Heat Pump Chronicles Vol 5

This is the fifth in a series of posts on our journey to navigate government grants and loans available for home energy retrofits and to replace our natural gas furnace with a cold-climate heat pump. Click here to see all articles in the series.

My wife Dayle and I have been living with our Mitsubishi Zuba cold-climate heat pump for over three months now and are still very pleased with its performance. We survived last week, through several of the winter’s coldest days, minus 16 degrees Celsius at night, minus 22 with wind-chill.

Overall our house has been more comfortable, mostly because the air isn’t as dry as was the case with our previous natural gas furnace. Scientifically, I’m not sure why that is the case. We are still heating the air and adding water through the same humidifier. But during last year’s cold snap, our humidity dropped to about 30%, whereas this year it’s been hovering around 50%. That means no static cling and no painful shock as you touch a light switch. The absence of these things is noticeable. It also means that we’ve been able to lower the thermostat temperature by a full degree without loss of comfort.

Not that the entire experience since installation has been perfect. There are a few things about the process that you should be aware of should you decide to embark on a similar project. I want to start with the energy audit process for that is key to accessing government grants and loans.

Two audits are required. The first is performed before any changes are made. This “pre” audit establishes an energy efficiency baseline and provides the homeowner with recommendations as to which energy investments will have the biggest impact.

The second, or “post” audit is done after all work is complete. This audit evaluates the changes in home energy efficiency that can be directly attributed to the enhancements that were made. This audit is used to prove that the work was done so the government can pay the grant and or provide the loan.

Hiring an energy auditor can be a daunting process. They speak a strange dialect, using words like, ASHRAE standards, air exchanges per hour, Heating Seasonal Performance Factor and, Seasonal Energy Efficiency Ratio. Perhaps I’ll explain these terms, at some point, in a separate article entitled, “Boring Details One Should Know Before Buying a Heat Pump”!

Anyway, once past the technical jargon, the auditor is just like the rest of us who put our pants on one leg at a time. Ask plenty of questions until you understand what they mean. And don’t get me wrong; about 11% of energy auditors are women. It’s just that pants are recommended. Male or female, they are required to go into attics and crawl spaces in performing their work. Our energy auditor spent almost four hours assessing the home exterior as well as every room and space inside the house.

The basic premise of an energy audit is to measure energy efficiency, the less required to do the job, the better. For instance, an Energy Star rated LED light bulb uses about 1/10 of the electricity of a standard incandescent bulb while providing the same amount of illumination. Efficiencies of appliances and computers can also vary considerably. New appliances tend to be more energy efficient. It’s important to read the label and choose a product with the lowest energy rating while still having all the features you need.

For a home, energy efficiency is all about the thermal resistance of the building envelope. A building envelope includes all building components that separate the indoors from the outdoors. Walls, floor, roof, windows, and doors are all components of the building envelope.

Thermal resistance is a measurement of a material’s or a component’s resistance to heat flow. The thermal resistance of a material or component is is often called its R-value. The higher the R-value the greater its thermal resistance and the greater its ability to keep heat inside the house. Windows and doors typically have a lower R-value than insulated walls. And, because heat rises, high R-value attic insulation is really important to slow down that heat from escaping through the roof. Actually, to be technically accurate, windows use U-value to measure energy efficiency where a lower rather than higher number is better. Think of U as just an R heading in the opposite direction. Clear? Didn’t think so.

Anyway, the point is, energy efficiency of a building envelope decreases with the number and size of openings. We think of openings as being windows and doors and that’s true. But even when doors and windows are closed tight, there are plenty of places where air, (and heat), can escape. The biggest culprits are often invisible cracks around window and door frames, gaps in walls around electrical outlets and under baseboards, or leaks around fireplace chimneys, basement foundations and where plumbing or electrical connections are made through the building’s exterior. These unintentional sources of home ventilation can amount to huge energy efficiency and financial loss.

An effective way to find these nearly invisible sources of heat loss is by having an energy professional complete a “blower door test”. This test is part of every pre and post energy audit. To perform the test, the energy auditor opens the front door and installs a large fan surrounded by a canvas like material in an adjustable frame. The frame is quickly adapted to fit the door and the material effectively seals the opening except for the fan.

When the fan is switched on, it sucks air out of the house. The fan is calibrated. It measures the amount of airflow going out of the house to maintain a certain constant pressure difference. Of course, whatever air is going out must be being replaced by air coming in, much like trying to fill a bathtub with the drain plug pulled.

With the fan running and walking from room to room, it’s pretty obvious to “feel” where the unintentional openings are. A tube of caulking and a can of spray foam, along with a steady hand, a screw driver and copious amounts of time, are all that’s usually required to fill most of the gaps. Leakage of the doors and windows themselves can be mitigated by installing weatherstripping. Note, it’s important to caulk the edges of installed weatherstripping for it to be an effective seal.

Any time a professional spends four hours with you, expect to pay big bucks. Our pre-audit cost more than $500. The post audit was just under $300 but the post audit was done in less than 1/2 the time.

Energy Audit before upgrades
Energy Audit Pre Upgrades
Energy Audit post upgrade
Energy Audit Post Upgrades

So what were our results? The pre-audit showed that 63% of our energy use was in space heating and 16% was for hot water. It showed that 25% of our home heat energy was lost through air leakage in the building envelope. This was despite the hours of work I’d put in years ago to install weatherstripping and fill up cracks and crevices!

The auditor’s report recommended we upgrade our heat and hot water systems, do more to seal up the building envelope and add a renewable energy source such as solar roof panels.

Fortunately the structural integrity of our windows and doors was intact so we didn’t need to replace them again. And thank goodness no major leaks showed from under the baseboards where I had sealed before. That was a task and a half, on my hands and knees, running a continuous bead of caulking around the entire house perimeter. I didn’t want to have to do that again!

We did have leaks we hadn’t noticed the last time. Leaks were evident where plumbing fixtures drained through holes on the inside of exterior walls, around our basement fireplace, where weatherstripping was cut around door security contacts, where the weatherstripping was not sealed and where it had deteriorated from use. Fortunately these deficiencies were easily rectified. I installed new weatherstripping, this time putting it under the security contacts and sealing it carefully with caulking both inside and out. I used foam to fill the larger holes around pipes and the fireplace surround. And daps of caulking filled the smaller holes and cracks.

We replaced our natural gas furnace with a fully electric heat pump. While it has worked well so far, we’ve now maxed out our existing electric service panel and are facing massive upgrade challenges that I will save for another post. So adding an all electric hot water tank was out of the question, as was the installation of a hot water heat pump. That technology is too expensive at the moment, no matter how much we want to save the planet. We are still considering adding rooftop solar but we can’t begin to think about that until our grid connection issues are resolved.

Speaking of saving the planet, our energy upgrades have resulted in a 60% reduction in our carbon emissions from 6.5 to 2.6 tonnes/year. As for energy use, the report estimates we will see a 14% reduction from 155 to 134 gigajoules per year. That, however, may or may not translate into financial savings because of the incredibly cheap price of natural gas compared to electricity and the uncertainly surrounding the future of the escalating price of carbon. In a future post I will give you all the reasons why the carbon tax is good for Canadians. In the meantime, based on two months worth of bills, it looks like the savings we are seeing on our Enbridge gas bill vs the additional electricity cost through Alectra effectively comes out as a wash. Now if I can just get Enbridge to send me the grant cheque!

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