Australia’s Cool Roof Building Energy Efficiency Opportunity
Australia’s cool roof opportunity
NEOtech Coatings Australia
September 13, 2021
A study shows four Australian states currently have the highest energy prices in the world, with South Australia the most expensive followed by NSW, Queensland and Victoria (Center of the American Experiment, 2018 – pdf). Less than two decades ago, South Australia generated all its electricity from fossil fuels. In 2020 renewables provided a whopping 60% of the state’s electricity supply (The Conversation, 2021). As energy prices may rise and unprecedented global temperatures are rising, the Australian Government response is it’s working towards a net-zero 2050 emissions target. In the meantime, the question becomes where’s the opportunity to protect ourselves from future extreme heat events which also reduces energy consumption while minimising the urban heat island effect and Australia’s CO₂ emissions?
High performance, thermal heat barrier heat block coatings have proven worldwide to address 21st century environmental heat challenges. The next generation industry provides real solutions that can support traditional bulk and fibreglass insulation, however Australia’s building standards have a blindspot where these significant energy savings can be made, particularly against rising and significant heat events.
Undiscovered high performance, high emissivity formulated ceramic coatings developed with NASA are set to revolutionise the concept of a new generation products that stops heat load on a building’s envelope and go a long way to the Australian Government’s commitment to the Paris Agreement to reduce its emissions by 26 to 28 per cent from 2005 levels by 2030. Instead, since 2015 our emissions have been going up year on year (March & ABC News, 2019).
Helping traditional insulation block the heat
Without doubt, traditional insulation is extremely important in all parts of our world where energy is consumed and managed. Traditional Insulation is utilised in buildings for conserving energy, creating comfort, reducing noise and reducing demands on heating and cooling through air conditioning. Traditional insulation materials are produced in many forms with long established fibreglass batts being the most utilised worldwide.
Tested and proven ceramic heat block coatings are calling for a rethink on the perception of coatings used to reduce and block thermal heat load before it enters into a building’s envelope. Similar to heat technology ratings in the glass industry, the potential U-value has merit, the greater a window’s resistance to heat flow and the better its insulating value (Australian Government n.d.). Revolutionary heat block coating technology has been tested internationally since 1989 and blocks 95% of the sun’s solar heat from being absorbed into the envelope of a building. It’s been tested to stop 99.5% of infrared heat which makes up 53% of solar heat (Glass, n.d.) and lasts longer than 20 years without flaking, peeling or cracking on the surface.
The proven effectiveness of this solar heat block technology isn’t yet part of the mainstream conversation in Australia to reduce CO₂ emissions, save energy, reduce landfill, improve comfort, reduce power bills, protect building assets and reduce the urban heat island effect in our communities until now.
Desperate need for heat resistance in buildings
University of South Australia research associate Dr Gertrud Hatvani-Kovacs co-authored a paper calling for the Building Code of Australia to encourage designs that are heat stress-resistant. “Buildings were rated according to their annual energy consumption and while they may perform very well during winter time and consume much less for heating, their cooling demand was still relatively high” Gertrud said (Sutton & ABC News, 2018).
A study found that new energy efficient homes can actually be less resistant to heat than older double brick homes so Australians are becoming more reliant on air conditioning with implications for power use and health sparking calls for changes to the relevant codes. The current building code doesn’t necessarily encourage more heat resistant buildings and just concentrates on energy efficiency. We would need not just an annual energy threshold to be stipulated in the building code but separate heating and cooling threshold (Winter, 2018).
As a country, Australia needs buildings that are energy efficiency and heat stress resistant, however there’s a determined national focus on solar panels, R-values, energy efficient appliances and buildings along with better power prices from retailers, yet there’s no intentional conversation about cool roofs in Australia. This is a significant blindspot and opportunity! Thermal heat block coatings at the building’s envelope stop the heat load before it enters the roof space which make up over 25-35% of where heat is gained, particularly in summer.
The 2013 report by the National Climate Change Adaptation Research Facility, A Framework for Adaption of Australian Households to heatwaves authored by 23 leading Australian academics from the University of South Australia, University of Sydney and Queensland University of Technology recommended modifying roofs by increasing solar reflectance, adding reflective foils and increasing thermal insulation. While traditional insulation slows the heat load stopping the solar energy at the roof is the key.
