3 PRINCIPALS OF CLIMATE NEUTRAL BUILDINGS
From “The Ecology of Building Materials” Second Edition, 2009, Bjorn Berge
It is possible to construct buildings that are climate neutral throughout their entire lifecycle. This requires that we take into consideration both the materials’ aspects as well as operational energy use. Such buildings will have both a climatic ‘debit’ and ‘credit’ account, and must be based on the following principles.
FIRST PRINCIPLE: CHOOSE LOW IMPACT MATERIALS AND CONSTRUCTIONS
All materials chosen must have minimal fossil energy demand in production and transportation. Products with chemical emissions of greenhouse gases should be omitted.
Using timber instead of concrete or bricks, for example, reduces emissions from the materials production by approximately 1 kg of CO2 per kilogram of timber used (Kram, 2001). Even with fairly moderate substitution, one may reduce the climate emissions by some 20 to 30% (Nemry et al., 2001; Pingoudet al., 2003;Thormark, 2007). Over 50% is possible given less conventional materials and solutions (Goverse et al., 2001).This also requires choosing materials that are easy to maintain and to modify and recycle.
One should also ensure that the combustion value of biological waste materials is energy-recovered so a store place fossil fuels. In the case of materials based on fossil resources, in particular plastics, controlled dumping may be the best solution from the climate point of view, since energy recovery from these results in emissions of greenhouse gases corresponding to burning the same amount of fossil fuel. Use of lightweight materials will reduce transport related emissions. It is estimated that 1 kg of wood can replace 3.6 kg of concrete or brick (Pingoudet al., 2001). On the other hand, the thermal capacity provided by the heavy materials will reduce this advantage somewhat. This depends to a large extent on factors related to construction methods, local climate and building type.
SECOND PRINCIPLE: REDUCE ALL OPERATIONAL ENERGY, IN PARTICULAR THAT BASED ON FOSSIL FUELS
Operational energy includes space-heating, electricity and hot water. It is important to remember that choice of the best strategies will often depend on very local climatic factors. For example, in windy coastal regions improved air tightness measures will have far more e¡ect than extra insulation.
THIRD PRINCIPLE: MAXIMIZE STORAGE OF CARBON
Use as much construction material as possible that is of plant origin ^ in practice mainly timber ^ and in ways that ensure long life as well as reusability (Figure 2.2). Even in Finland, where timber construction is already dominant, it has been estimated that use of timber in construction could well be increased by 70% (Pingoud et al., 2003). A potential of up to 550 kilograms of timber products per square metre of £oor area is achievable in small houses. This is based on the use of massive timber constructions in walls, doors and roofs. For larger building types, 300 to 400 kg/m2 may be realistic,
Bjorn Berge, 2004