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Affordable Energy Efficiency

Affordable Energy Efficiency

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Affordable Energy Efficiency

Images courtesy of Butterwick Construction & Carpentry Ltd.

Newly built Canadian homes have been steadily increasing in energy efficiency over the years – a code-built home today is 47% more efficient than one from 1985. Still, the Canadian Home Builders’ Association (CHBA) and its members are hard at work pursuing still greater energy efficiency innovations for voluntary adoption, while at the same time advocating that regulation wait until next levels don’t reduce affordability. But to truly address climate change in the housing sector, it is the existing housing stock that needs to be upgraded. Enter CHBA and its leading members again, as the pursuit of innovation for affordable deep energy retrofits working all the way towards net zero renovations kicks into gear.

Increasing Energy Efficiency in New and Older Homes

In new housing, industry leaders are paving the way to greater energy efficiency through voluntary programs such as the CHBA Net Zero Home Labelling Program. Founded by CHBA’s Net Zero Energy Housing Council, which is now five years old, CHBA’s leading members are providing discerning homeowners with net zero and net zero ready homes today, while working to innovate for greater affordability and increasing market penetration with each year.

But improving new homes alone won’t achieve the national goal, and it won’t help the millions of Canadians who live in older homes and want improved energy efficiency. Canada has 14 million residential residences, and approximately half of the current housing stock was built before 1985. Many of these older buildings are far behind new homes when it comes to energy efficiency. Even if all the new homes built from now until 2030 (say 200,000 per year, or 2 million total) were built to zero emissions, we still wouldn’t hit our environmental target – not even close.

Why Retrofits Are the Future

Renovating the existing housing stock is the only way for Canada to reach its greenhouse gases target in the housing industry. And with the half of our housing consuming twice as much energy as everything built since, that’s a lot of opportunity for renovators.

Canadians want their homes to be energy efficient. Maybe it’s a sense of social responsibility, uncertainty around utilities, simply a desire to reduce increasing energy bills, or a bit of each, but today’s homeowners are looking for improved energy performance. In fact, according to CHBA’s Home Buyer Preference Survey, powered by Avid Ratings Canada, nearly 90% of recent homebuyers indicated that having an energy efficient home was important to them. The survey gathers opinions of thousands of recent new homebuyers each year, and their preferences can easily be applied to renovations as well.

As Canadians seek higher levels of performance and comfort, the industry continues to innovate to strive to meet those desires in the most cost-effective fashion. And that innovation is needed to begin retrofitting older homes, which come with their own unique challenges.

Older renovated homes like this extremely efficient retrofit by Butterwick Construction & Carpentry Ltd. in Edmonton, Alta., are voluntarily paving the way to Net Zero renovations.

Setting the Stage

Drastically improving the energy efficiency of an older home requires an in-depth technical understanding of building science. And the best examples we have of that are by looking at Net Zero Homes.

A Net Zero Energy (NZE) home is one that produces the same amount of energy it uses, on an annualized basis. These homes are extremely well-built: they have very airtight, well insulated building envelopes with high-performance windows and doors. They also use efficient, right-sized mechanical systems in order to reach higher levels of energy performance. In addition to being incredibly efficient, NZE homes have built-in renewable energy generation (mostly solar panels). In some cases, they incorporate energy storage systems which allow homeowners to bank energy for future use. A Net Zero Energy Ready home (NZEr) is built to the same level of performance, but installation of the renewable energy component is left to the occupant at a future date – a popular option among NZE builders and homebuyers.

In both cases, the result is a home that delivers unrivaled levels of occupant comfort, minimum environmental impacts, and utility bills with much lower energy consumption.

CHBA is leading efforts to bring NZE and NZEr homes to market as affordably as possible. As the industry voluntarily learns new efficiencies with the technology and building practices involved, building costs are decreasing. CHBA’s aim is to share efficiencies and innovation among industry-leading CHBA members so that eventually the cost of owning a NZEr home is comparable to one built to conventional standards.

The first step was a demonstration program in 2015, backed by Owens Corning Canada and the federal government, that saw the construction of 26 such homes across Canada by five leading residential builders. Based on this success, CHBA launched its Net Zero Home Labelling Program to ensure that each participating home is qualified by a third party to meet the specified technical requirements. The program also includes training requirements for participating builder members and energy advisors.

And now, that scope involves renovations.

Bringing Net Zero Solutions to Renovations

The move to bring NZE homes and renovations to the marketplace is being spearheaded by the residential construction industry itself, through the work of CHBA’s Net Zero Energy Housing Council.

