Low energy homes
It is said that around 70 per cent of buildings in the UK that will exist in 2050 have already been built. Yet the UK has long had a reputation for cold and draughty buildings. In essence this means that for buildings, and homes, to become low-energy means that a huge amount of retrofitting, specifically to improve insulation and eliminate draughts, needs to be done. There are many ways to do this including cavity wall insulation, loft insulation, double (or triple) glazing in windows and doors, and underfloor insulation as well as sealing gaps around doors and windows that allow draughts. This is explained in my book, as illustrated by the sample text in the opposite panel.
Although the energy consumption of homes can be greatly decreased by retrofitting, even better results can be obtained in new build homes which incorporate the latest materials, technologies and building standards such as the Passivhaus standard from Germany. After a series of ad hoc improvements to my own home the end result is that I still use about four times as much energy per unit area of floor space as a Passivhaus home. Given that a Passivhaus uses almost no heat energy (it takes heat from the occupants and their activities - cooking, bathing etc.), and therefore doesn't require a central heating system, then the extra cost of the construction is soon offset by the savings made from the almost complete absence of heating bills. I describe a visit to a Passivhaus in my book from which the text in the opposite panel comes. |
"Most of the changes that save on emissions are to do with saving on heat losses in colder weather. The Royal Institute of British Architects (RIBA), in their Climate Change Tools package of guidance documents, points out that a home can gain and lose heat in several ways. Obviously heat is gained through the heating system but other contributions come from passive solar gain, cooking, lights and appliances, the occupants and the use of hot water. About half the heat is lost through the fabric of the home (roof, walls, floors and openings) but heat is also lost through ventilation and air leakage (about one third) and what are described as thermal bridges (about one fifth) which are points of low thermal resistance in the structure around junctions (such as gaps in the insulation) and openings."
"In recent years energy efficient homes have been constructed to other standards which were initially developed on the continent of Europe. Perhaps the most well known is the Passivhaus standard. It was developed in Germany in the early 1990s by Professors Bo Adamson of Sweden and Wolfgang Feist of Germany and the first dwellings to be completed to the Passivhaus standard were constructed in Darmstadt in Germany in 1991. The Passivhaus aim is to build a house that has an excellent thermal performance, and exceptional air-tightness with mechanical ventilation. Because of the high thermal insulation a traditional heating system is no longer considered essential. The annual heating demand of a Passivhaus building is less than 15 kWh per square metre of floor area meaning that annual fuel costs are reduced by a factor of at least five. The Passivhaus Trust says “Evidence and feedback to date shows that Passivhaus buildings are performing to standard, which is crucial, given that the discrepancy between design aspiration and as-built performance for many new buildings in the UK can be as much as 50-100%.” The Trust estimates that globally 30,000 houses have been built to the standard." |
Links to low-carbon retrofitted homes
Superhomes in UK: www.superhomes.org.uk/ A retrofitted home in the New Forest: nfgp.org.uk/way-beat-climate-change/ |