Jeff and Rose Tanner have built a low-energy home, designed to last a lifetime, for just £175,000 — here, they reveal the nuts and bolts of how it all works. Includes advice on heat pumps, solar thermal, greywater recycling, central vacuum system and more.

Jeff and Rose Tanner are, in many ways, typical of today’s self builders, being a little older than they used to be (they are both nearing retirement) and, perhaps typically of their generation, worried about rising fuel prices too. So it seems natural that they would be interested in building a low-energy home.

Milton Keynes, where their new home is situated, has a long pedigree of promoting both self build and low-energy construction. It has always prided itself on asking developers to beat the Building Regulations, and is home to a number of experimental low-energy homes. It has also hosted three national housing exhibitions, and the Tanners’ house is actually located on one of these sites. The plot had once been home to an information centre and in the intervening years it had fallen into the hands of English Partnerships, who decided to sell it off. For one reason or another, it wasn’t terribly well advertised and rather than being marketed locally, it was auctioned off in London in February 2009. Jeff and Rose spotted the potential and won the bidding, picking it up for just £85,000 — proving that there are still some bargains to be had in the property market.

One of the requirements stipulated by the council was that the new house should meet Level 3 of the Code for Sustainable Homes, which specifies an energy-efficiency standard as well as a number of other factors. The Tanners had no problem with this as they wanted a low-energy house and they decided to set the standard somewhat higher at Level 4. “Early on, we decided that it would be timber frame because we thought that this would be the simplest way to achieve the insulation levels required,” says Jeff. “We came up with a simple design that would meet our needs now and into the future. The Code for Sustainable Homes is about more than just energy efficiency and the house is also designed to be wheelchair-friendly (the Lifetime Homes standard) and to be water-wise. It also had to be simple to build.”

(MORE: Code for Sustainable Homes Explained)

The project ran throughout 2010 with the timber frame going up in April. Jeff and Rose moved in in February 2011, just two years after they purchased the plot. Here is a summary of how it was built:

Heating and Ventilation

The house has no conventional heating system at all; nor does it have any provision for that eco-standby, the wood-burning stove. “Instead, I have designed a small radiator to pre-heat the air coming in through the ventilation system,” says Jeff. “I estimate it will deliver 3kW of heat, which will be more than enough to keep the house warm on the coldest of days. If all else fails, there will be back-up convector heaters to take the chill off, but the intention is that we shouldn’t have to use these at all.”

Such a low-energy near-airtight house requires adequate ventilation, so the Tanners also installed a mechanical ventilation system with heat recovery (MVHR) to distribute fresh air around. Hot water is provided by a mixture of solar heating and electricity via an air-to-water heat pump.

Wiring

As well as standard electrical wiring, the house is wired for broadband and audio (with ceiling speakers located in the master bedroom and living room), digital radio and Sky TV, plus various controls for solar panels and energy sensors, water management systems, smoke detectors and a spur for a chairlift.

Lighting

All the lighting is low energy, mostly compact fluorescent lamps (CFLs). In the garden, the exterior lights are LEDs using just 1.2 Watts each.

Lifetime Homes

Over and beyond the Building Regulations, the house is readily adaptable for a wheelchair user, meeting the Lifetime Homes standard (see lifetimehomes.org.uk for full details). It has wetroom bathrooms on both ground and first floor, with provision for a hoist and lift. It is also built with attic trusses which will allow easy conversion of the loft into living space should the need arise. “Apart from the small additional cost of making a wetroom, which typically requires tanking the whole room, the additional cost of all this work is lost in the timber frame quotation,” explains Jeff.

Bathrooms

There are three upstairs bathrooms, including a wetroom and a downstairs toilet/wetroom. In order to meet the water efficiency standards, the toilets are dual flush with a maximum flush of just 4 litres, and the showers have flow restrictors.

Rainwater and Greywater Recycling

The house also has a homemade rainwater and greywater recycling system with tanks and pumps and controls all put together by Jeff (he’s an engineer who loves this sort of stuff). “The main rainwater tank, situated under the garden, collects water off the roof after filtering out the leaves. The water is pumped up into the loft and is used to feed the washing machine, the outside taps and the loft greywater tank, which in turn feeds the toilets,” he explains. “The greywater is collected in the garage in a smaller tank which is fed by the water running out of the bath and showers.”

Domestic Hot Water

Hot water is stored in two Gledhill cylinders, located in the loft. The primary cylinder holds 215 litres, and the secondary 150 litres. “The idea is for the secondary cylinder to store solar water and to pre-heat the mains water coming into the main tank, so that in winter we only have to heat the main tank,” says Jeff. “There is a solar hot water panel assembly on the roof above and also an air-source heat pump out in the garden, both of which take priority towards heating the hot water. If all else fails, there is an immersion heater to take over.” The house has no mains gas supply at all.

Central Vacuum System

A Beam central vacuum system has been installed, running throughout the house. There are four inlets altogether, plus another in the garage where the motor and the container are located. The one in the kitchen is located down at floor level (hidden under the units) so that Rose and Jeff can just brush bits into it.

Code for Sustainable Homes

The house is designed to meet Level 4 for the Code for Sustainable Homes. In order to do this, the Tanners had to employ a Code Assessor (Cliff Bull of Celleb) at a cost of £1,500. “Not only did we have to meet stringent energy and water efficiency targets, but also various other criteria,” explains Jeff. “The house had to be Lifetime Homes compliant, which involved far more than just having level doorways and easy-to-reach sockets and light switches. We had to build in provision for a hoist to take a chair into a wetroom, and leave a space where we could, in future, fit a lift if required.” The couple also had to provide a Designated Outdoor Drying Area and a storage space for bikes, which is currently used as a garden shed.

One of the more interesting requirements was to meet the Secured by Design standard, which involved a lot of lock checking mostly, but also the recommendation that the garden fence should have a trellis at the top, to make it harder to climb over and easier to see who was on the other side. Visit securedbydesign.com for more information.

(MORE: CSH: Meeting the Requirements)

How the House was Built

Jeff project-managed the build throughout using a variety of subcontractors. In all, he probably put in around 180 days’ work, including evenings, weekends and holidays and, after January 2011, full time as he had retired. Rose works full time as a teacher but she too contributed another 25 or 30 days to the project. “But it was worth every hour spent, as we have saved a lot of money and have a home we can be proud of for years to come,” concludes Jeff.

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