A broad collaboration involving homebuilders, manufacturers, utilities, design experts, government agencies, and service providers, the Council’s primary focus is on how to support innovation in the industry with the goal of creating a market advantage for CHBA builder and renovator members voluntarily pursuing Net Zero Energy.

Currently, they’re working to extend the Net Zero Program to renovations, so that older homes that meet the program requirements can receive the Net Zero/Ready label. To date, more than 100 new homes in Canada have received the label, which includes third-party verification. The program is growing exponentially each year as demand grows for not only energy efficiency at an affordable price point, but the comfort and health benefits that come with NZE homes.

Learn more about the CHBA’s Net Zero Home Labelling Program at CHBA.ca/nze and NetZeroHome.com.

Sonja Winkelmann, CHBA’s Director, Net Zero Energy Housing


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CHBA Connects - Book Smarts

Book smarts – An exclusive sneak peek inside the CHBA’s new renovators’ manual – Apr/May2019

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Book smarts – An exclusive sneak peek inside the CHBA’s new renovators’ manual – Apr/May2019

As you know from previous columns, CHBA has a Renovators’ Manual in the works. Similar to CHBA’s best-selling Builders’ Manual, the Renovators’ version applies building science to renovations. Existing buildings are going to be important as Canada takes steps to limit climate change. This month we offer a small sample of what readers can expect from the new book, when it is released to the public.

Canada has more than 14 million existing houses. Over half of these were built before 1980. That’s important because these older homes were not built to be anywhere near as energy efficient as houses being constructed today. In fact, a house built today is 47% better in terms of energy efficiency than a house built in 1985.

Building Codes are addressing the energy efficiency of new houses. Current plans are for new houses to reach Net Zero Ready levels of energy efficiency by about 2030. Currently, builders are constructing approximately 200,000 housing units per year. This number has been quite consistent in recent years, although it is expected to slowly drop in the face of an aging population. Some simple math shows us that over the next 10 years, building at the anticipated rate, we can expect between 1.8 and 2 million more houses to be created. While these will be far more efficient than the houses we have now, there is no scenario for reducing the total amount of energy used by homes without addressing the existing housing stock.

The Renovators’ Manual will help with those renovations as renovators are asked to significantly improve the energy efficiency of existing houses. Looking a little deeper, this means that renovators will be asked to “apply” the building science they know to existing houses. This is not as easy as it might seem, since applying building science to the materials and systems that are already installed is quite different than starting with a clean slate when designing a new build. The process also involves combining new materials with the existing structure they are renovating.

Net Zero Ready houses are typically being constructed with R-65 ceilings, R-40 walls, triple-glazed windows, R-35 basement walls, and R-10 under the basement floor slab. They will also have air tightness of less than 1.0 air change per hour at 50 Pa of depressurization (ACH50). Even the most ambitious renovation of an older home would find these performance characteristics difficult to match, but renovators will want to know how close they can come, and how to avoid technical problems in doing so.

The challenge will come from the correct “application” of the building science. The houses that need the most work are expected to be the older ones. Many of these have little to no insulation. Even if these houses have been renovated previously, it is unlikely that the renovation will have added a significant amount of insulation. It will be useful to review the most likely starting condition of the house, for example;

  • 2×4 wood frame or masonry structural exterior walls
  • Little or no insulation in the walls
  • Little insulation in the ceiling
  • Little or no insulation on basement walls or under the basement floor
  • Poor airtightness characteristics (i.e. drafty)
  • Large humidity swings – low in winter and high in summer
  • Large furnace and/or air conditioner
  • No heat recovery ventilator – bathroom fans or windows for ventilation
  • May have a wood-burning fireplace
  • Poor drainage around foundation
  • Double-glazed windows

Other important considerations are the climate where the house is located, and the characteristics of the occupants of the house. A maritime climate has different characteristics than a prairie climate. A house with two seniors has different operational characteristics than a house with young children. As renovators, we can’t change the occupants, so we need to provide a home that suits their specific lifestyle and needs.

In the case of the house described above, lets look at what has been happening over the years since it was built.

  • The house has had little insulation so large amounts of energy has been flowing though the building envelope.
  • The house has numerous holes and air leaks that result in large heat losses, however the benefit of such high air exchange rate is better, if uncontrolled, indoor air quality. If there is a wood-burning fireplace, these typically allow large amounts of house air to exhaust through the open chimney. Even with “tight-fitting doors or flue dampers, the fireplace chimney is generally a huge energy (and air) loss source for the building.
  • Relative humidity in the house is expected to have been low in the winter, due to the high air exchange rate and high in the summer, for the same reason. This would lead to the house being hard to heat and cool, but also uncomfortable.
  • Windows, in particular in the “wet” rooms such as the bathrooms and the kitchen, were likely subject to condensation on the glass in the winter and the shoulder seasons.

