40% House

Mark and Alice Luntley have systematically improved their poorly insulated house as part of a downscaled and low carbon lifestyle. Their approach is an excellent case study in the simple and practical changes that could be applied across all houses of this age and type.

The house was constructed in 1982 by Linden Homes, a speculative developer, as part of an estate in Oxpens, Central Oxford. The house was constructed to the very poor energy standards that applied prior to the 1982 building regulations, with only thin loft insulation, no cavity insulation and single glazed windows. The house had two substantial benefits- it was mid terrace and had an unobstructed southern aspect at the rear.

Why did they want to do it?
Mark and Alice are both motivated by a deep concern about climate change and a strong moral motivation to reduce their emissions and their waste. As Mark says “we didn’t want to be armchair campaigners who just talked about what government’s should do”. The renovation of their house provided the perfect opportunity to put their principles into practice.

About the renovation

Heating
The priority was set by the need to replace the original boiler, which was reaching the end its life and was close to failure. They took the opportunity to install a solar-combi system which achieves high boiler efficiencies but is still rare in Britain. The boiler is an Atmos Mono Solar, a Dutch condensing combi boiler designed to function with the variable water temperatures of solar system. The flat plate solar system warms a 100 litre heat store which then preheats water entering the boiler.

They took the advantage of the heating upgrade to seek out other efficiency improvements. They replaced two undersized radiators and fitted and carefully set good quality Thermostatic  Radiator Valves on all radiators. They also installed new electronic controls which allowed full programming (the old system had run on a timer and single thermostat).

Insulation
They added 100mm of Thermafleece sheepswool insulation over the 70mm of rockwool that was already in the loft. They filled all external wall cavities under a subsidised local council scheme. At the same time they persuaded the installers to insulate the cavities in the wall and ceiling of the garage. As is typical of developments of this period, the garage is built into the ground floor of the house. The garage walls, are  therefore external surfaces and a major source of heat loss. Early next year a builder will line the garage with a further layer of insulation.

Conservatory and porches
Mark and Alice commissioned an architect-designed conservatory for the south facing rear of the house. To maximise performance, the glazing is located solely on the south wall of a well-insulated shell: the side walls are built of brick with 100m insulation and the floor has 100mm of insulation under terracotta tiles. In the spring and autumn the sliding doors are opened to allow the warm air to enter the house. In summer electronically controlled vents in the roof are opened to reduce solar gain. Despite this the conservatory is still too hot in summer and they intend to fit solar blinds next year. Otherwise they are delighted with the conservatory which Mark calls “a little bit of Spain”.

Pictured: The conservatory on the south-facing side of the house.
 
They have obtained planning permission for a porch on the north facing front of the house which will prevent cold air forcing its way into the house when the front door is opened. They intend to build it in 2006.

Conservatory and porches 
Mark and Alice have installed efficient appliances, compact florescent lighting and a heat exchanging fan in the bathroom. They specified a solid wood kitchen (chipboard has high embodied emissions) and a Swedish Ifö Cera toilet, which uses only 2 to 4 litres of water per flush (45% less water than the conventional British models).

Other aspects of a low carbon lifestyle
Mark and Alice see their house improvements as one component of an integrated strategy for reducing their contribution to climate change. They replaced their two cars with a Toyota Prius hybrid and now have all their holidays in Britain. Probably the greatest single cause for their emissions reductions has been their decision to live within walking distance of work- Alice even changed her job so that she could avoid commuting.

What were the main obstacles they encountered?
They said that they had no problem finding an architect who could give them what they want, but that they hit a major problem with finding skilled contractors who were competent and willing to implement the plans. They note, though, that this is a common problem in Oxford, even for more conventional projects.

They have also had some major performance problems with their boiler which has required six repairs during its warranty period. Mark says that he has heard good things about the Atmos make and thinks he might just have a ‘duff Friday afternoon boiler’.

How did they find out what to do?
They started by commissioning a full energy survey, which identified the main sources of heat loss and the priorities for renovation. Their further understanding of the things they might do came from the solar installers, the architect and general reading. They recommend Factor Four by Amory Lovins, which Mark says was a major inspiration, and  the Natural House Book from the Centre for Alternative Technology.

Three top tips
1. Keep it simple. There are too many people trying to sell you fancy systems and products. Keep to what is tried and tested.
2. Take things slowly. It takes time to pull together the contractors and the various parts, so start with an overall plan and implement it in incremental stages.
3. Change the way you live. Make sure that the changes in the house are part of a wider level of behavioural change- in terms of how you live in the house and where you live.

What were the improvements in energy performance or the carbon savings?
Electicity consumption has already fallen by 45-50% Mark is preparing a full energy audit. This will be added later.