The Super Cool Roof Guide
We know that sitting in the hot sun is more pleasant in a white T-shirt than a black one. The same can be said for buildings – more and more scientific research is revealing how a white roofs are good for the planet, reducing the heat build-up in cities and in our homes. Fortunately, no aesthetic sacrifices are necessary if you’re opting for a white roof. A home with a white roof can be the envy of the neighbourhood.
Without doubt the future need for Cool Roofs as part of our urban landscape will become necessary and mandatory. As global temperatures rise, cool roof technology will become a frontline defences to rising solar heat, heat waves, increasing energy costs, rising carbon emissions and public and personal safety. Roofs are not always considered when looking at ways to improve building energy efficiency however, ‘cool roofs’ do more than simply protect a building’s occupants from the harsh environment.
For thousands of years the architecture of many ancient civilizations around the world has long recognized the benefits of light‐coloured external surfaces on buildings to improve the internal comfort levels in hot environments. The problem of global warming has renewed interest in products with low solar surface absorptance both in Asia, North America and Europe. There is a growing understanding that these products can provide a number of benefits including a reduction in the cooling and energy demand in summer, better and safer well being of the community, increased heat reflection in urban areas, reduction in the heat island effect and a reduction in greenhouse gas emissions.
There are a range of options for the application of Cool Roofs, however this Super Cool Roof Guide is focused on Super Therm® Solar Heat Block Coating and its outstanding worldwide success to mitigate heat into buildings, vehicles, transportation, containers and more. Super Therm® goes a long way to assisting in the proven reduction of energy use and therefore the Urban Heat Island effect. With one of the world’s highest TSR ratings of 96.1, Super Therm® stands out from the crowd of heat reflective paints as a true heat block coating.
A cool roof is one that strongly reflects sunlight and minimises the amount of heat generated when the sun heats its surface. It also cools itself by emitting radiation to its surroundings when the sun sets or weather changes. The technology means roofs should stay cooler, and reduce the amount of heat conducted to the building it shelters, contributing to more stabilised internal temperatures (Australian Architecture and Design).
A Super Therm® cool roof does much more:
- Reducing the heat load into a building reducing CO2 emissions
- Reduces energy use and consumed
- Reduces the urban heat island effect
- Protects the roof as an asset from thermal shock
- Adds fire protection
- Mould and mildew reduced
- Sound reduction
The Cool Roof conversation should be unnecessarily complicated. If you want to know how complicated the conversation is regarding, read this article by Cameron Jewell on Cool roofs versus dark roofs: special report. On its website Monier says: “Light coloured roof tiles keep cooler than darker coloured roof tiles and this cooler temperature can mean reduced energy costs for cooling a home or building.” A spokeswoman for Monier in the article said that the company had “a fantastic range” of light coloured tiles, however customer preference was heavily skewed towards dark tiles. In the same article the spokeswoman also unfortunately said that building scientists who were part of parent company CSR said that colour did not make a significant difference to thermal performance of a house because roof insulation formed a thermal barrier. This gives evidence of the mis-messaging the customers receive regarding roof colours, thermal protection and benefits of Cool Roofs.
In a recent study Cooling Darwin: UNSW plan to fight climate change, Scientia Professor Mat Santamouris outlined urban overheating threatens the lives of people in Darwin, but researchers from UNSW’s Faculty of Built Environment have calculated how many lives could be saved by changing the city. “We found that mortality increased by 5% for every 1°C increase in daily maximum temperature.” Urban overheating has a serious impact on human health and the economy because it increases the concentration of urban pollutants, affects urban air quality, increases energy consumption for cooling purposes and raises carbon dioxide emissions. He said the annual cooling load saving from greenery is an estimated 88.4GWh, while the application of cool roofs and pavements is 214GWh – UNSW Newsroom – Full Report pdf.
Darwin City Final Report states: The mitigation potential of reflective roofs depends on several parameters like the local climate and in particular the solar radiation intensity, the ambient temperature and humidity, wind speed and cloud cover, optical parameters like the reflectivity of the roof to solar radiation and the emissivity factor, thermal parameters like the thermal capacity and the U-value of the roof, and technical parameters defining the ageing process of the reflective roofs – Page 60 – Full Report pdf.
