18 Oct Energy efficient buildings
Belgium Academies (ARB) 2010
In the industrialized world, residential housing and equivalents consume up to 40% of the annual total end energy use. The major part in cool and cold climates goes to heating, though in terms of percentage the share of domestic hot water, lighting, function and cooling increases when the heating needs diminish as a result of higher energy efficiency. By goal-oriented design – compact, smart glass use, very well insulated, airtight – buildings now allow important savings in heating without jeopardizing usability. Since 1973 energetically better construction has evolved from “insulated” over “energy efficient” to “low energy” and, recently, “passive quality”, “zero energy” and “plus energy”. In both last cases, a building produces as much or more energy through photovoltaic cells than it consumes on an annual basis. Anyhow, if applied on a large scale, both concepts will demand a complete transformation of the electricity grid, from passive to smart. Also, contrary to low energy buildings, passive, zero energy and plus energy buildings are beyond the economic optimum.
The EU decided to decrease energy consumption in 2020 by 20% compared to a business as usual scenario, to reduce greenhouse gas emissions by 20% in 2020 compared to 1990 and to increase the share of renewable sources in the energy production to 20% by 2020. Even if from 2009 on all new construction would be of passive quality, 20% less consumption in the built environment will not be achievable by 2020. Moreover, the extremely stringent conditions in terms of energy use for heating in passive buildings have as a consequence that domestic hot water, lighting, function and cooling become the largest consumers, typically in the form of electricity, which weighs heavily in terms of primary energy (_ 2,5). And, energy conservation when these three are at stake is not easy. The only way out in the years to come is, aside of imposing performance requirements at the level of the economic optimum for new construction (E60, K30), promoting with all means energy efficient renovation, energy efficient lighting and energy efficient appliances.