A building’s roof is one of its most important defences against environmental heat. Yet decisions about existing roofing are most often approached simply as maintenance issues—the roof has deteriorated to the point that it must be repaired or replaced.
CoolRoofsBC recommends viewing this situation much differently, with every roofing project considered as an opportunity to evaluate cool roof options and provide additional long-lasting benefits for the building itself and the larger community in which it is situated.
Introduction
A building’s roof is one of its most important defences against environmental heat. Yet decisions about existing roofing are most often approached simply as maintenance issues—the roof has deteriorated to the point that it must be repaired or replaced.
CoolRoofsBC recommends viewing this situation much differently, with every roofing project considered as an opportunity to evaluate cool roof options and provide additional long-lasting benefits for the building itself and the larger community in which it is situated.
Every roofing project should more broadly consider three important questions:
Can the service life of the existing roof be extended?
If replacement is necessary, what should it be replaced with?
Can the roof also support solar-energy production?
These questions are becoming increasingly important as British Columbia experiences hotter summers, more frequent extreme-heat events and a growing need to sustainably generate more electricity. Increasing local electricity production could also contribute to greater energy resilience, particularly in BC’s seismically vulnerable South Coast region. Rooftop solar presents one opportunity to do so.
Roofing decisions made today will remain with a building for decades. As such, the objective should be not simply to address today’s roofing problem, but to make roofs better able to reduce heat, conserve resources, support local renewable-energy production and passively provide these benefits well into the future.
This is the thinking behind Extend-Replace-Power Up.
EXTEND — Can the Service Life of an Existing Roof Be Extended?
Particularly for commercial, institutional, industrial and multi-unit residential buildings, an aging low-slope roof does not necessarily require replacement simply because it has reached a particular age, shows signs of deterioration or has begun leaking. Where its condition remains suitable, restoration using a high-performance roof-coating system can provide a cost-effective way to extend the roof’s service life—with further extensions potentially possible through successive “top-up” coating cycles.
Reflectively coating a suitable existing low-slope roof can provide benefits beyond extending its service life, generally at lower cost than replacement. Dark-coloured low-slope roofing traditionally installed in British Columbia absorbs a substantial proportion of the solar energy striking it, increasing heat transfer into the building and thereby increasing cooling demand and energy costs.
A high-performance white reflective roof coating significantly reduces this solar heat gain. Depending on the building, climate, insulation levels and existing roof condition, studies have estimated cooling-energy savings of approximately 15%, with some reporting much greater savings. A reflective coating’s thermal-emittance properties—its ability to release absorbed heat—can also help keep buildings cooler during overnight hours.
When Is a Reflective Roof Coating Appropriate?
Restoration using a reflective roof coating is not an appropriate solution for every roof. Trapped moisture, extensive deterioration, structural deficiencies, incompatible roofing systems or other conditions may make roof replacement necessary.
The central point here is simple: Before automatically replacing an existing roof, determine whether its service life can be responsibly extended at substantially lower cost, while keeping existing materials out of landfill and still gaining the cool-roof benefits of a reflective membrane roof replacement.
REPLACE — When a New Roof Is Needed
When roof replacement becomes necessary, a building owner should consider what benefits the new roof should provide throughout its service life. Waterproofing, durability and compliance with building and energy codes remain fundamental. However, given BC’s increasingly hotter future, the roofing decision should also consider the additional benefits a new cool roof could provide the building, its occupants and the community surrounding it.
A low-slope roof installed today can remain in service for decades, during which Metro Vancouver is predicted to experience summer temperatures comparable to or exceeding those of present-day Southern California. Roof replacement therefore provides an important opportunity to select a system that responds more effectively to expected future climatic conditions.
Too often roof replacements involve the installation of essentially the same type of roofing system being removed. While this may be the familiar or conventional choice, it can overlook newer roofing technologies and the additional building-performance and climate-adaptation benefits they may provide.
For low-slope buildings, high-performance reflective membrane roofing provides one such alternative. In addition to substantially reducing solar heat absorption, these systems can provide durable waterproofing while helping reduce rooftop temperatures, heat transfer into the building and energy costs for cooling.
The central point here is also simple: If an existing roof needs to be replaced, don’t automatically replace it with what was there before. Consider whether a reflective cool-roof system can provide greater benefits over the service life of the new roof as it defends the building against a substantially hotter future climate.
POWER UP — Can the Roof Support Rooftop Solar?
A roofing project also creates the opportunity to consider whether a roof can support rooftop solar.
Cool Roofs and Rooftop Solar
Cool roofs and solar photovoltaic systems can work particularly well together. Solar panels generally operate more efficiently at lower temperatures, with reflective roofing providing a cooler rooftop operating environment. Where bifacial solar panels are used, a highly reflective roof can provide an additional benefit by reflecting solar energy onto the underside of the panels, with research reporting additional energy yields of 15% or more in some configurations.
South Coast Energy Resilience
A decision to incorporate rooftop solar can provide benefits extending beyond an individual building. The South Coast region is home to most of BC’s population and represents by far the largest share of the Province’s demand for electricity. Relatively little of this electricity, however, is being generated within the region. It is being produced elsewhere in BC or imported from the United States and transmitted to the South Coast via transmission lines that could be vulnerable during a major seismic event. This raises an important question: Could increasing the amount of electricity generated within the region help strengthen its energy resilience? Rooftop solar presents one opportunity to do so.
The contribution of any individual rooftop solar installation will be relatively small. However, thousands of installations distributed across homes, commercial and industrial buildings, schools, institutional facilities and other properties could collectively provide a meaningful new source of locally generated electricity, reducing the South Coast’s current heavy dependence on electricity being transmitted into the region and thereby providing greater energy resilience.
The potential value of greater energy resilience was demonstrated during the June 2021 extreme-heat event, when record electricity demand coincided with a significant increase in unplanned power outages. A major seismic event could result in much more widespread and prolonged disruption to the electrical system.
For these reasons, serious consideration should be given to increasing the availability of distributed, locally generated rooftop power as one component of strengthening the South Coast’s longer-term energy resilience.
Making Roofs Solar-Ready for the Future
Where practical, roofing projects undertaken today should either include rooftop solar or preserve the ability to install it at a later date. Solar-ready requirements reflecting this approach have already been adopted in jurisdictions such as California and through Toronto’s green-building standards.
The central point here is simple: Whenever a roof is restored or replaced, consideration should be given to whether it can also support rooftop solar—or be made solar-ready for the future.
©CoolRoofsBC 2026