Keep walls cooler in summer
Heat reflective
By reflecting more of the sun’s heat, your home feels cooler in summer and your walls stay protected through the hottest days.
The summer stress
UK homes are built to hold heat, not release it. That helps in winter, but during warmer spells exterior walls absorb sunlight, warm up fast and stay hotter for longer. This makes rooms feel warmer and causes the wall to expand and contract, putting more strain on masonry and paint.
Cold and wet weather still pose the greatest risk to wall health, but the impact of heat is easy to overlook. Many people assume heat is not a problem in the UK, yet warm periods are lasting longer and placing more pressure on exterior walls than ever before. With the UK now seeing longer warm periods, managing heat is an essential part of protecting exterior walls.
A smarter way to protect walls
Despite government guidance highlighting that external walls can absorb large amounts of heat and raise indoor temperatures, most masonry paints don’t address this, leaving many homes to take in more heat than they need to. Thermal performance is not part of standard testing, so products rarely report how they behave in warm conditions.
Our mission is to protect your home through everything the Great British weather brings, from long wet spells to the warmer days that place heat on exterior walls. That’s why we test Emperor Masonry Paint far beyond standard masonry requirements. Independent analysis discovered that it had ‘extremely high solar reflectance’, sending much of the sun’s heat away rather than letting it sink into walls. This helps keep surfaces cooler and more stable when the weather warms.
Source: Department of Energy and Climate Change, Guidance On Preventing Overheating in Homes.
Tested to handle real weather
Testing was carried out by Sonnergy, a leading independent specialist testing laboratory in accordance with ASTM E1920-01, the internationally recognised standard for measuring solar reflectivity.
The results showed that Emperor Masonry Paint in the colour white reached a Solar Reflectance Index value of 86%, a level usually seen in specialist high-reflectance coatings. For your home, that means walls absorb less heat in summer, rooms stay cooler and the surface takes less strain throughout even the hottest days.
‘White’ was selected as the benchmark colour for testing, representing the highest reflectance potential. Reflectance reduces progressively with darker colours.
Warmer in winter and cooler in summer
When you hear that a paint reflects heat in summer, it’s natural to wonder whether it makes your home colder in winter.
Heat is lost in winter due to moisture, as wet walls cause heat to escape quicker than dry walls. Thanks to our nano-technology, walls stay dry and retain heat through colder months.
Together, these benefits keep your home protected throughout the year, staying cooler in summer while holding more warmth in through winter.
What it means for your home
Our homes deal with heat, moisture and temperature shifts throughout the year. While our cutting-edge nano-technology helps protect your home from rain, Emperor Masonry Paint’s high solar reflectance protects through the warmer weather. Together, they keep your home protected today and prepared for the more unpredictable weather we face in the years ahead.
- Cooler rooms in warm weather
- Protection against the stress heat puts on exterior walls
- Reduced heat stored in the day means a more comfortable night
- Paint that stands up to heat year after year
- Peace of mind that your walls are protected when temperatures rise
Does colour change the solar reflective performance?
Yes, lighter colours reflect more heat. Our testing was conducted on Emperor Masonry Paint in ‘White’ as the lightest colour in our colour range. The solar reflectance performance reduces as the colour darkens, as darker colours absorb more heat.
What homes does this benefit most?
Homes with high levels of sun exposure benefit the most from solar reflectance. The Department of Energy and Climate sets out in its Guidance On Preventing Overheating In Homes, that solar reflectance is ‘effective on older properties with solid brick walls’, which absorb more heat in warm conditions.
Having said this, any property with sun-facing walls, limited shading or strong afternoon exposure will benefit from high solar reflectance on their exterior walls, with the level varying depending on your home and conditions.
How does heat absorbing into exterior walls affect indoor conditions?
When the exterior walls of your home heats up, that stored heat passes inward through conduction. The warmer outer surface drives heat toward the cooler interior, which raises the indoor temperature later in the day. This effect is stronger in solid walls because heat moves straight through the masonry. Cavity walls slow the transfer, but the outer brickwork still warms under strong sun and passes heat inward over time.
How does high solar reflectance protect the wall?
Exterior surfaces move during temperature changes in a process called thermal movement. By reflecting much of the sun’s heat, Emperor Masonry Paint helps reduce expansion and contraction of the wall, lowering the stress put not only on the wall but the paint itself. This supports the extreme durability of Emperor Masonry Paint, with a proven 25 year performance and backed by a lifetime guarantee.
Read more about our testing & certifications
Our Testing Hub
Read a comprehensive summary of all of our extensive independent testing results and industry leading certifications.
BBA Approved
We are extremely proud that Emperor Masonry Paint has been awarded the BBA Agrément Certificate, a mark of excellence based on national and European standards.
UKAS Accredited Independent Testing
Saying how good our products are is one thing, showing it is another. We wanted to be able to demonstrate the superior performance, so we have had our products independently tested by a world leading UKAS Accredited laboratory.