The U-value measures how effective a material is an insulator and must be a consideration for standardisation of heat reflective paints and heat block coatings to part of the overall consideration of the thermal efficiency of all products. Understanding the Heat Load of a cool roof is critical and gives consumers the full picture of thermal benefits a product. Quite often there is just a focus on the SRI (Solar Reflective Index) which does not take into consideration the heat load penetrating into the substrate and transferring into the building therefore this is not giving the full and complete picture.
According to Architecture and Design, a whole range of design elements fall under the umbrella term of “cool roofs”. Essentially, a cool roof is one that reflects the suns heat and emits absorbed radiation back into the atmosphere at a higher rate than standard materials, literally staying cooler than a standard roof. This reduces the amount of heat transferred into the building below, keeping it at a more constant temperature however without a standard such as U-value no one is able to conclusively state what their product actually achieves in thermal efficiency. Similar to the R-value, the U-value aims to measure thermal transmittance into a building.
Cool roofs are reflective surfaces designed to reflect more solar radiation and absorb less heat than a standard roof – Victorian Energy Saver Program. ‘Cool roofs’ use roofing materials with high solar reflectance and thermal emittance, reducing the heat absorbed from the sun and increasing the heat radiated out to the sky. Cool roof technology reduces the amount of heat transmitted into buildings on hot days, and thus the amount of air-conditioning required for cooling. Their widespread use across a neighbourhood or precinct can mitigate the urban heat island effect (CRC).
There are a number of ways to use roofs to decrease the environmental toll of our built environment and to begin to use urban infrastructure as an agent of adaptation and environmental services. Installing white roofs, cool roofs, vegetated roofs, solar hot water, or photovoltaic panels can all be effective ways to improve the energy and environmental performance of roofs.
By reducing the fraction of incident sunlight that is converted to heat by the roof, cool roofs can help cool buildings, cities and the planet. The most popular type of cool roof is a bright white roof, cool coloured roofing materials have become available for steep-sloped roofs (mostly residential). Compared to white roofs, cool coloured roofs are less solar reflective and a bit more expensive.
Cool roofs are an order of magnitude cheaper to install and pay back faster than vegetated roofs. Super Therm® as an example offers 95% solar heat block amongst a range of other benefits that reduces electricity use in air-conditioned buildings, increase thermal comfort in unconditioned buildings, reduce the urban heat island effect, and by saving energy helps mitigate global climate change.
It started with an article on a study out of Berkeley Lab in California, which concluded that white roofs outperformed black roofs economically as well as environmentally. It called for the phasing out of dark roofs in hot climates, especially those prone to heatwaves. This would save energy costs, protect against the urban heat island effect and tackle climate change – The Fifth Estate
When it comes to the solar passive design of your new home, a dark-coloured, high solar absorptance roof is not a good idea, as it will make it more difficult to achieve a thermally comfortable internal environment during summer. Even if you intend on installing air-conditioning, a high solar absorptance roof will mean the air-conditioning will have to work harder to cool down your home, meaning higher electricity costs and increased carbon emissions – The Fifth Estate
“Rapid deployment of cool materials represents one of the largest and most cost-effective opportunities we have to counter global warming, improve health and strengthen security.” U.S. Secretary of Energy, Steven Chu – (Global Cool Cities Alliance)
In an insights brochure, Boral stated it was “seeing a move towards lighter colours that blend with the natural environment” (source). Dr Chris Reardon, principal author of the Your Home guide said “Research shows that light coloured roof tiles can lower the air temperature in the roof space by up to nine degrees compared to dark tiles.”
