Z E M C H 2 0 1 2 I n t e r n a t i o n a l C o n f e r e n c e
44
cooling challenges) and
Lighthouse
, all buildings exhibit A/V ratios very close or lower
than 0.7 m
2
/m
3
.
Figure 5: Compactness values of case studies
With respect of strive for reducing seasonal cooling loads, passive approaches are
divided into three functional component sets: overheating prevention, heat rejection, and
control. From the prevention point of view, sunshading, which is critical for passively
heated buildings, is present in all cases under analysis under the form of fixed and
movable overhangs and/or external screens. As for heat rejection, natural (cross)
ventilation is one of the most commonly used strategies used to reduce the internal
loads in passive design. It is sometimes more effective during the night (night cooling)
when outdoor temperatures are lower than indoor temperatures. When coupled to an
earth tube system that uses the earth as the cold source, ventilation may also prove
useful in reducing the building internal loads by pre-cooling ventilation air and evacuation,
rejection. Partly the stack effect is used (by open spaces and windows in different
heights) to increase the passive cooling (e.g.
Lighthouse
). Information on the use of
these strategies in the buildings under analysis is synthetized in figure 6.
Energy Efficiency Systems Findings
To lower building´s energy demand, in addition to implementing passive approach
strategies, buildings should also rely on improving energy efficiency of systems. In
residential sector, most energy consumption is due to systems used for ambient heating
and cooling (much smaller than heating in terms of annual energy used) and district hot
water (DHW). Lighting together with other occupants related electric use, despite of not
being considered in most building codes, may also play represent a significant amount of
the total energy use. With respect to the energy efficient systems for ambient heating
and cooling, the investigated projects make use of low exergy systems in the form of
radiant heating (
EnergyFlexHouse
,
Leafhouse
and
Lima
) and cooling (
Lima
), and
efficient mechanical ventilation through air heat recovery (virtually all buildings) (Fig. 6).
On the other hand, low power lighting, energy efficient electrical equipment and load
management system are also used as strategies for lowering all building´s energy
demand, despite of the fact that their clear advantages are yet to be proved (Musall and
Voss 2012). Information on the use of these strategies in the buildings under analysis is
synthetized in figure 6.
0.46
0.41
0.52
1.07
0.47
0.56
0.59
0.74
0.87
ECOTERRA
ENERGYFLEXHOUSE
LEAF HOUSE
LIMA
PLUS ENERGY HOUSES
PLUS ENERGY SETTLEMENT
RIEHEN
RIVERDALE
LIGHTHOUSE
