The Active Solar-House
Robert Hastings, Univ. Prof. Emeritus
Architecture, Energy & Environment Ltd.
Abstract: Demand is growing for housing requiring very little purchased energy and providing superior winter and summer comfort. Three approaches can achieve such superior performance:
Approach 1: Investment in extreme insulation, elimation of thermal bridges, super windows and heat recovery ventilation. This is the basis for houses carrying the labels: "Passivhaus", "Minergie-P" or "KlimaHaus-Gold", to name a few examples. The cost of energy saved from the last increment of conservation is, however, very expensive.
Approach 2: Investment in PV to achieve a "net zero energy house". Such houses are not zero energy houses. They require energy in winter for heating and all year for hot water, while the bulk of their energy is generated in summer. This highly seasonal PV energy with a large primary energy credit "offsets" annual energy demand, but demand is momentary not annual. The investment is profitable for home owners only with generous subsidies or high utility buy back tariffs. However, the costs must be carried by all tax-payers or electricity consumers.
Approach 3: Investment in a balance of conservation, solar thermal and lastly PV. The heating demand is drastically reduced and solar can largely cover demands for space heating in spring and fall and domestic water in spring, summer and fall. When the budget still allows, PV can also be added, or added at a future date when PV will be less expensive.
Realistic targets for an active solar house in middle Europe are a total annual primary energy demand of 120 kWh / heated floor area and 35 to 50% solar coverage of space and water heating demands. Passive solar gains are an important asset to reduce heating demand and enhance living quality. With the thick insulation and intense solar use, summer comfort is an important. It is solved with effective sunshading and strategic natural ventilation.
Technical advances in insulation systems, window constructions, glazing systems, solar thermal systems and controllers offer exciting new design possibilities for building active solar houses. Three example houses from Switzerland, Germany and Austria illustrate this balance approach to high performance housing.
Brief Biography of the Speaker:
Robert Hastings, Prof. Emeritus of the Donau University-Krems Austria is an energy consultant and architect. His firm, AEU Ltd won the 2007 United Kingdom Energy Institute Environment Award, and in 2002. The firm, together with a partner firm won 1rst Prize in a European Solar Design competition for a solar housing project in Herten, Germany. Mr. Hastings has lead three programs of the International Energy Agency in the fields of sustainable buildings and is a former leader of the SolarArchitecture research and demonstration programme in Switzerland as a scientific adjunct on the ETH-Zürich. He has co-edited/authored books from publishers in London, New York and Heidelberg. It has been a pleasure for him to be a keynote speaker at congresses of EUROSUN; ISES, PLEA, OTTI, CISBAT and the PHI in Europe, China and North America. His greatest pleasure is sitting down with a client or students to review a building project regarding both energy and architectural aspects. He is a firm believer that the quality of life must be the key design criteria, be it for the design of a chair, house, office or school.