Sandra is a Community Leader for Project Neutral in Riverdale. It is an endeavour to bring an existing urban neighbourhood to carbon neutrality. Project Neutral is campaigning to have households enter their energy use, food and transportation data in a yearly survey entry. On Saturday, November 2nd, Project Neutral, in combination with Windfall Ecology Centre, held a Home Renovation Workshop, and Sandra contributed to the Workshop by participating on a panel where she spoke about her experiences with deep housing retrofits. Here are some additional notes on the topic.
Home owners are realizing that they have been sold properties that are not performing well at all. Currently, there is currently no mandated requirement for the Energy Performance rating of the property to be disclosed at the time of the sale. A few prudent Home Inspectors are including this assessment in their inspection services.
All of the information on retrofits is based on real data and building science. The emphasis was to shift from dwelling on the type of heating system to making a sincere efforts to reduce the loads in the first place.
Air leakage is low-hanging fruit, since about 19% of heat loss is due to air leakage. Homeowners should seek the services of a professional that does blower-door-guided draft proofing where the whole house is put under slight negative pressure and you can literally feel the air leaks coming in (especially on a really cold day). When you hire a contractor to do a renovation then put the air leakage performance in the contract by specifying the leakage rate in number of air changes per hour (ACH) and have it tested after the air barrier is installed, and before the drywall is put up. Air-seal your attic floor to avoid ice dams on the roof.
However, when you seal things up then you have to think about putting in ventilation systems to get rid of the moisture: mechanical ventilation and enthalpy recovery; and exhaust ventilation where high-humidity situations occur (kitchens and baths). If you have a basement then have a dehumidifier running whenever it’s above ten degrees Celsius (as recommended by CMHC). During the winter indoor air will be too dry, unless there is a lot of moisture generated and the building is very tight. ERV’s are popular these days because they recover humidity in the exhaust air in winter and remove humidity from the incoming air in the summer if the house air is dehumidified.
Insulation is also a good place to start, with most homes and attics, not having been insulated at all. When a home is insulated properly, and tightly then it may not even need a furnace. Insulating your attic is a good place to start. The occupants and the equipment, along with passive solar heating are enough to keep the house at a comfortable temperature year-round. If you have brick exterior walls then insulate them from the outside so that there is no moisture penetration into the masonry and no freeze thaw cycle will destroy your existing brick. Better than average levels of insulation should be installed together with a vapour retarder and air barrier to protect that insulation from the humidity in the indoor air. For example, uninsulated basement walls and floors that are cool and dark become moist when they are in contact with moist humid indoor air—a perfect recipe for mould growth. Seal basement interior walls with a waterproof coating, install a drainage pan layer that drains to a weeping tile system and sump pump, and install spray foam insulation on the inside of the basement walls, in and around a lightweight freestanding stud wall that you can finish with drywall or, if financially feasible, cement board.
Windows provide heat and light which may be good sometimes, but glare and overheating is not. Ideally you want to maximize net heat gain and daylight when desired, and reject solar heat gain and control glare at other times. Passive-House-certified windows are the best available net heat gain windows. Excess solar is most effectively managed by exterior shading, including vegetation (preferably deciduous). Cheap windows also leak energy immediately and create air leaks more quickly due to the stress caused by the large amounts of thermal expansion and contraction stress, and lastly, encourage condensation on the inside of the glazing and frames that propagates mould growth. Any moist or cold surface that is subject to condensing indoor humidity is a growth location for mould.
Drain water heat recovery is copper drain pipe with a cold water pipe wrapped around it. The hot drain water goes down the walls of the drain pipe and the water supplying the shower cold water tap and hot water tank recovers the heat. The water in the water pipe is warmed and is sent to the hot water heater. Less energy is used to get it up to the temperature that is required. It is a product that is made locally in Ontario and is an investment that has very quick returns of under two years, provided that it is installed in an accessible location on a drain that services several hot water loads (dishwasher, shower, kitchen sink, as a minimum).
When you redo your roofing then consider metal roofing. You only pay for it once during the whole time that you own the house. There is currently a City of Toronto incentive for purchasing a green roof or a cool roof.
When considering a heating system then consider installing a hydronic heating system through radiators or through a modular hydronic in-floor radiant heating system. Hydronic systems use water to heat a space and water is more dense than air, thus requiring less volume to be moved, and therefore is a more efficient delivery mechanism than forced air. it also delivers heat in a more comfortable and healthy manner, with less dust and allergens. Radiant heating also has the advantage of using a variety of sources, including: electricity, natural gas; and solar. An additional advantage is that the radiant supply temperatures are closer to room temperature and this would be closer to what would be available with solar thermal supply.
Have your energy retrofit consultant do energy modelling using HOT2000 or the Passive House Planning Package software and do a Parametric Energy Model. This will help you determine the sweet spot so that you optimize the insulation levels in your building envelope.
This renovation workshop was organized by Project Neutral. Why should you do the Project Neutral survey? It is accurate for YOUR house because it knows the Ontario electricity grid mix, for example. It compares to people in YOUR neighbourhood. This year, Project Neutral is asking home owners to commit to a greenhouse gas reduction target, and will give you suggestions on how to achieve that target. For more information go to www.projectneutral.org.