Two low energy homes built to Passivhaus standard – which are so energy efficient they require no heating and there is only a towel heater in the bathroom – are a visionary part of the Janet’s Corner development in Castletown.
The Passivhaus is heated ‘passively’. The building is super-insulated, with triple-glazed windows, and uses whole house ventilation and heat recovery to keep the temperature even throughout, and at a comfortable level.
‘It’s a ventilated box,’ said Department of Infrastructure architect John Payne. ‘The occupants provide the heat. Also there is heat from electronic devices like the TV, etc, and solar gain, plus there are bigger windows facing south.
Careful detailing and construction has been used to maximise the airtightness of the building.
If the house is unoccupied for a lengthy period, turning the oven on for just half an hour would generate enough heat to reach a comfortable temperature.
In the summer months, a pergola-type structure protects the property from direct sun and windows can be opened to vent trapped heat.
The Passivhaus concept was introduced to the department in 2010 by Dave Watterson, who had lived in Sweden.
The system had been developed in the 1990s by two physicists – Dr Wolfgang Feist and Dr Bo Adamson – and is now used in 30,000 homes worldwide.
‘The software that was developed proved to be so accurate, it is almost forensic in the level of attention to detail,’ said Mr Payne. ‘Other systems fall short of that, that’s why there is so much excitement about it around the world.’
Although the construction costs are higher (an exact figure is hard to pin down as this was a pilot scheme), this is recovered through savings in energy bills during the life of the building
Another fringe benefit – as experienced by a council in Essex – is that tenants living in public sector Passivhaus housing keep up with the rent. In Essex, they found rent arrears came down significantly because previously tenants were using their money to pay the heating bills before the rent.
Infrastructure Minister Phil Gawne said: ‘I am passionate about protecting the environment and this latest development could point the way towards a more sustainable way of building affordable housing in the Isle of Man. I wish to congratulate all those involved, in particular the main contractor Tooms Brothers.’
Project manager and DoI architect Phil Halliwell said: ‘A significant amount of time and effort has been invested in this project with the aim of testing the benefits of building to the Passivhaus standard in the island.
‘The DoI will be monitoring energy use and environmental conditions in the properties during their first few years. Their performance will also be scrutinised by an independent Passivhaus certifier.’
He added: ‘We will also be looking at whether these homes are suited to the Isle of Man’s climatic conditions and meet the requirements of those seeking affordable housing.’
