Finding the Right Property
Converting an existing property into an off-grid, solar-cogen-powered building is a big project, and we knew the costs could add up quickly if we weren’t careful. To save time and money, we looked for a property that would allow us to make the necessary changes as smoothly as possible.
The following factors were top priorities for us when choosing the site:
- The amount of material from the original building that we could keep for use in the new design. We knew that finding a building with a usable foundation would allow us to bypass the time and money required to completely demolish a property and put up a new one from scratch.
- The ease with which we could improve the energy efficiency of anything we kept from the original structure. It was critical that we seal up any leaks in the old foundation as efficiently as possible, so that we could ensure long-term energy savings without incurring major front-end expenses.
- The location of the building within the city itself. We eventually chose a site located in Bonnie Doon, which is in walking or biking distance for all of the office staff. Putting our office in the downtown core encourages our employees to bike to the office instead of commuting, further reducing our company’s environmental footprint.
The most important part of designing the building was to take Edmonton’s climate and environment into account. The city receives bright sunshine on approximately 325 days per year, but this is offset by our notoriously cold winters with relatively early sunsets. That being the case, it was vital for us to incorporate a lot of redundancy in the system — giving us access to the power we need, even during particularly bleak stretches of weather.
We settled on a design with three major features intended to work in concert with each other:
- Solar panels: a 4.8 kilowatt solar panel array generates most of the electricity needed for the building, especially on sunny days.
- Batteries: six 1000-watt lithium ion batteries collect extra energy from the solar system, and store it for future use.
- mCHP units: two of these innovative appliances, called micro Combined Heat Power (mCHP) units use natural gas to produce electricity and heat on-site during times when there is not sufficient sunlight or energy stored in the batteries to meet the building’s needs.
The idea behind having all three of these systems in place was to provide contingencies. On a day with weak sunlight, for example, the solar panels collect what energy they can from the environment and store it in the batteries. The mCHP units are then activated to add supplemental energy to the batteries as needed, and the office draws its electricity from the batteries themselves. Conversely, on the days when the batteries are full and the sun is bright, an electric resistance heating element built into the water heater allows any excess solar energy to raise the temperature in the building and heat tap water.
Significant changes needed to be made to the original building before the new, self-contained electrical system would be efficient. We removed almost everything from the original structure, but kept the foundation and exterior walls because it gave us a base upon which to build. Keeping these original features and making a few necessary adjustments to them was also less expensive than it would have been to demolish and rebuild the property completely.
After stripping the building down to its structural elements, we focused on several key areas for improvement. One of our first moves was to install energy efficient Innotech triple-glazed windows, which can save 2-3% more on a building’s heating bill than double-glazed options. That might not sound like much, but it adds up over time. Triple-glazing also keeps more humidity indoors during cold weather, which provides extra comfort to the office’s occupants.
We also implemented the HP+ wall system assembly, which addresses insulation, moisture control and durability issues while providing air tightness to prevent cool outdoor air from leaking into the building. Adding spray foam to the exterior of the existing foundation and combining it with EPS foam insulation on the inside created a tight seal, completely transforming the leaky old foundation of the original site into a brand new building envelope with an R-value of over 40.
Using Natural Gas to Leave the Electrical Grid
The combination of solar panels and mCHP units that fill the office’s batteries with usable energy allows it to be completely disconnected from the city’s electrical grid. The mCHP units, however, are powered by natural gas — meaning that the property still needs to be hooked up to Edmonton’s natural gas grid. Still, eliminating the need for just one grid allows a property owner to avoid all the administration, transmission, and distribution charges that go along with using it. Here’s how using a little natural gas allowed our office to leave the electrical grid completely:
- The CoGen system’s twin mCHP units run on natural gas to produce heat and electricity right on site.
- Heat generation is the primary function of these appliances, but in this case electricity is generated at the same time.
- The thermal energy produced when the units generate electricity is harnessed and used to heat the building’s water, which fan coils use to spread heat throughout the space as part of a forced air system. The heat is also used for domestic hot water, which flows to the water taps. The electricity flows to the batteries, where the energy is used for the building’s needs.
- When the sun is shining, the electricity produced by the solar array flows to the battery bank, providing a sustainable (and free) source of energy.
- Because the electrical grid in Alberta is powered by fossil-fueled generating stations, we can reduce greenhouse gas emissions with a more efficient site-based generator that produces electricity at the same time as efficient hot water heating.
Check Out the New Office!
The grand opening of our new office saw hundreds of excited visitors come to check out the space, including Mike Holmes and Mayor Don Iveson. In the relatively short time since then, we’ve received a great deal of praise for creating Alberta’s first electrical-grid-free office — SAIT is even running a one-year study on the system we designed, and releasing the results to encourage future advancements in the field.
With all the excitement, it was only natural to have a little confusion as well. When we called the electrical grid supplier and asked them to disconnect the building, they couldn’t understand how we were going to keep the lights working. Even the technician they sent over was reluctant to cut the wire, until we told him we generated our own electrical power on-site.
Our first winter in the new office brought with it the coldest February in over four decades, but the system performed admirably. Now, we invite you to come see this revolutionary new project for yourselves — as proof that it’s possible to build energy-efficient commercial spaces that reduce carbon emissions and improve neighbourhoods, even in challenging environments.
Interested in learning more, Taking Your Home Off-Grid is a good read.