Here’s a science-fiction proposition: What if the freely available energy falling every day as sunlight on your home could keep you warm, cook your food, run your washing machine and TV, even power the family car, and at the end of the year, your energy bill would be zero?
A NetZero home is possible. Right here in Victoria, and in a surprising number of other places as well.
I recently attended a CMHC-sponsored NetZero Energy forum in Edmonton. As it is generally defined, NetZero refers to a system of home design and construction where the home produces all the energy required for the needs and comfort of its occupants from renewable resources available at the building site. It also has an objective of good indoor air quality, resource conservation, protection of the natural environment, and affordability.
The forum was convened to review the state of knowledge about NetZero that had been developed from CMHC’s Equilibrium challenge. Participants from three Alberta projects shared their experiences- from the intial design charettes (workshops) that launched the projects throught to completion and occupation. Here are some highlights:
NetZero is possible, even in a cooler climate such as Edmonton’s. In warmer climates such as Victoria the ideas are that much easier to implement.
Achieving NetZero results from carefully following a series of steps. Common to all the presenters’ approaches were the following:
• Site assessment
• Preliminary design
• Model Energy Performance in HOT2000
• Optimize envelope
• Optimize passive solar
• Reduce Domestic Hot Water (DHW) load
• Reduce lighting and appliances loads
• Examine / Model solar DHW
• Examine / Model geothermal
• Size PV (photovoltaic system) to meet remaining total load
• Finish detailed architectural and system design
NetZero depends on an Integrated Design approach. Due to the complexity of balancing energy needs with the available renewables on the site and the right system to harness them, all the people involved in the creation of the home need to be involved from the start, communicating and brainstorming together and working out the bugs and challenges cooperatively. The team typically consists of: designer or architect, contractor, electrical and mechanical engineers, framers, tradespeople (heating plumbing, electrical, mechanical), interior designer, and suppliers of key components – particularly of the solar panel systems.
NetZero will reduce utility bills to almost nothing and can have a tremendous impact on the overall ecological footprint of a home. In all of the examples, the only expected utility bills were for the cost of being tied into the electric grid.
NetZero adds considerably to the initial cost. In the examples discussed at the forum, the incremental increase in building costs over conventional construction required to achieve NZ ranged from a low of $65,000 to $225,000. Experience across the country indicates the average costs will be in the $65,000 to $80,000 range, depending on type of systems chosen
Don’t ask about the payback. The costs for building this way are not appropriately evaluated using traditional Return on Investment criteria. As Sevag Podarian explained in his delightfully entertaining and thoughtful presentation, we don’t expect an ROI payback for a luxury car, a yacht or an executive home. The NetZero home is not a luxury item in the same way, but neither is it a commodity. The incremental costs for going from standard-built home to NetZero work out to around $4000/yr on a mortgage at 4% and 25 year amortization. This is offset by a potential saving of least $2000/yr on energy bills – a saving that can only increase as oil, natural gas and electricity costs go up in the future. You can do the right thing, be ahead of the curve, and, within 10 or even 5 years, be making money on your investment.
There is as of yet no consensus on what is the best system. Among the examples discussed were solar thermal (hot water), solar thermal (air), all-PV, geothermal, radiant heat, forced air, electric baseboards, and passive solar. However, there were key components and principles common to all the team’s experiences: Site and orient for the sun. Construct a very well-insulated and extremely air-tight envelope. Employ passive solar for baseline energy supply and then top it up with active solar collection and PV. Waste as little energy as possible.
This type of building relies on a connection to the electric grid. These NetZero homes are not “off grid”. Instead, the principle is that the home’s PV panel arrays are sized to produce a surplus of electricity in the sunny summer months that is fed into the grid. In the winter or on dark, rainy days and at night, the house draws power for its needs back from the grid in a process called net metering. In effect, the grid becomes a battery for storing energy that can be withdrawn when available solar power is inadequate. However, when the power goes down these homes will function independently at some level – providing, of course, that it’s not dark out.
Solar PV is totally central to the achieving of NetZero. Given that solar PV accounts for such a large proportion of the overall incremental costs of going NetZero and that the cost of panels are almost certainly going to come down with the development of this industry, a prudent response may be to build “NetZero Ready”. Such homes are built to implement all the energy-saving measures which so reduce the space-heating, DHW and domestic electrical demands. Their energy bills will be miniscule.
Many at the conference believe Net Zero is the way we’ll all be building in the future. Accelerating climate change and the energy price increases due to the effects of Peak Oil mean we’ll just have to. In Europe they get this. So does the provincial government; future versions of the building code incorporate increasingly stringent energy performance requirements. It’s not hard to imagine that sometime within the next decade efficient homes that produce all the power they require from the earth and sunlight will be the norm, rather than the rare birds they are today.
Leave a Reply