Passion for passive

WITH their interlocking polystyrene block construction, the walls of the house at 5 Webster Pl went up in a week.
The four-bedroom house is no lightweight though - those 240mm thick walls are reinforced with steel and filled with concrete poured into them from the top.
The house is a prototype for a Wanganui company positioning itself at the forefront of the coming revolution in green building.
In April Jon Iliffe and his wife became equal partners with builder Baden Brown and his wife in Eco Build Developments Ltd. They have developed the eHaus brand and hope to spread the idea of low energy green housing through a trust and a through starting their own franchise.
As a first example, Baden Brown Builders are building an energy efficient house in the new Lithgow Dr subdivision on St John's Hill. It's due to be finished in February.
The partners are looking to sell it for $590,000, to someone who will let them monitor its energy use for two years. The idea is to cut heating and other energy costs to almost nil - and they want to make sure they have really done that.
They are using the "passive house" ideas of Dr Wolfgang Feist. The first PassivHaus was built in Germany in 1991, and he still lives in it.
Mr Iliffe, a mechanical engineer, studied the house designs while in Europe for 18 months working for Rolls Royce. He returned to Wanganui in February and he and Mr Brown joined forces.
The Webster Pl house is north facing to capture the warmth of the sun. It will be well sealed and have wool insulation, the 240mm walls and double-glazed windows to keep the heat in.
The window frames will be aluminium, with an air gap between layers to prevent them leaking heat to the outdoors.
Natural light will come from the windows and a kitchen skylight. Ventilation will be provided by a low energy system that extracts the heat from indoor air and adds it to fresh air for circulation.
A 10,000 litre water tank will store water off the roof and the household will use it for everything except drinking. Hot water will be provided by a solar system on the roof, and any heating by an efficient pellet burner.
Mr Iliffe said this would probably only be needed for a couple of hours each evening during the two coldest months.
The Eco Build business partners are both Christians and want to spread the word about green building.
"Making money isn't the be-all and end-all for us. Building low energy houses really fits with who we are as well," Mr Iliffe said.
His business partner Baden Brown is in India at the moment, with 14 other volunteers, on his third trip to rebuild a village shattered by the 2004 tsunami.
The two men are doing a Passive House Design course at Auckland's Unitech.
When they have finished they will be able to look at the plans for any house and calculate whether it will meet the demanding passive house standards.
For more information, see www.ehaus.co.nz.
The Chronicle plans to check out the house as it progresses, and show some of its energy saving features.