There are myriad opportunities for energy efficiency improvement in buildings (Acosta Moreno et al., 1996; Interlaboratory Working Group, 1997; Nadel et al., 1998) (see Table 3.3). Most of these technologies and measures are commercialized but are not fully implemented in residential and commercial buildings, while some have only recently been developed and will begin to penetrate the market as existing buildings are retrofitted and new buildings are designed and constructed.

A recent study identified over 200 emerging technologies and measures to improve energy efficiency and reduce energy use in the residential and commercial sectors (Nadel et al., 1998). Individual country studies also identify many technologies and measures to improve the energy efficiency and reduce greenhouse gas emissions from the buildings sector in particular climates and regions.⁹ For example, a study for South Africa discusses 15 options for the residential sector and 11 options for the commercial sector (Roos, 2000). Examples of other studies that identify energy efficiency or greenhouse gas mitigation options for the buildings sector include those for Brazil (Schaeffer and Almeida, 1999), Bulgaria (Tzvetanov et al, 1997), Canada (Bailie et al., 1998); China (Research Team of China Climate Change Country Study, 1999); Czech Republic (Tichy, 1997), the European Union (Blok et al., 1996; van Velsen et al., 1998), India (Asian Development Bank, 1998), Indonesia (Cahyono Adi et al., 1997), Mexico (Mendoza et al., 1991), Poland (Gaj and Sadowski, 1997); Ukraine (Raptsoun and Parasyuk, 1997), and the US (Interlaboratory Working Group, 1997; National Laboratory Directors, 1997; STAPPA/ALAPCO, 1999). Below examples are given of three new developments out of many that could be cited: integrated building design, reducing standby power losses in appliances and equipment, and photovoltaic systems for residential and commercial buildings. These examples focus on options for reducing greenhouse gas emissions from the buildings sector in which there has been significant recent research: improving the building shell, improving building equipment and appliances, and switching to lower carbon fuels to condition the air and power the equipment and appliances in buildings. In addition, recent developments in distributed power generation for buildings are briefly described (see also Section 3.8.5.3).

Table 3.3: Overview of opportunities for energy efficiency improvement in buildings (Acosta Moreno et al., 1996; Interlaboratory Working Group, 1997; Nadel et al., 1998; Suozzo and Nadel, 1998).
End use	Energy efficiency improvement opportunities
Insulation	Materials for buildings envelopes (e.g., walls, roofs, floors, window frames); materials for refrigerated spaces/cavities; materials for highly heated cavities (e.g., ovens); solar reflecting materials; solar and wind shades (e.g., vegetation, physical devices); controls; improved duct sealing
Heating, ventilation, and air conditioning (HVAC) systems	Condensing furnaces; electric air-source heat pumps; ground-source heat pumps; dual source heat pumps; Energy Star residential furnaces and boilers; high efficiency commercial gas furnaces and boilers; efficient commercial and residential air conditioners; efficient room air conditioners; optimization of chiller and tower systems; desiccant coolers for supermarkets; optimization of semiconductor industry cleanroom HVAC systems; controls (e.g., economizers, operable windows, energy management control systems); motors; pumps; chillers; refrigerants; combustion systems; thermal distribution systems; duct sealing; radiant systems; solar thermal systems; heat recovery; efficient wood stoves
Ventilation systems	Pumps; motors; air registers; thermal distribution systems; air filters; natural and hybrid systems
Water heating systems	High efficiency electric resistance water heaters; water heaters; air-source heat pump water heaters; exhaust air heat pump water heaters; integrated space/water heating systems; integrated gas-fired space/water heating systems, high efficiency gas water heaters; instantaneous gas water heaters; solar water heaters; low-flow showerheads
Refrigeration	Efficient refrigerators; high efficiency freezers; commercial refrigeration technologies
Cooking	Improved biomass stoves; efficient wood stoves; Turbochef combination microwave/convection oven; high efficiency gas cooking equipment
Other appliances	Horizontal axis washing machine; increase washing machine spin speed; heat pump clothes dryer; efficient dishwashers; consumer electronics with standby losses less than 1 watt; consumer electronics with efficient switch-mode power supplies
Windows	Double and triple-glazed windows; low-emittance windows; spectrally selective windows; electrochromic windows
Lighting systems	Compact fluorescents (including torchères); halogen IR lamps; electronic ballasts; efficient fluorescents and fixtures; HIDs, LED exit signs; LED traffic lights; solid state general purpose lighting (LEDs and OLEDs); lighting controls (including dimmers); occupancy controls; lighting design (including task lighting, reducing lighting levels);daylighting controls; replacement of kerosene lamps
Office equipment	Efficient computers; low-power mode for equipment; LCD screens
Motors	Variable speed drives; high efficiency motors; integrated microprocessor controls in motors; high quality motor repair practices
Energy management	Buildings energy management systems; advanced energy management systems; commercial building retro-commissioning
Design	Integrated building design; prefabricated buildings; solar design (including heat or cold storage); orienta-tion; aspect ratio; window shading; design for monitoring; urban design to mitigate heat islands; high reflectance roof surfaces
Energy sources	Off-grid photovoltaic systems; cogeneration systems

3.3.4.1 Integrated Building Design

Integrated building design focuses on exploiting energy-saving opportunities associated with building siting as well as synergies between building components such as windows, insulation, equipment, and heating, air conditioning, and ventilation systems. Installing increased insulation and energy-efficient windows, for example, allows for installation of smaller heating and cooling equipment and reduced or eliminated ductwork.¹⁰ Most importantly, it will become possible in the future to design a building where operation can be monitored, controlled, and faults detected and analyzed automatically. For large commercial buildings, such systems (which are currently under development) have the potential to create significant energy savings as well as other operational benefits. Two recent projects that used integrated building design for residential construction found average energy savings between 30% and 60% per cent (Elberling and Bourne, 1996; Hoeschele et al., 1996; Parker et al., 1996), while for commercial buildings energy savings have varied between 13% and 71% (Piette et al., 1996; Hernandez et al., 1998; Parker et al., 1997; Thayer, 1995; Suozzo and Nadel, 1998). Assuming an average savings of 40% for integrated building design, the cost of saved energy for residential and commercial buildings has been calculated to be around US$3/GJ (the average cost of energy in the US buildings sector is about US$14/GJ) (Nadel et al., 1998; US DOE/EIA, 1998).

IPCC Homepage