Investigations of building energy use have often concentrated on heating energy, which dominates total primary energy consumption in moderate or cold climatic zones. Today, there are built examples available for both residential and office building types, which demonstrate the feasibility of reducing heating energy demand almost to zero at little extra cost. Even rehabilitation of buildings to passive energy standards is possible using highly efficient glazing, excellent insulation and heat recovery for ventilation needs. Calculation methods for heating demand are available and standardized on a monthly energy balance level.
In contrast, energy consumption for electrical appliances and lighting and for summer cooling has been less analyzed and regulated, although electricity demand has risen strongly in the last few years and high thermal loads in buildings have led to increasing installation capacities of electrical cooling equipment. The loads are partly due to the continuing attraction of highly glazed buildings, where the prevention of solar irradiance transmission is difficult, but also to rising internal loads through computer equipment, electrical lighting and other appliances. Chapter 1 describes the current status of building energy performance and ongoing standardization processes. Measured consumption data for both the residential and commercial sectors show typical consumption distributions and user influence on building performance.
The analysis then proceeds in Chapter 2 to how summer cooling loads can be reduced through sustainable building design. The performance of highly glazed fac¸ades often used in modern office building projects is analyzed in detail. The total energy transmittance of single and double fac¸ades with sun shading systems determines the external cooling loads of a building. It is shown that low-energy transmittance and a good thermal separation between the outside and inside are possible, but that ventilation gains occur if the fresh air is taken directly from a double fac¸ade.
Depending on the climate and building construction, a cooling energy demand often remains, which can be covered by low-energy or active cooling systems. The possibilities of supplying cooling energy are investigated in terms of rising primary energy consumption. First the limits and potential of passive and fan-driven hybrid night ventilation strategies are analyzed. Two well-monitored case studies of office building projects in Germany are presented in Chapter 3, which show the possibilities
today for new and rehabilitated buildings to reduce primary energy consumption for cooling (and heating) to a minimum. Night ventilation results demonstrate the need for very high air exchange rates for effective cooling
- 1 Energy Demand of Buildings
- 2 Fac¸ades and Summer Performance of Buildings
- 3 Passive Cooling Strategies
- 4 Geothermal Cooling
- 5 Active Thermal Cooling Technologies
- 6 Sustainable Building Operation Using Simulation
- 7 Conclusions