If We Want to Mitigate Climate Change We Need to Focus on Legacy Building Retrofits

For environmentalists and those opposed to the continued burning of fossil fuels whether, in cars, boilers, or furnaces, our mitigation and adaptation strategies need to include addressing the legacy building challenge.

Revising and updating energy-efficiency building codes around the world addresses new construction. It doesn’t deal with old buildings and homes which are big contributors to greenhouse gas (GHG) emissions.

In Canada, there are 15 million residential buildings and approximately a half million institutional and commercial ones. Residential includes houses, condominiums and apartments. The fossil fuels burned to heat, run lighting, and the appliances in residential properties produce 18% of the country’s annual GHGs. Yet energy-efficient and net-zero code standards only address new construction which on average amounts to 150 to 200,000 new units annually.

Comparing Canada to the United States is an interesting exercise. You would think that Canadian GHG contributions as a percentage would be higher here than that of the U.S. considering our colder climate. But, in fact, as a percentage, the U.S. numbers are higher based on a 2020 study. It noted that the 93 million legacy residential buildings and homes surveyed contributed 20% to the total country’s GHG emissions annually. The study also noted that the total volume of GHG emissions from residential housing equalled Brazil’s total emissions and was greater than Germany’s totals from homes, transportation, and industry.

Finding Solutions for Legacy Buildings  Both New and Old

The U.S. adds approximately one million new residential units per year. New construction codes include energy efficiency improvements. But what is available to address the 93 million plus that are already built? The misnamed Inflation Reduction Act contains a number of programs for existing homes and commercial businesses. Some of these programs provide grants for retrofits. But probably the simplest solution is the first one listed below.

A New Coat of Paint Can Do the Trick

Who knew that a coat of paint could provide a solution to reduce GHG emissions? I have previously written about mitigating the urban heat island effect by painting rooftops white. It’s a simple idea with a big payback.

Paint containing barium sulphate, a compound used by the fossil fuel industry for fracking fluids, is the most effective way to save energy and thus reduce GHG emissions. This paint reflects 98.1% of the sunlight falling on it. An entire building painted with it would bleed heat away from the structure.

In another study done at the University of California – Berkeley, it was estimated that adopting reflective rooftop coatings (white and blue) would have a global cooling impact equivalent to removing 24 Gigatons of GHG emissions annually.

Architects know about the light and heat-reflective properties of coatings applied to buildings they design. With the right colour and paint composition a building can even reflect ultraviolet and near-infrared light. The larger the surface, the greater the savings for heating and cooling.

Surfaces in cities including streets, parking lots, and roofs provide an immediate benefit in mitigating the urban heat island effect that is commonly observed every summer.

Even paint not containing barium sulphate can be used. Most bright white paints reflect more than 80% of sunlight.

Insulation Retrofits

Insulating older homes has always been a big part of renovation projects. More than ever, now, it is a necessary investment by homeowners to help improve energy efficiency and mitigate climate change.

Insulation choices abound. Materials are rated by thermal resistance or R-value. Before proceeding to insulate an older home, an owner needs to understand which of the choices is best for his or her circumstances.

• Aerogels have been around since the 1930s. NASA uses them for spacesuits because they are light and solid. Aerogels combine polymers and solvents and then remove the fluid and replace it with air. Low in density, yet solid to the touch, it is a good insulation material choice for retrofits. Aerogel-infused fire-resistant insulation panels are available from building contractors. They reduce heat transfer through walls to retain heat or cold.
• Blown-in insulation is more readily available than aerogel-based products. The material is often fibreglass or cellulose and gets injected into walls and onto attic floors and other hard-to-reach places in an existing building. If space is missed, blown-in insulation may leave gaps that leak heat or cold depending on the season.
• Blanket or batt insulation involves removing drywall or can be cut and fitted into attic floor space. This type of insulation is usually made from fibreglass. It can be cut to fit walls before the installation of new drywall. It is often the choice of do-it-yourselfers but improperly fitted causes the same problem as blown-in insulation.

Window and Door Retrofits

In 2021 the Canadian federal government offered grants and low-interest loans to homeowners for energy audits and retrofits. The money could be used for a new furnace, a heat pump, insulation or for replacing windows and doors. The latter two contribute up to 25% of energy lost to the outside by a home or building as can be seen in a thermal image posted in a recent article on this site dealing with urban energy conservation.

Tackling old windows and doors is a good first step for homeowners to get into the climate change mitigation game. In both Canada and the United States, the governments are providing incentives to get on board.

Windows are measured using U-factors, which rate heat loss, SHGC, which calculates the rate windows block heat gain from sunlight, and finally, ER, a combination of U-factor, SHGC, and air leakage rates. Exterior shading and applied films can make windows even more efficient.

Typically, ER windows are double or triple-paned. In both types, the space between individual panes is filled with gasses like argon to reduce both the U-factor and SHGC. Triple pane windows conserve energy better than double pane but cost more. Where window upgrades fail is in installation. An improperly fitted window frame causes air and moisture leaks reducing the ER.

Doors are a forgotten contributor to home energy efficiency. It is not just the insulating properties in the door that plays a role, but also the proper framing and fitting upon installation. And finally, there is door usage. Even attached garages and their doors have to be considered.

Doors can be notorious for leaking air. Installers need to make sure the outer and inner frame, and the base provides a seal against air leaks. A feature of many Canadian and northern American homes is the use of two doors, the outer being a storm door and air and vapour barrier.

Finally, a word about how we use doors. I read a Guardian article back in 2008, where the author decried the British homeowner and retailer for their door behaviour noting they were contributing to climate change through bad habits. They were keeping doors open while running their heating. A similar experience involves air conditioning here in Canada and in much of the U.S. during summer months. Retailers are the bad actors when it comes to front doors which they often keep open to entice customers while they run the air conditioning at full blast inside.