Dr Reardon warned that when designing houses, instead of taking into account current climates it would be prudent to look at projected temperatures over the 50-80 year lifetime of a house, with CSIRO research predicting temperatures up to 4°C warmer on average by 2100. (source)
Need for the future change
- Legislation that prevents dark roofs for the future
- Mandatory for public buildings for cool roofs
- Education for property developers
- Mitigation based on best technologies and plans – not myths
- Reduce cultural norms for dark roofs
- Industrial areas and large span roofing helps improve working environments
- Necessity will drive cultural change
- Cost of power will drive change
- Government to provide stimulus for cool roof technology – reduces pressure on energy security
- Put cool roof technology in the building codes
- Government lead by example put on your buildings; show its real
- Ensure all tenders cover efforts respondents will take to reduce heat
Super Therm® Heat Block Coating Cool Roof Benefits:
Cool Fact #1 – Reduced cooling energy load in summer
A. Cool roofs are designed to be used in summer and warmer environments to reduce solar thermal loads through roofs and walls.
Cool Fact #2 – Reduced energy power bills
A. The reduction in the use of energy naturally equates to a reduction in energy power consumption and power bills. Con Edison research from New York stated a 6° reduction in the thermostat produces a 39% reduction in utility costs. Therefore a KW savings = Actual Dollar Savings.
Cool Fact #3 – Decrease air conditioning demands in buildings
A. A Cool roof reduces the need for mechanical air conditioning demands in buildings. Without the pressure of reducing temperatures due to excessive heat, the need for keep the building cool is reduced.
Cool Fact #4 – Lowers indoor air temperatures that are not air conditioned, such as garages or covered patios
A. Cool roofs solves the challenge in areas that cannot be easily cooled mechanically. A simple and passive solution to areas where mechanical cooling is a difficult to apply or manage.
Cool Fact #5 – Decreases roof temperature
A. The less solar absorption by a roof ensures the thermal temperature in a roof space is reduced along with the heat load. Reducing roof temperatures ensures less heat is transferred into the building.
Cool Fact #6 – Extend roof service life, lower roof maintenance costs and reduce thermal shock
A. Thermal shock is the unseen asset expense on a building the continuous expansion and contraction of metal roofs causes corrosion. A cool roof stablises the roof sheeting therefore reducing thermal shock. Super Therm will also protect the roof further ensuring you can get another 30+ years of life savings thousands in re-roofing.
Cool Fact #7 – Reduce climate change impacts and greenhouse gas emissions
A. A Cool roof has been proven to reduce CO2 emissions. The reduction on need for mechanical cooling ensures there’s less energy used. The CO2 results from reduced energy consumption has been proven time and time again.
Cool Fact #8 – Reduce local air temperatures benefiting the urban heat island effect
A. A critical part of Cool roofs is the proven reduction of local air temperatures. Roofs cause between 25-35% of the urban heat island effect and less heat stored by roofs also reduces city and neighbourhood temperatures…particularly at night.
Cool Fact #9 – Lower peak electricity demand, which can help prevent power outages
A. The reduction in energy consumption naturally lowers the demand for electricity but also peak energy. This reduction of energy therefore reduces the pressure on power failures.
Cool Fact #10 – In warm, moist locations, Super Therm cool roof surfaces reduce algae or mould growth
Cool Fact #11 – Works best in warm to hot environments
Cool Fact #12 – Increase the life of air conditioning systems
Cool Fact #13 – Increases the efficiency of bulk insulation by reducing heat load
Cool Fact #14 – Reduced air pollution
Cool Fact #15 – Improved human health and comfort
Cool Fact #16 – A cool roof coatings can be installed on any building
Cool Fact #17 – Can be tinted to meet design, aesthetic or council requirements within reason
Cool Fact #18 – Cool roofs can the same per meter square than the cheapest polypropylene carpet
Cool Fact #19 – Reduce condensation
Cool Fact #20 – Safe for use around humans and animals
Cool Fact #21 – Lasts over 30 years
Cool Fact #22 – Improves solar systems feed in tariffs
Cool Fact #23 – Meets the needs of YourHome recommendations
Cool Fact #24 – Ease of blocking heat over lifting roof sheets or replacing the roof
Cool Fact #25 – Short payback period
A. Cool roofs are typically low cost investments. If the roof needs to be replaced anyway, choosing a white coloured material often costs the same as a dark coloured alternative
Cool Fact #26 – Used around the world
Cool Fact #27 – Beware of “paint”
A. Paints are typically cosmetic in nature and significantly thinner applications than coatings and coatings are more reliably weather resistant.
