Building Energy Savings 101:

Operational savings are but one part of understanding the dynamics of looking at your home as a “whole house” system, as opposed to individual aspects that, without considering the home, can and do cause other issues. In the fall of the year, I often get e-mails that ask: “My new windows are covered in condensation.”  

 It’s not the windows’ fault I tell them, you have changed the ability of the house to breathe, and your new windows are exposing this condition. Some form of ventilation should have been considered, since the windows and all the other energy upgrades that have likely been completed in this home now affect the interior air exchange of the home. The house as a system was ignored. An average Canadian home produces upwards of 50L of moisture a day, depending upon occupancy. This is generated by cooking, showers, washing dishes and other normal activities. If the home does not breathe then condensation is the visible condition. The invisible ones often show up as mold.

There are three aspects to a “house system.” They are: 1) building air quality and heating and cooling; 2) mechanical systems and this aspect should include appliances and electronics and 3) safety and health in the home. Occupant behaviour and moisture control by those occupants, as well as where you live affects the level of energy efficiency and, therefore, the big benefit every homeowner is looking for, operational cost savings.

The first step is getting an energy audit done by a certified EnergyStar auditor. He or she will provide you with a benchmark, suggestions as to improvements and then they will come back and confirm what you have attained with your sweat labour and bank account.

Step two is reducing the amount of conditioned air leaving your home. While I give caulking a bit of rap at times, it is part of the improvement all be it a small part. For a proper air sealing effort you will need foil tape, tuck-tape, spray foam, backer rod, foam seal tape, weather-stripping, mastic sealant, foam wall plug inserts for exterior wall plugs/switches along with caulking. Insulation upgrades will be required as well since insulation helps slow down the exchange of air; this is the real meaning of air sealing. Upgrading attic insulation should be first on that list, then your basement, with occupied levels last.

Step three is rarely done, but leaking ductwork is a major energy loss. Most homes have a forced air heating and cooling system. Upwards of 25% of the efficiency of your HVAC system is lost in uncontrolled air circulation of your system. This is where the foil tape and mastic sealant is used. Air sealing is not just outside the home, it has value in specific areas inside as well.

Step four is ventilation and, next to duct sealing, it’s the most commonly misunderstood condition in a home and usually forgotten until it exposes itself, often with costly results. Efficient air exchange is best achieved through controlled ventilation. A drafty home is neither healthy nor efficient with respect to ventilation. Air exchange cannot be controlled and is strongest when the air temperature differential is the greatest. Using winter as an example where its -20C outside and your interior temperature is +20C, your home is expected to handle a 40C temperature differential. Cold drafts are acute. They make a room feel colder than it is and puts a strain on an HVAC system. During the late spring and early fall you will get little or no air exchange, yet your home is still producing moisture.

If you cannot install an HRV then properly installed fans with external discharge is the next best plan. You can buy humidistats to control excess condensation; start in your bathroom. Timers can be retrofitted to a good fan and work well; both are reasonable in cost. Install external fans with a low “sones” rating, along with an energy star ranking.

Once you have completed these four steps, step five will give you the real energy audit numbers to evaluate what size of furnace and air conditioner you should consider. At minimum, a 90% efficient furnace should be in every home and if you can afford one with an ECM motor and multiple speeds or a full modulating furnace, your operational costs will decrease a bit again. The growth of heat pump systems, also called mini-split systems should also be given a close look if you are contemplating an upgrade.

Lighting is well known to have a direct impact on energy costs. This sixth and final step has either a reasonable cost or it can be pricey, depending on what you can afford. A conventional 60 watt bulb replaced with a CFL reduces direct energy use by 78%. One factor often overlooked is the wasted heat that the old bulbs produced. If you can afford LED lighting, your costs will fall a bit more; since you’re lighting’s lifetime will increase fivefold with some LED lighting.