Dan O’Connor, Business Development 

Manager at Beton, led the project and 

said: “When we were approached about 

this job, we knew we’d need guidance 

from blue roof specialists. We turned 

to ACO because we know they not 

only have innovative products like the 

RoofBloxx system, but they have the 

knowledge, experience and assisting 

tools to make sure that the job runs 

smoothly. With ACO’s support, the 

project was swiftly granted planning 

approval, and we and the developers 

have peace of mind that the roof is 

protected for years to come.” 

Sean Drudy from SCD Consulting 

commented: “When we were appointed 

for this project on Chelmsford Road, 

we did some quite extensive technical 

and research appraisals of blue roof 

systems available on the market. We 

specified the ACO RoofBloxx system 

for the project in conjunction with 

Beton Construction Services Limited 

as the installation company, as both 

companies and their systems came with 

excellent reputations. 

“We were very happy with the end 

result and found the technical design 

and documentation offered along with 

the installation and performance on site 

to be to a first-class standard.” 

Going green 

Besides storing and slowing the water 

down to prevent flooding, the blue roof 

helps with other functions – cooling 

for the building in summer, providing 

amenity and biodiversity, as well as 

reducing the urban heat island effect. 

Meanwhile, the water held in the 

attenuation tank helps irrigate a green 

roof made from a layer of sedum 

carpet. This roof provides greenery 

on top of the building, attracting 

wildlife and promoting biodiversity in 

the inner-city area. Additionally, the 

plants contribute to reducing CO2 and 

enabling the roof and building to be 

better for the planet. 

Neill Robinson-Welsh, Consultant for 

ACO, said: “We are proud to have 

partnered with Beton on the first 

ever blue roof in Dublin. Managing 

and caring for water will only become 

more important as the issue of water 

resilience grows. It’s fantastic to see that 

Dublin City Council has put planning 

controls in place, and thanks to our 

collaboration with Dan and the team at 

Beton, we have constructed a roof that 

performs multiple functions, ensuring 

that rainwater is not only slowed down 

but also put to good use.” 

Find out more about 

ACO Building Drainage 

and the RoofBloxx 

attenuation system 

www.aco.co.uk/products/ 

roofbloxx 


SOLAR PV 

SPECIFYING COMMERCIAL PV INSTALLATIONS: 

THE KEY CONSIDERATIONS 

The number of commercial and industrial buildings installing photovoltaic systems is growing 

exponentially. With this in mind, Chris Cowling, from Aztec Solar Energy, explains how to get 

the specification and installation right for now and the long term... 

The demand for solar PV is 

particularly strong in public 

sector, commercial and 

industrial buildings, as organisations 

seek to meet their carbon reduction 

commitments, reduce their electrical 

costs and secure their supply. 

Payback periods are typically about 

5-7 years, but depending on electrical 

consumption they can be as short 

as 3 years. After that, you are saving 

or even generating revenue by 

exporting it back to the grid. A good 

PV module will still be producing 

90% of its output even after 25 

years, so the potential lifespan of the 

system could be even longer. 

To plan renewable generation over 

a long period you must specify a 

system that meets the needs of 

your organisation now and in the 

following decades. You must 

plan the practicalities of 

the installation plus the 

future operations and 

maintenance to minimise 

its total lifecycle cost. 

It all starts with the design 

and a clear idea of your electrical 

consumption and what it is likely to 

be in the next few years. Remember, 

this could increase in the future 

if you install ground source or air 

source heat pumps and electric 

vehicle charging. 

You will also need to consider 

the roof structure and its load 

bearing capacity, as well as the best 

areas to install the PV modules. 

This is to maximise their output, 

avoid skylights and other services 

and consider safe passage for 

Left: Chris Cowling, Aztec Solar 

Energy. 

future operations and 

maintenance, and in case 

of an emergency. 

Planning for repair and 

maintenance 

If you outsource the design and 

installation then it’s a good idea 

to employ a company who also 

provide operations and maintenance 

support, as they will have a clear 

understanding of what to consider 

for the long term. 

