Advanced Houses of the World

The International Energy Agency's Centre for the Analysis and Dissemination of Demonstrated Energy Technologies (CADDET) features 25 such houses in 13 countries in Learning from Experiences with Advanced Houses of the World. While the projects are similar in many respects, the focus varies slightly from country to country. 

Some countries, such as the United States, tend to pay the most attention to reducing operating costs. The three U.S. houses featured-the Idaho Energy Conservation Technology House, the Energy Smart Home in Pensacola, Florida; and Optimar: The Energy Answer Home in Mulberry, Florida-all showcase superinsulation and ground source heat pumps.

Other countries, including the Netherlands, are making a concerted effort to reduce greenhouse gas emissions, using strict building standards, taxes, and research programs. Ecolonia and Scheidam-communities that feature energy-efficient houses, green spaces, and measures to encourage public transit-are part of the Dutch program, which has resulted in the construction of thousands of low-energy houses.

Increasing comfort is a big part of Japan's R-2000 program (modeled after the Canadian R-2000). The energy efficiency of the R-2000 houses means that Japanese residents can keep the house warm for more hours in the day and keep more rooms heated all winter. 

In Switzerland, the biggest impetus for advanced housing is to reduce foreign energy imports. As a result, standard Swiss houses are as energy efficient as the most efficient houses in many other countries. Switzerland has built 30 advanced houses for its Pilot and Demonstration Program.

In Norway, the public is very concerned about environmental conservation, leading to a strong emphasis on sustainable housing. About 36% of the country's national research and development budget is spent on conservation activities. Norway's demonstration projects include the IEA Task XIII: Advanced Solar Low Energy Buildings, which use only 17% of the energy of a typical new Norwegian house.

Canada is leading the way in building houses out of sustainable materials that create a healthy indoor environment. The Canadian Advanced Houses program encouraged building with recycled products and avoiding CFCs. The Canadian Mortgage and Housing Corporation has been promoting good indoor air quality since its Healthy House competition in 1991. 

So what makes an Advanced House? CADDET chose houses that incorporated techniques like superinsulation, ventilation with heat recovery, passive solar design, airtight construction, high-performance windows, transparent insulation, high-performance heating systems, solar domestic hot water systems, integrated mechanical systems, high-efficiency lighting, energy-efficient appliances, photovoltaics, and ecological management strategies. 

How do you prefer your heat loss coefficient-U.S.-style (Btu/h^oF), Japanese-style (kcal/m²hK) or German-style (W/m²K)? Being a German, I have a hard time thinking in terms of the first two units. Luckily, we can use conversion factors to translate one to another. But some units are much more difficult to convert. 

Take Heating Degree Days (HDD), for example. Moscow, Idaho, has 3,600 HDD, using a base of 65^oF (18^oC) over a heating period of seven months (the period used by CADDET for the Advanced House comparison). Hamburg, Germany has 3,837 HDD based on 20^oC (68^oF) with a very different definition of the heating period (the Germans use an eight-month heating period, but days with an average outside temperature of 15^oC [59^oF] or more don't count at all). You can't use a single conversion factor for these-in fact, you would need all the original weather data to figure it out.

Even if this problem were solved, difficulties remain. One involves comparing energy in the form of electricity to that from natural gas or oil. CADDET compared the Advanced Houses based on site (purchased) energy. Thus the Heidenheim House in Germany shows an annual purchased space heating energy use of 59 kWh/m² (one of the 'highest' of the Advanced Houses), while the Idaho House had only 25 kWh/m² of space heating energy use. 

But the motivating factor for the Heidenheim house was to reduce carbon dioxide (CO₂) emissions. Heidenheim has a gas boiler with heat recovery; Idaho, an electric ground source heat pump with electric resistance backup heating. If the electricity comes from a fossil fuel power plant, an evaluation of the two houses based on kg/m² of CO₂ would show a switch of ranking.

For all these reasons, we need to improve the technique for comparing the energy efficiency of buildings. We need an international agreement about format and minimum data collection for monitored Advanced Houses. Besides general indicators (such as heating energy consumption, the efficiency of the mechanical systems, number of occupants, and floor area), evaluation and comparison of the houses should use indicators that respect the targets (like CO₂ reduction) that the projects aimed at.*

Learning from Experiences with Advanced Houses of the World is available for $39 post-paid from the American Council for an Energy Efficient Economy, 2140 Shattuck Ave., Suite 202, Berkeley, CA 94704; Tel:(510)549-9914; Fax:(510)549-9984.

 -Jeanne Byrne
 
 

*Interview with Sabine Busching, Professor, University of Art-Hamburg, Department of Architecture, July 1996.