Hyper-insulated homes that stand out today will be the norm in the future.
Building to performance levels that far exceed building code minimums can mean lower monthly overhead not just in the future, but from the day you move in.
Switching the focus from heat generation to heat retention.
While we look for more efficient ways to inject new heat into our homes, we often overlook the amount escaping. If the substantial investment made towards heat distribution systems is instead applied to a better building envelope, the result is a more efficient and resilient home, one that can also offer a better return on investment.
A truly high performance and energy efficient design focuses on the building envelope to ensure maximum energy efficiency. Buildings must be as airtight and as possible, extremely well-insulated, they must address thermal bridging, and whenever possible take advantage of the free heat available from the sun by designing and orienting a home for maximum solar gains.
When building to such levels, homeowners are not only rewarded with lower utility costs for operation, but greater durability, increased comfort all year round, and a security of heat in the absence of power. Our reliance on power to provide heat leaves us vulnerable to power outages; a house that stays warm much longer means you may be able to stay home when others are forced to leave due to a lack of heat.
The Passive Solar Index (PSI) is intended to recognize the efforts builders make to reduce the operational consumption of homes they build. A PSI rating can give homebuyers valuable information when shopping for homes by providing an idea of what it would cost to operate, and ultimately, its true value.
PSI concept overview
PSI is a performance index that recognizes buildings which far exceed the regional energy effiency requirements of buiding codes. Performance is determined according to PHPP software (Passive House Planning Package) established by the Passivhaus Institute.
To obtain Passivhaus certification, a building must not exceed the threshold of 15 kWh / m² annually of power consumption. PSI on the other hand, considers the fact that the Canadian climate is far more harsh than that of Germany, where Passivhaus standards originate. The PSI program recognizes buildings that consume 50 kWh / m² of conditioned space (or less) over a whole year, a performance value that would represent a 50% reduction in energy consumption over the average single-family house built to code.
The rating scale ranges from 1 to 50 kWh / m² with 0 representing a purely passive home. Ecohome engineers have evaluated building practices and determined the average construction costs required to achieve various performance levels of heating. The result shows that at the current cost of energy, in most regions of Canada it is in a homeowners best interest to double the energy performance required by code, as added building costs can be instantly negated by lower operational costs.
It should be noted that a 'net zero energy' house would not automatically equate to a PSI rating of 0, as it could have significant heating needs that are fully offset by energy production such as photovoltaic panels, for example.
A PSI rating is purely passive, factoring only heat lost through the building envelope. This offers homebuyers a very clear indication of how a particular building stacks up against another without having to consider the maintenance and replacement costs of renewable energy systems that may be present.
Cost analysis of a residential case study
Extremely high performance
at 8¢ per kWh
Source: Ecohome, feasibility study and implementation plan for a green home building on local resources, 34 pages. 2013. The price of heating costs assumes baseboards and include taxes. The cost of borrowing is assumed to be a mortgage at a rate of 3.94% for a down payment of $70,000 and a 25 year amortization. A lower interest rate or higher energy costs will have the effect of improving the economic advantage of a better insulated home. Higher mortgage rates will have the opposite effect.
Are passively heated homes worth the added cost?
In a word, yes. As seen in the table above, savings are not years away they start when your neighbour turns on the heat and you don't. With the right design for a specific climate, added costs on a building mortgage for a better performing home can be instantly negated by annual savings in utilities.
Heating represents approximately two-thirds of the average energy consumption of a house in most parts of Canada, so there are great savings to be had. When you look at building and operational costs through a 'return on investment' lens, today's standard building practices leave homeowners with higher than necessary monthly expenditures. We would all financially benefit from investing more in performance and less on injecting heat.
Who can benefit from PSI?
All Canadians and any other cold-climate homeowners. Better performing homes offer greater durability, increased thermal comfort, better air quality, better soundproofing, and reduce their reliance on an increasingly fragile power grid, as severe weather events are more frequent and more intense.
This one is easy - pretty much all buildings are eligible. PSI recognizes:
- high performing existing buildings can achieve a rating by providing a history of energy bills over at least one year;
- renovation projects which focus heavily on the building envelope;
- new construction projects with high goals for energy efficiency.
Documents required for existing projects:
- building plans;
- details of mechanical systems;
- all energy bills for a minimum of one year.
Documents required for new construction projects:
- building plans;
- wall assembly details;
- technical documentation on windows and mechanical systems;
- results of a blower door test.
Registration and information
To register or learn more about PSI and the services we offer, contact us at firstname.lastname@example.org
The Purely Passive Challenge - a house that requires no auxiliary heat
The goal of this challenge is to accomplish the feat of building a purely passive home, capable of staying at a livable temperature all year round heated only by the sun.
Is this even possible? Yes. Has it ever been done? No. Contact us if you want to be the first; we can help you make it happen. Obviously this would be climate dependent, and its feasibility increases in the southern parts of Canada. Whether or not this is a sensible decision is determined not only by the climate in which you build, but the embodied energy of the insulation you choose.
In a world weighed down by carbon emissions and a changing climate, the first builder to complete a purely passive home in a cold climate will have a nice feather to put in their cap.