Passive House And Net Zero: The Zero E House
Earlier this week we brought you the story behind the design that took First Prize in the 100 Mile House Competition, which challenged designers this year to envision a green home built from materials available within a hundred miles of Vancouver, British Columbia. Now we bring you the design that took Second Prize, the Zero E House by Neil Burford and Alex Pearson of Joseph Thurrott Architects of Dundee, Scotland.
These architects envisioned a home constructed of timber, zinc, and polycarbonate cladding, with cross-laminated timber (CLT) structural walls. CLT –which has been used in Europe for a decade or so, but has yet to see widespread use in North America — is an engineered mass timber product that bears little resemblance to traditional wood. It is composed of dense, solid panels of wood engineered for strength through layers of laminations that meet (and in some cases exceed) the performance of reinforced concrete, but with less ecological impact. These walls, combined with hemp fiber insulation (a product of Western Canada, of course), form the tight, highly insulated building envelope necessary to keep heating and cooling costs to an absolute minimum, as per Passive House strategy, while putting less demand on the home's renewable energy systems in order to achieve net zero status.
Electricity here is supplied by a rooftop photovoltaic system, while a solar thermal system meets the household's hot water needs. A cellular foam concrete foundation works hand-in-hand with the home's strategic passive solar orientation, retaining heat gained via the sun during the day and releasing it slowly overnight. Geothermal wells beneath the house, working in conjunction with a ground-source heat pump, cover the final distance in keeping temperatures comfortable year-round. Passive House windows make sure that what small amount of energy is required to heat and cool the home is not expended in vain.
The home makes use of a ventilation system to make sure the home retains a healthy indoor environment despite its tight building envelope, along with a mechanical heat recovery system to keep the heat in, even as fresh air circulates. The Zero E House relies on natural daylighting via its many windows and energy efficient, LED lighting. It was designed to work equally as well — with slight modifications — in either an urban or suburban environment.