For product specification you should 

only consider tier 1 products. These 

are audited for performance and 

also for their provenance. The last 

thing you want is to use PV panels 


Solar PV installation at Warwick University 


It’s more 

LEARN MORE 

than a roof 

It’s a Marley Solar Roof System. 

You may just see a roof. But by installing the complete 

Marley Solar Roof System, you’ll see benefits of 

a solution designed to work together, whilst 

making the most of the growing demand 

for roof integrated solar panels. 

It’s more than a roof, it’s an 

opportunity for roofers. 

marley.co.uk

SOLAR PV 


manufactured from a non-reputable 

source. 

PV modules generally have a 

warranty for 25 years and will in 

many cases last even longer, whereas 

inverters could need replacing 

after 10 years. You need to plan for 

future access for the maintenance 

of both, as well as their potential 

replacement. 

And many commercial installations 

will have several thousand PV 

modules, so think about remote 

monitoring of the system so that 

a maintenance team can clearly 

identify and find where a fault is. 

At a basic level, PV panels will 

need cleaning regularly, but if they 

need replacing or maintenance 

then remember that they will be 

generating DC voltage electricity, 

so you need to mitigate this risk to 

personnel. 

Safety first 

PV modules typically have an output 

voltage of 30-60V, so connecting 

several of these modules serially in a 

string creates a high voltage of up to 

1000Vdc in a commercial installation, 

which can be dangerous to 

personnel. Traditional string inverters 

cannot reduce this DC voltage even if 

they are turned off. 

This has two implications; personnel 

will need experience in working on 

live equipment, but more importantly 

you need to select an inverter that 

will reduce the voltage to a safe level 

for maintenance or in an emergency. 

Fortunately, inverter technology 

has caught up with this safety 

requirement. Systems like SolarEdge 

have power optimisers, inverters 

and individual monitoring on each 

module. This allows for the automatic 

shutdown of PV arrays and lowers 

and maintains the voltage in all DC 

conductors below 50V and to 1V per 

optimiser for either maintenance or 

in an emergency. 

A further safety requirement for 

inverters is that they must detect 

and terminate an electrical arc by 

shutting down. Such arcs could be 

due to connectors or cables being 

damaged or not properly connected. 

Installation 

Every installation is different and 

each poses its own challenges. 

Factors to consider include when 

you can get access to the building 

Solar PV installation at Warwick University 

to crane or lift the PV modules 

onto the roof, how long the power 

will be shut off for connection and 

commissioning, and the health and 

safety of the building occupants and 

those installing the system. 

The specification, design, 

commissioning and ongoing 

maintenance of a PV system is vital if 

an organisation is going to maximise 

the rewards from renewable selfgeneration 

over its long lifespan. 

Get the design and specification right 

and you will reap the rewards for 

decades. 

Contact 

Aztec Solar Energy 

www.aztecsolarenergy.co.uk 

T: 0845 467 5058 


Great people are the 

secret to our success. 

We are the UK’s trusted source of high-performance 

XPS insulation. Our technical experts offer more than 

100 years of combined insulation experience. 

Ravago is committed to providing the UK market with high performance insulation 

solutions with world-class technical expertise. 

The Ravatherm XPS X range of high performance insulation products offers 

architects and building specifiers unparalleled flexibility and the ability to meet the 

most demanding design specification. 

www.ravagobuildingsolutions.co.uk 

ravago-building-solutions 

Download our new digital tool: 

Ravathermapp.com 

Technical support: 

technical.uk.rbs@ravago.com 

chris.roughneen@ravago.com 

Roofing sales manager: 

richard.powell@ravago.com 

07967 496011 

Account managers 

(Distribution): 

Adam Hilmi 

(North England & Scotland) 

adam.hilmi@ravago.com 

07436 145034 

Natalie Sutton 

(South England & Midlands) 

natalie.sutton@ravago.com 

07976 530510

Spring 2024

Create successful ePaper yourself

Delete template?

Save as template?