Energy sieve

An energy sieve refers to a building with very poor energy performance, typically rated F or G on the EPC scale, with consumption exceeding 400 kWh/m2/year. In Belgium, these buildings still represent a significant share of the housing stock, particularly pre-1970 constructions. Regions impose progressive renovation obligations: in Flanders, sold properties must reach label C by 2030; in Wallonia, minimum label D is targeted. Energy sieves suffer a significant market discount (15 to 25% less than a well-insulated property) but can represent an investment opportunity if renovation works are well planned and subsidized.