BPIE: Europe's buildings under the microscope - PU Europe
BPIE: Europe's buildings under the microscope - PU Europe
BPIE: Europe's buildings under the microscope - PU Europe
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iii. O<strong>the</strong>r requirements<br />
A number of countries (e.g. Austria, Denmark, France, Estonia and Poland) have introduced minimum<br />
requirements for specific fan power (generally expressed in W/l.s or kW/m 3 .s.). Given <strong>the</strong> increasing<br />
use of mechanical ventilation system, <strong>the</strong> fan power requirement in low energy <strong>buildings</strong> is becoming<br />
an important issue. Additionally most countries have requirements associated with <strong>the</strong> minimum<br />
performance of boilers and airconditioning systems. Most building codes require minimum levels of<br />
daylight to be achieved within <strong>buildings</strong>, whilst ensuring that solar gains do not result in significant<br />
overheating and/or <strong>the</strong> requirement for air conditioning. Building requirements associated with limiting<br />
solar gains vary from simple approaches (e.g. limiting window areas on building aspects exposed to solar<br />
gains) through to requirements for complex modelling and simulation to demonstrate that effective<br />
measures have been adopted to provide solar protection. The Concerted Action report 1 recommended<br />
that much greater attention should be given to <strong>the</strong> issue of estimating <strong>the</strong> impact of summertime<br />
overheating in <strong>the</strong> methodology in order to reduce <strong>the</strong> rapid increase in demand for air conditioning.<br />
In addition to specifying maximum U values, several countries have also set limits for maximum<br />
permissible <strong>the</strong>rmal bridging. This is generally expressed in W/mK. Thermal bridges can significantly<br />
increase <strong>the</strong> building energy demand for heating and cooling and in nearly Zero Energy Buildings<br />
<strong>the</strong>rmal bridging can account for a significant proportion of <strong>the</strong> total heat loss or gain. Thermal bridging<br />
is specific to <strong>the</strong> design and specification and can be complex and time consuming to calculate. For this<br />
reason, some countries allow a default <strong>the</strong>rmal bridging value to be used, based upon a percentage<br />
(typically 15%) of <strong>the</strong> overall heat loss calculation. However, if a detailed <strong>the</strong>rmal bridging calculation has<br />
been <strong>under</strong>taken, which demonstrates that <strong>the</strong>rmal bridges have been reduced or eliminated, this value<br />
can be used instead of <strong>the</strong> default. ASIEPI estimate that “a third of EU Member States have no real ‘goodpractice’<br />
guidance on <strong>the</strong>rmal bridges in <strong>the</strong> framework of <strong>the</strong>ir building energy regulations. The quality<br />
of guidance in <strong>the</strong> remaining States is very varied” 35 .<br />
35<br />
ASIEPI Information Papers P188 and P189 http://www.asiepi.eu/wp-4-<strong>the</strong>rmal-bridges/information-papers.html<br />
<strong>Europe</strong>’s <strong>buildings</strong> <strong>under</strong> <strong>the</strong> <strong>microscope</strong> | 85