Cool Fact #28 – Energy star and CRRC
Cool Fact #29 – The winter heating penalty occurs in most temperate areas
A. In almost every case it is less than the cooling energy savings. While there usually is an increase in the demand for heating in winter, for cool roofs introduced in the right locations and the right building types this so called “winter penalty” can be insignificant and is much lower than the reduction in the cooling load (source).
Cool Fact #30 – Improve the health and productivity of livestock
Australian Government’s Nationwide House Energy Rating Scheme (NatHERS)
To be effective, passive cooling needs to cool both the building and the people in it – Australian Government. According to the Australian Government, a 7 star rating is achievable with basic inexpensive materials such as aluminium windows and single glazing when the right design principles are applied—such as passive design and appropriate use of insulation and material selection.
The Building Code of Australia doesn’t take into consideration new and next generation solar heat block technology such as Super Therm® that blocks the heat entering the structure. NatHERS say in order to achieve a 7 Star rating building you need a roof colour of Surfmist® in Adelaide, Brisbane, Canberra, Darwin, Sydney and Windspray® in Melbourne and Hobart.
The summer heat in Melbourne can exceed 40°C so to have a near 50% grey roof in Windspray® as a specified colour for a hot environment isn’t energy efficient. Interestingly Surfmist® is the lightest colour in the Colorbond® range above and is recommended for the rest of the country except Perth that has Classic Cream®.
Super Therm® Colorbond® Colour Roof Tints
Super Therm® can be tinted to the lighter range of COLORBOND® colours. Naturally due to physics, the darker the colours the less thermal efficient thermal barriers become which is the same for heat block coatings. Therefore we recommend these COLORBOND® colours that help improve thermal solar heat barrier and make your roof look fantastic.
Super Therm® is an egg shell white with a Total Solar Rating of rating of 96.1 (stops heat), Solar Reflective Index rating of 102 (reflects light and emits heat) and BTU rating of 99.5% (Blocks infrared), it can be tinted with water base dies to light colours by your local paint store.
IMPORTANT: Any tints and darker colours will cause a reduction in solar heat performance which is then influenced by the colour and the environment. The chart below is a colour guide to the reduction of efficiently with tints applied to Super Therm®. See COLORBOND® solar absorption ratings.
7 Star rating and beyond
The application of Super Therm® to a roof would take the energy rating beyond 7 Stars, proven to save up to 20-50% in energy use (Industry testing) while lowering CO2 emissions and extending roof life. Super Therm® ceramic heat block coating technology blocks 95% of solar heat entering a building and used globally…that’s a game changer!
NEOtech Coatings Articles
- Cool Surface Technology
- Cool Roof Australia
- Urban Heat Island Effect
- 7 reasons to apply a cool surface and roof coating system on your building
- White is the New Black in Eco-Friendly Roofs
- Effects of Urban Surfaces and White Roofs on Global and Regional Climate
- Driving Increased Utilisation of Cool Roofs on Large Footprint Buildings
- What Makes a Cool Roof Cool
- Cool Roofs and Heat Reflective Paints – Dr John Pockett Uni SA
- Cooling Darwin: UNSW plan to fight climate change – Scientia Professor Mat Santamouris
- Victorian Energy Saver Insulation and Cool Roofs – PDF
- Home energy efficiency could be improved significantly through simple tweaks like roof colour
- Adelaide’s urban heat islands are compounding the effect of heatwave conditions
- South Australia’s Cool Roof Regulation Discussion Paper
- What makes a cool roof “cool”?
- The Truth about Dark Roofs and Cool Roofs
- Cool Roofs Versus Dark Roofs Special Report
- Department of Energy USA – Cool Roofs
- City of Melbourne Cool Roofs 2 page Guide
- US Department of Energy – Guide to Cool Roofs
- Guidelines for Selecting Cool Roofs
- A Practical Guide to Cool Roofs and Cool Pavements (pdf) – web
- Roof and Wall Thermal Design Guide
- Insulation and cool roofs