IEA Solar Heating & Cooling Implementing Agreement - Task 13 (Solar Low Energy Buildings) was an international effort organised by one of the International Energy Agency's Implementing Agreements to build several solar low-energy houses. This took place between 1989 and 1993(?). The Implementing Agreement for a Programme to Develop and Test Solar Heating and Cooling Systems is one of 40 research and development and deployment programmes, which are at the core of the IEA's International Energy Technology Co-operation Programme.
The idea behind Task 13 was to push construction technology towards its limits to achieve the lowest possible total purchased energy consumption. Task 13 was part of the IEA Solar Heating and Cooling Programme, to test the designs and techniques, and to monitor their performance.
On average, the houses were designed to required 44 kWh/m², 75% lower than the average 172 kWh/m² that would have been required had the houses been built to normal standards. (Analysis of 11 of the houses in use indicated that total savings made in practice was actually 60% ).The 44 kWh/m² resulted from:
The buildings were constructed to be airtight, be superinsulated to roughly double normal standards, and to minimise thermal bridges. Masonry and several timber framed methods were represented, along with a novel steel strengthened polystyrene block walls were used. The Berlin "Zero Heating Energy House" included a 20m³ (700 cubic feet) seasonal thermal store.
The homes in the programme were:
- Pleiade Row House, Louvain-la-Neuve, Belgium
- Brampton Advanced House, Canada
- Waterloo Region Green Home, Canada 
- Kolding Row House, Denmark
- IEA 5 House, Pietarsaari, Finland
- Ultrahouse, Rottweil, Germany 
- Zero Heating Energy House, Berlin, Germany 
- Wish House 3, Iwaki, Japan 
- Urban Villa, Amstelveen, Netherlands 
- IEA Task 13 House, Hamar, Norway 
- Roskar Low Energy House, Sweden
- Duplex in Gelterkinden, Switzerland
- Exemplary House, Grand Canyon, USA
- Exemplary House, Yosemite, USA
Among the lessons learned were that:
- Airtightness was difficult to achieve
- Ventilation systems could suffer from noise and draft problems
- Care was needed to design out summer overheating
- Simple installations and systems were easier for the residents to understand
For a report on the Task 13 findings, see Energy Design Update, December 2003.
- List of pioneering solar buildings
- Passive house
- Low-energy house
- Zero energy building
- Sustainable development