Playing by Passive house rules pays off for self-builders

For Tim and Marilyn Larner, the dream of self-building came long before Grand Designs made it a commonly-held ambition.

“The seed was sown in the 1970s when we saw a house that Marilyn's aunt and uncle had built,” says Tim.

Busy with work and bringing up their children, the couple, both now 65, opted for stability and spent 25 years in the same Victorian semi in Harrogate before finally putting their plan into action and building not just one but two homes.

In the final stages of completion, the properties are on Bogs Lane, between Harrogate and Knaresborough and close to Nidd Gorge. Both are so energy efficient that one costs nothing to run and the other next-to-nothing.The couple's own home is set to be the first-ever certified Passive house in the Harrogate area with an almost identical five-bedroom eco home on the neighbouring plot. The latter is for sale at £625,000 through Myrings with a rare AA rated energy performance certificate after an eight-month-long build using the latest innovative off-site construction methods and energy-efficient technologies.

“We went down the Passive house route for our own home after seeing Marilyn's cousin's property, which was one of the first certified Passive houses in the UK. It was impressive and it makes sense. The house for sale is also built using Passive house principles,” says Tim, a retired local authority transport planner whose biggest challenge was finding a suitable plot at the right price

It took eight years of searching to find the farmhouse with planning permission for two houses in the grounds. “The beauty of it is that we have been able to live in the farmhouse and be on site while the new properties have been built. That has enabled us to be very involved with the build. The only conundrum was what to do with the second plot. Rather than sell it on we plucked up the courage to develop it ourselves as we didn't want to run the risk of living next to a building site for years,” says Tim.

The construction method was chosen after extensive research over the years, including reading self-building magazines and attending shows. Lancashire-based Build-a-Kit won the contract.

The company constructed the timber frame in its factory in Nelson, Lancashire, along with the insulated panels, which have been clad in larch.

After concrete slab foundations had been laid, the prefabricated components were transported to site and the buildings were erected within three days.

Founder Bill Richardson, who launched Build-a-Kit after working for a developer who used timber frames and seeing similar builds while living in Australia, says: “It's a hybrid system where the frame, insulated panels and service batons for running wiring through are made in the factory. We also make the roof inside and clad it with panels and batons to attach the tiles to.

“The plumbers, electricians joiners, plasterers and bricklayers go on site to do the rest.”

The cost ranges from £80,000 for a basic two-bedroom house to £450,000-plus for a detached property. Time taken to complete varies from six months upwards.

“We have been really pleased with Build-a-Kit and it was an amazing sight watching the houses go up so quickly with a 40-tonne crane lifting everything into place. We opted for off-site construction because the quality control is better and it is not weather dependent,” says Tim, who had a full-service contract which saw Build-a-Kit bringing in its own tradespeple to complete the interior fit-out.

The cost was equivalent to a conventional build. Holly Garth, the property now for sale, is far superior to most new-build homes. The annual running costs are expected to be just £320 thanks to its air-tightness and insulation far in excess of Building Regulation requirements.

In keeping with Passiv house ideals, the windows on the colder, north side of the property are smaller than those on the south side, which are larger to make the most of solar gain.

A mechanical heat recovery and ventilation system ensures that damp, stale air is removed from the rooms and fresh, filtered air is brought in.

“The house is heavily insulated and there are no trickle vents and no thermal bridging, which means that cold air can't get in. A MHRV unit is essential and means that good quality air flows around the house,” explains Tim.

He and Marilyn also installed an air source heat pump to run the underfloor heating while solar panels generate electricity and attract a government feed-in tariff.

Their own home is almost ready to move into and is even more efficient after fulfilling the stringent criteria for Passive house certification. It has triple-glazed windows and even more insulation and is so warm and air-tight that the only form of heating is a 1.5kw fan powered by electricity generated from photo voltaic panels. The solar power is stored in batteries in a small plant room, so the Larners will be totally self-sufficient.

“Our house should cost nothing to run. In fact, it will make money thanks to the government feed-in tariff payments from the solar panels,” says Tim.

Although the two new houses look identical and have the same square footage, they feature different layouts. Holly Garth is laid out as a traditional family home while the Larners' house is future-proofed for old age.

Tim adds: “We built this as our forever home and we will never forget the morning it was delivered and constructed. That was the most exciting day of our lives.”

*For sale: This eco home between Harrogate and Knaresborough is £625,000. It comes with a rare double A EPC rating and has a living kitchen, sitting room, snug/home office, cloakroom and utility room. The first floor has a bathroom, three double bedrooms and two en-suites plus a dressing room. The second floor has two further bedrooms and en-suite shower room. There is also walk-in, under-roof storage.

Contact: Myrings, tel: 01423 01423 566400.