Add My Company
With the growing emphasis on energy-efficient buildings and green building rating systems in the UK, a cool roof can contribute significantly to obtaining BREAAM-certification. Cool roofs or reflective roofs live up to their name by reflecting a substantial portion of the sun’s rays away from the structure and keeping it cooler, as opposed to transmitting heat to the interior.
Dark-coloured roofs tend to absorb a significant amount of solar energy, leading to the accumulation of heat within a building. This results in increased air conditioning usage or enhanced ventilation in hot summer months. In contrast, the reflective white surface of a cool roof minimises “solar gain” and prevents overheating. Several modelling studies on London are even suggesting that “cool roofs could reduce maximum air temperature by 1 °C in summer”.[1] Clearly, installing reflective roofs offers both environmental and financial advantages.
HEAT BUILD-UP IN BUILDINGS
In the UK, the urban heat island effect “for a number of cities has been estimated at 1–2 °C in winter, and 2–3 °C in summer.”[2] Cool roofs reduce this effect, as do other measures to adapt the urban fabric (which is the main cause of the urban heat island effect) like “improved urban planning, modifying building materials, increasing green/blue space and reflective ‘cool’ facades.”[3]
With the Met Office recording “tropical nights” (meaning that temperatures do not drop below 20 °C) during all but three years since the start of the century (whereas only half of the years between 1961 and 2000 had those nights) and pointing to “higher maximum temperatures and longer warm spells in recent years”[4], it adds up to a compelling reason to consider specifying a cool roof.
In a 2021 study, researchers from the Institute for Environmental Design and Engineering at University College London and other institutions suggest that “benefits of cool roofs may increase in future, with a doubling of the number of heat-related deaths avoided by the 2080s compared to summer 2006.”[5]
EFFECTIVE REFLECTIVE ROOF DESIGN
Reflective roofs are typically incorporated into new construction projects, except when a renovation project specifically aims to reduce energy consumption.
For architects and designers, there are no inherent technical obstacles to implementing a reflective or cool roof, although certain design factors should be considered. To maximise the effectiveness of a cool roof, the primary objective is to keep it as white and as clean as long as possible.
Attention to detailing is crucial to ensure that slopes and falls function correctly, and dirt does not accumulate. Given the high levels of rainfall in the UK, it is essential to design the roof with effective drainage systems to ensure that rainwater is efficiently channelled away.
COOL ROOFS AND FUNCTIONAL ROOFS COMBINED
To achieve sustainable building design, architects can combine cool roofs with all functional roof types, such as green, solar or blue roofs. This approach minimises the building’s overall environmental impact and can help to comply with local building regulations, either promoting biodiversity (green roofs), producing renewable energy (solar roofs) or managing water resources (blue roofs). Buildings can contain several types of functional roofs, or feature a cool roof, green roof and solar roof all in a single project.
SOPREMA’S COOL ROOF SOLUTIONS
No matter the specific waterproofing specified by the architect or designer, Soprema can provide bespoke cool roof waterproofing systems that meet the requirements of each project. We offer reflective roof solutions in various materials, including bituminous, with the SOPRALENE OPTIMA 4 GF C3 FR WHITE membrane; liquid, with ALSAN 970 CR (a white-pigmented reflective layer for the ALSAN PMMA ReflectRoof system) and synthetic, through our range of FLAGON ENERGY PLUS membranes.
For more information on USING COOL ROOFS TO REDUCE ENERGY COSTS AND HEAT ISLANDS talk to SOPREMA UK