BPIE: Europe's buildings under the microscope - PU Europe

In addition to the lack of sufficient thermal insulation, gaps at connection points between
different elements of a building envelope (e.g. window frame and surrounding wall) can lead to
considerable energy wastage. This highlights the importance of appropriate air tightness levels in
a building. A building with high air tightness levels (that is, high air leakage levels and high n 50
values 18 )
typically suffers from high energy consumption levels while a building with very high air tightness levels
can cause unhealthy conditions for its occupants, especially if there is inadequate ventilation. The latter
is typically linked to poor indoor air quality and the so-called sick building syndrome. Establishing the
appropriate level of air tightness in buildings is, therefore, a key aspect from the viewpoints of energy
usage and comfortable occupant conditions. Poor detailing in past construction techniques means that
older buildings encounter high leakage levels.
This is illustrated by Figure 1C8 which shows typical values of air tightness levels (measured at 50 Pa in h -1 ) of
single family houses for a number of countries across Europe. It is evident that in countries with long traditions
in energy regulations (such as Germany and Denmark), the older stock demonstrates far lower air leakage
levels compared to the old stock in Central & Eastern regions (such as Czech Republic, Latvia and Bulgaria).
However, even with today’s levels of air tightness levels, studies have shown that envelope leakage can
increase the heating needs by 5 to 20 kWh/m²/a in a moderate climate (2500 to 3000 degree-days) 19 .
Non-residential buildings
Understanding energy use in the non-residential sector is complex as end-uses such as lighting,
ventilation, heating, cooling, refrigeration, IT equipment and appliances vary greatly from one building
category to another within this sector.
Over the last 20 years in Europe electricity consumption in European non-residential buildings has
increased by a remarkable 74%, as depicted in Figure 1C9. This is compatible with technological advances
over the decades where an increasing penetration of IT equipment, air conditioning systems etc. means
that electricity demand within this sector is on a continuously increasing trajectory.
(c.f. absolute difference in electricity use between 1990-2009).
Mtoe
Figure 1C9 – Historical final energy use in the non-residential sector in the EU27, Norway and
Switzerland
Source: Eurostat database
90
80
70
60
50
40
30
20
10
0
1990
1991
All fuels
1992
1993
1994
1995
Electricity
18
n 50
represents the total air change rate in a building caused by pressure difference of 50 Pa
19
As quoted in the ASIEPI project (www.asiepi.eu)
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Europe’s buildings under the microscope | 51