PEER Review – Introducing the Prefabricated Exterior Energy Retrofit Methodology
As Canada’s existing housing stock ages, more and more homes will need to be renovated – not only to update their looks and adapt to how people use their homes today, but for increased energy efficiency. Our country has 14 million residences, and approximately half of that stock was built before 1985. Given that a home built to code today is 47% more efficient than one from 1985, if Canadians truly want to address climate change within the housing sector, we’re going to have to get innovative.
CHBA and its leading members have been working hard to pursue energy efficiency innovations for voluntary adoption, staying ahead of the curve while advocating that regulation wait until next levels don’t reduce affordability, both for new homebuyers and Canadians who already own a home. When possible, CHBA works with government to find solutions and offer industry assistance for research and development.
One promising approach that is currently being explored is using modular construction technology in renovations. The Prefabricated Exterior Energy Retrofit (PEER) methodology is being championed by Natural Resources Canada (NRCan) and was recently presented during a meeting of CHBA’s Canadian Renovators Council.
Using PEER technology in renovations
Applying the PEER technology involves four key steps:
- The building is accurately measured.
- Large exterior, airtight, super-insulated cladding panels are designed.
- The panels are manufactured offsite.
- The panels are delivered to the site and installed.
Utilizing PEER methodology will bring Canadian-manufactured housing companies together with renovators to create a market for prefabricated, energy efficient façades which can be retrofitted onto existing buildings.
The pictures (on the facing page) illustrate the potential of the process on a simple construction trailer which NRCan presented as a PEER “Proof of Concept” pilot. This gave the researchers a first-hand opportunity to study the construction retrofit process, assess the opportunities for energy performance potential, and determine the practical implications for construction.
This approach to renovation has several advantages:
- Speed. Once the industry has experience, PEER has the potential to significantly reduce the time it takes to renovate homes and buildings to an improved level of energy performance.
- Enhanced Performance. The PEER panels can be designed to add significant levels of insulation and improve the overall airtightness of a building. This improves occupant comfort, reduces utility costs, and protects the owner from future escalation of energy fuel costs.
- Occupant Convenience. Since the renovation is completed largely from the outside, disruption to occupants is minimized. In many cases the occupants are not displaced by the renovation work.
- Improved Curb Appeal. The renovation provides a complete facelift for the building. With appropriate material selection, the exterior will remain beautiful and maintenance-free for years.
- No Loss of Floor Area. Many of Canada’s older homes have limited floor space. Occupants will appreciate the fact that the renovation is exterior and does not affect the useable interior floor space.
A Brief Overview of the Process
Measuring the Building
All seasoned renovators understand the importance of accurate measuring. So how close do the measurements need to be? For the position of windows, the window openings (height and width), and the overall building width, each has to be within ¼” (6 mm). Building height from the top of the foundation to the soffit, the average grade to the top of the foundation, and the centerline of building penetrations (including utility meters and service entrances) need to be within 1″ (25 mm).
The options for taking the measurements include:
- Measuring by hand – This is the lowest cost, but least accurate.
- Total Station Theodolite – While many of us have never employed this technology, equipment and operators are widely available. It is extremely accurate but does not capture as many points and as much detail as laser scanning. The data is easily imported into CAD drawings.
- 3D Laser Scanning – This produces detailed datasets but they may be so large they are hard to work with. This approach has a high degree of accuracy. Special software is required to use the data. The scanner has difficulty capturing data from very dark or reflective surfaces.
- 3D Photogrammetry – This technology uses a high-resolution camera to take pictures of the building, then uses software to calculate the measurements. The accuracy is lower than the theodolite and the laser. This technology is commonly used today for estimating roofing projects using aerial photos taken from planes or drones.
Designing the Panels
The panels include a “squishy” layer for plumbing the panel where it meets the existing building. Panels need to address the insulation requirements as well as airtightness.
PEER Panel Manufacturing
Panels can be constructed up to 24′ (7.4 m) in length. Ideally, panels will be manufactured offsite in a climate-controlled facility.
PEER Panel Delivery and Installation
Completed panels are transported to the site where they are moved into position with a crane. The panel’s weight is supported on brackets attached to the foundation. The panel is then secured to the framing of the existing walls. Panels are supplied as completed insulated wall assemblies including claddings, with windows and doors installed. The old windows and doors in the existing building wall will be removed prior to the PEER panel being installed.
The Butterwick Group, a CHBA member company based in Edmonton, is leading a 59-unit pilot project using wood-framed PEER panels to achieve Net Zero Ready. Ottawa Community Housing will also undertake a pilot to retrofit four townhomes to Net Zero Energy using structural insulated panels (SIP) in 2020.
The Time is Right
To address climate change, future renovations will need to involve deep energy retrofits. CHBA members get a leading advantage on new technologies and ways of doing business. And the Association advocates for factors that will hopefully contribute to homeowners’ interest in renovating for energy efficiency, including home renovation tax credits. With the help of government research and development, methodologies like PEER should allow projects to be completed faster, allowing renovators to help more Canadians each year improve their home’s efficiency. It can also help renovators take on larger residential projects that they might otherwise not consider, since PEER is equally applicable to large homes and buildings. All in all, the future looks bright (and energy efficient) for Canadian renovators.
|Mark Carver is a Project Leader with the Housing Team at CanmetENERGY, Natural Resources Canada.|
|Gary Sharp is the Director of Renovator Services at CHBA.|