When looking at such a typical existing house the first step is to examine the decisions that need to be made. In this case, let’s pick a traditional war-time, Victory Home which are common in many cities across the country.

Blown opportunity: most older homes have little to no insulation in the wall cavities, an obvious first step to improving energy efficiency.
Blown opportunity: most older homes have little to no insulation in the wall cavities, an obvious first step to improving energy efficiency.

General

The renovator will need to decide on the building science features which need to be addressed.

  • If the drainage is poor, this needs to be fixed, regardless of what the house is made of.
  • The basement floor is uninsulated. This will not be a comfortable floor without insulation. It is unlikely that removing the basement floor, adding insulation, and then re-installing a concrete floor makes sense unless the existing floor is in poor condition. Therefore, insulation can only be added to the top of the floor. This will be limited by the basement ceiling height.
  • New triple-glazed windows will be needed to improve the envelope.
  • The wall thickness will need to be increased to accommodate the increased insulation.
  • The key building science features needed:
    • Weather barrier
    • Rain screen
    • Thermal barrier
    • Air barrier
    • Vapour barrier
Historic victory: across the country, many WWII-era victory homes, originally built as temporary housing for industrial workers, are still standing as permanent but inefficient homes.
Historic victory: across the country, many WWII-era victory homes, originally built as temporary housing for industrial workers, are still standing as permanent but inefficient homes.

Victory Home

This house will be wood-frame. It is unlikely that the exterior of the house is historically significant, and therefore the renovator has options. The insulation can be added to the interior or the exterior of the building. While working on the inside of the home is easier, the Victory Home is a modest size and the owners may be reluctant to reduce their floor area. To accommodate this, the decision may be made to add thickness to the exterior. The method of increasing the thickness of the wall studs will be the most problematic decision. This can be done in a number of ways and an architect should be consulted for a suitable solution. Typically, the frame of the existing house is structurally sufficient enough to allow the extensions to be “hung” from the existing walls. If that decision is made, then several items fall into place.

The weather barrier is the exterior cladding. Unless an air space is incorporated into the cladding by the nature of the cladding itself, it needs to be installed on strapping to provide an air space.

The rain screen is the air space between the cladding and the house wrap or the insulation installed over top of the studs.

The thermal barrier could be selected to do “double-duty” by selecting foam insulation which also has air barrier properties.

The selection of the vapour barrier is required. Keep in mind that vapour diffusion is a relatively weak process for moving moisture and is dependent on the surface area covered. If 90% of the surface is covered, then 90% of the vapour diffusion is prevented. Moving air is the primary transport mechanism for moving moisture. If the air barrier feature is being handled by another material, the vapour barrier can be a vapour retardant paint (if the interior drywall was not removed, the vapour barrier may already be in place with the existing, multiple coats of paint). If the walls were opened, there is an opportunity to install a sheet-type vapour barrier. This can be polyethylene, or it can be one of the materials where the vapour permeance changes with humidity. This will allow any moisture which happens to get into the wall due to poor flashing details or poor window installation to dry.

The ceiling can be sealed by removing the existing ceiling insulation and applying two or three inches of spray foam insulation to provide the air barrier properties. The desired amount of insulation can then be blown in on top of this to provide the thermal barrier function.

The basement walls and rim joist space decisions will generally be based on the type of foundation present. The most likely options are concrete block or poured concrete. Poured concrete is considered an air barrier, while concrete block is not. If poured concrete, spray foam insulation may be the best solution for connecting the air barrier in the walls, the rim joists, and the basement wall. If concrete block was used, an alternative such as airtight drywall, a vapour permeable, air barrier sheet material or spray foam insulation against the concrete block wall. Typically, drainage is poor in these older houses so a mechanism to allow these walls to dry to the inside is preferred. A provision must be made to ensure that the air barrier is connected to the concrete floor as well. How to do this detail will depend on the method chosen to provide the air barrier for the basement wall.

Now, with the house better insulated, with better windows and more airtight, the air conditioning and heating systems will be over-sized. If left as-is, oversizing will lead to short cycling and this may lead to inadequate distribution of heat and cooling in the house. Also be aware that with the improved air tightness, mechanical ventilation will be required to eliminate cooking odours and to control humidity levels. Therefore, the renovation should include an upgrade to the heating and cooling equipment as well as adding a heat recovery ventilator.

Hopefully this example highlights some of the challenges that renovators might expect and demonstrates the role the new CHBA Renovators’ Manual will play in helping renovators with the decisions they will be making to improve the energy efficiency of housing across the country.

Gary Sharp, CHBA

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