Upgrading an existing house, rather than starting from scratch and building a new one is usually considerably more difficult for three main reasons
- historical building technologies may not lend themselves well to upgrading, especially around insulation and air tightnessA measure of how leaky a building is to air. In other words, how draughty it might be. There are now standard fan pressure tests to check how air tight a house is and the Building Regulations have minimum standards for all new houses (L1A – Conservation of fuel and power in new dwellings (England)). A much higher degree of air tightness is covered by the Passivhaus standard
- obtaining building materials which match existing ones may prove difficult
- there may be planning restrictions on what you can do, e.g. with listed buildings or conservation areas.
Given that the rate of replacement of old buildings with new ones is very slow (maybe 1% p.a.) then the challenge of upgrading the older ones becomes paramount. Leading the field at the moment are countries like Sweden, Germany, Austria and Switzerland where the Passivhaus standard is starting to be applied to existing buildings, including buildings of historic importance.
Here are some points to consider if you are dealing with a retrofit situation
- Possible standard to aim for
- current building regulationsThese are the mass of regulations that cover safety, health, welfare, convenience, energy efficiency etc. in the way buildings are constructed. Not to be confused with Planning consent (which is more to do with whether you can put up the building in the first place). See more on the regulations
- Passivhaus EnerPHitthe Passivhaus standard as applied to refurbishment of an existing house. It makes allowance for the difficulty of bringing older properties up to a high thermal standard. see Passivhaus refurbishment standard
- Potential to make major improvements to the design
- A Pattern Language
- Lifetime homes"Lifetime Homes make life as easy as possible for as long as possible because they are thoughtfully designed. They provide accessible and adaptable accommodation for everyone, from young families to older people and individuals with a temporary or permanent physical impairment". See the Lifetime Homes page and the Lifetime Homes Foundation web site
- Alterations and fashion
- Disabled access
- Air tightness and how to achieve it
- Thermal massthis is about how much heat something can absorb - so it involves its specific heat capacity and its volume. It can be useful for levelling out the peaks and troughs of temperature within a house. See the page on thermal mass may be a quality worth exploiting
- Choice of fuel
- Materials compatibility. Traditional building methods may not be compatible with modern materials. There are several things to look out for.
- lime mortar is softer than cement mortar and allows for a degree of movement.
- traditional timber frame structures may move considerably with the seasons, particularly with changing humidity levels. It is important to allow for this.
- there may be situations where it is important to allow interstitial condensation to escape.
- The potentially tricky relationship of extensions to an existing building
- Potential for energy harvesting
- Potential for water conservation / rainwater harvesting
There is a considerable amount of information about retrofit at the low energy buildings database. These are mainly social housing examples but there’s lots of useful technical information.
Superhomes"Opening doors to low energy refurbishment" The homes, which achieve at least 60% less CO2Carbon dioxide is a gas which is given off when carbon based materials such as fossil fuels (coal, oil, and natural gas) are burned. It is called a greenhouse gas because it works like the glazing of a greenhouse and causes global warming emissions, have open days. see the Supehomes website is a fairly new organisation dedicated to showcasing the best of eco refurbishment. Exemplar houses are open to the public at least one day a year.