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 We Have Made — and Continue to Make
Much of British Columbia's existing building stock was constructed at a time when reducing solar heat gain was rarely a consideration in the selection of roofing materials. As a result, dark, heat-absorbing roofs remain commonplace across our communities.
This is not only a legacy of past construction. New buildings continue to be constructed with predominantly dark roofing, even as BC experiences hotter summers and more frequent extreme-heat events.
The photographs below illustrate both situations. The established Kitsilano neighbourhood in Vancouver shows the cumulative result of past roofing decisions, while the newer North Langley development shows how similar choices continue to shape the roofs being installed today.
Every Roofing Decision Is an Opportunity
Roofs eventually require maintenance, restoration or replacement. New buildings require new roofs. Each of these decisions provides an opportunity to consider whether a roofing system that absorbs less solar heat would provide advantages for the building and the community.
Cool roofing does not require a single solution. Depending on the building and the condition of its roof, there are three practical opportunities to consider:
EXTEND
Restore and extend the service life of a suitable existing roof with a reflective roof-coating system.
REPLACE
When roof replacement is required, select a roofing system with appropriate cool-roof properties.
POWER UP
Consider how a cool roof can work together with rooftop solar and prepare the building for future energy opportunities.
START COOL — New Construction
The best time to consider cool roofing is before a new roof is installed.
For new construction, cool roofing can be incorporated into the original building design rather than considered later as a modification. Roofing type, solar reflectance, insulation, rooftop equipment and opportunities for solar energy generation can all be considered together.
A roof being installed today may remain in service for decades. Selecting an appropriate cool roofing system at the outset provides an opportunity to reduce solar heat absorption throughout that roof's service life, helping the building perform better during increasingly hot weather.
Other jurisdictions are already incorporating these considerations into new construction. California's building energy standards include cool-roof requirements for newly constructed nonresidential and multifamily buildings and require solar photovoltaic systems on many newly constructed residential, multifamily and nonresidential buildings, subject to specified requirements and exceptions. Where solar is not installed, solar-ready requirements can apply to accommodate
future installation.
The principle is straightforward: when a new building is constructed, consideration should be given from the outset to what contributions its roof can make beyond simply providing waterproofing.
For Existing Buildings — EXTEND · REPLACE · POWER UP
Existing buildings present different opportunities depending on the condition of the roof, the building's requirements and the owner's longer-term plans.
EXTEND — Cost-Effectively Extending the Service Life of Existing Roofing
A roof that remains fundamentally sound does not necessarily need to be replaced simply because its original surface is approaching the end of its expected service life or some leaking has begun to occur.
Where appropriate, a high-performance reflective roof coating can restore and protect an existing roof surface, extending its useful service life and converting a dark, heat-absorbing roof into a highly reflective, heat-rejecting surface — often at substantially less cost than complete roof replacement.
Roof restoration coatings are an established part of the low-slope commercial roofing market in the United States, where they are widely used to extend the service life of suitable existing roofs rather than replacing them. In British Columbia, roof restoration using reflective coatings remains a much
less commonly used approach.
Not every existing roof is suitable for restoration. Its condition, moisture content, drainage, existing roofing system and remaining structural integrity need to be properly assessed. But where conditions are appropriate, restoration can provide a cost-effective opportunity to extend the roof's service life while substantially improving its solar performance.
How Reflective Roof Coatings Work
Reflective roof coatings are engineered roofing systems, not ordinary paint. Suitable systems can restore and protect compatible low-slope membrane roofs and metal roofs. A highly reflective white surface reduces solar heat absorption while providing a weather-resistant protective layer.
Preparation, application and maintenance must follow the coating manufacturer's requirements. Where the underlying roof remains suitable, periodic recoating may provide further service-life extensions, helping defer complete replacement and keep existing materials out of landfill.
When Roof Restoration Is Appropriate
A roof should be assessed before restoration is selected. Its condition, moisture content, drainage, existing materials and compatibility with the proposed coating are important considerations.
Trapped moisture, failed insulation, extensive deterioration or structural problems may make replacement necessary. Before automatically replacing an existing roof, determine whether it can be responsibly restored and its useful life extended. Reflective coatings are not recommended for steep-slope asphalt shingles; when replacement is required, consider suitable cool-roof-rated shingles instead.
REPLACE — When a New Roof Is Needed
When roof replacement becomes necessary, consider what the new roof should provide throughout its service life. Waterproofing, durability and compliance with building and energy codes remain fundamental. Solar performance should also be assessed for its potential to reduce heat gain, improve occupant comfort and help the building prepare for hotter summers.
A roof installed today may remain in service for decades. Replacement creates an opportunity to assess available roofing systems rather than automatically repeating the previous choice.
Suitability depends on the local climate, roof assembly, building use, warranty, maintenance requirements and budget. For low-slope buildings, high-performance reflective membranes such as suitable TPO and PVC systems offer options that combine waterproofing with reduced solar heat absorption. Consider their measured solar performance alongside other project requirements and opportunities to coordinate the roof with rooftop solar.
If an existing roof needs to be replaced, consider whether a cool-roof system can provide greater benefits over the service life of the new roof.
POWER UP — Can the Roof Support Rooftop Solar
A roofing project also creates an opportunity to consider rooftop solar. Roof condition, remaining service life, structural capacity, equipment placement and future access should be assessed together. Coordinating roofing and solar decisions can help avoid later alterations and prepare the building for solar installation now or in the future.
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.
Local generation and backup power are related but distinct considerations. Most grid-connected rooftop solar systems shut down during a power outage. Supplying a building during an outage requires an appropriately configured backup system, generally including battery storage and equipment that safely isolates it from the grid.
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.
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.
Making Better Use of Land We Have Already Developed
The Provincial Government estimates that BC's demand for electricity could double by 2050. With opportunities for major new hydroelectric generation increasingly limited, substantial new sources of electricity will be required. Wind and solar developments, including projects already approved in BC's Interior, are expected to contribute to meeting this growing demand.
At the same time, British Columbia has millions of square feet of low-slope roofs on government, commercial and industrial, educational, institutional and residential buildings. Much of this is already-developed space which could potentially be used for solar electricity generation, thus helping to reduce the amount of additional land required for new energy development and the environmental and land-use impacts that can accompany it.
Greater use of rooftop solar on the South Coast could also increase the amount of electricity generated within the region, strengthening energy resilience and reducing reliance on electricity transmitted over long distances. When rooftop solar is combined with cool roofing, the two technologies can work particularly well together: cool roofing can improve the operating environment for solar panels while also reducing the building's own cooling-energy requirements.
03
Rooftop Solar Power Generation
Uses existing roof space for electricity generation with minimal additional land disturbance.
03
Wind Energy Development
Adds electricity generation, with land required for turbines, access roads and supporting
infrastructure.
03
Utility-Scale Solar Development
Generates electricity from larger ground-mounted arrays, requiring land for panels and supporting infrastructure.
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