In the last decade, consideration has also been given to the reflectivity of solar radiation from the roof and the impact of reflective foils. There is little doubt that traditional insulation within the roof has significantly reduced the cooling energy use in Australian homes. However, existing practices and regulations do not fully account for the actual heat transfer processes that occur, and Australia remains behind most of the developed world in this area.
The report continues according to the BCA, the thermal resistance or R value of traditional insulation is based on AS/NZS 4859.1:2002 which requires measurement of the R value at 23°C. However, no consideration has been allowed in the BCA for the degradation of the R value due to temperature or time. As stated in AS/NZS 4859.1:2002, the R value can degrade by 0.49%°C which, during peak summer, can represent a reduction of 14%. A fixed R value is also applied in AccuRate (NCCARF, 2013)
Given academic research and recommendation on utilising reflectivity of solar radiation to prevent heat load and the loss of efficiency of traditional insulation there will be increased demands and reliance on air conditioning. Inefficiently designed buildings means the release of waste heat into the atmosphere contributing to the urban heat island effect. As the world gets hotter, buying an air conditioner is ironically becoming the most popular individual response to climate change, and air conditioners are power-hungry appliances: a small unit cooling a single room, on average, consumes more power than running four fridges, while a central unit cooling an average house uses more power than 15. “Last year in Beijing, during a heatwave, 50% of the power capacity was going to air conditioning,” says John Dulac, an analyst at the International Energy Agency (IEA) (Buranyi, 2019).
There are just over 1 billion single-room air conditioning units in the world right now – about one for every seven people on earth. Numerous reports have projected that by 2050 there are likely to be more than 4.5 billion, making them as ubiquitous as the mobile phone is today. The IEA projects that as the rest of the world reaches similar levels, air conditioning will use about 13% of all electricity worldwide, and produce 2 billion tonnes of CO2 a year – about the same amount as India, the world’s third-largest emitter, produces today (Buranyi, 2019). More CO2 means further increases in greenhouse gas emissions and a hotter planet.
A presentation by Dr John Pockett from the Barbara Hardy Institute, University of South Australia on ‘Cool Roofs and Heat Reflective Paints’ stated ‘cooling efficiency is much less that heating and falls off very quickly as the ambient temperature increases, being about half its maximum when we have a very hot day.’ (Pockett, N.D.). This indicates that air conditioners need to work twice as hard the hotter it gets pulling in hot ambient air to convert to cool air, therefore doubling power consumption in the heat. Air conditioners stacked on top of each other are drawing hot air even more like a wall of fire. Knowing there’s an imminent increase globally in air conditioning sales and consumption and therefore CO2 emissions a smart and strategic strategy in cool roofs with proven, long term benefits is urgently needed to combat future heat challenges.
Urban heat island effects gaining Government attention worldwide
An urban heat island, or UHI, is an urban or metropolitan area that’s a lot warmer than the rural areas surrounding it due to stored heat energy. Urban heat islands are created in areas that have lots of activity and lots of people. There are many reasons for UHIs. When houses, shops, and industrial buildings are constructed close together, it can create a UHI. Building materials are usually very good at insulating, or holding in heat. This insulation makes the areas around buildings warmer (National Geographic Society, 2012). On hot days, asphalt roads contribute to heating cities and urban areas, known as the urban heat island effect. It can also impact retail trade for businesses near urban heat islands and increase energy and maintenance costs for surrounding buildings (City of Adelaide, 2020).
As an example, an article by Tanya Roe, Senior Consultant, Sustainability, City of Adelaide “Using seal coats to reduce urban heat“ stated in 2018 the Resilient East climate change partnership (eight councils in central-eastern Adelaide plus the Government of South Australia), along with the City of Salisbury, commissioned The Collaborative Heat Mapping for the Eastern and Northern Adelaide Project. A key finding from the study was that non-shaded asphalt roads are 4°C hotter than the average land surface day temperature, and they bank the heat and release it at night, becoming the hottest night-time surface (Roe & City of Adelaide, 2020).
Tanya states “hard surfaces typically account for the urban heat island effect in cities. Roofs typically account for 20-25% and pavements 40% of city surfaces, each absorbing 80% of sunlight reaching them and converting it into heat. There’s a range of cool materials being used, trialled and developed, which include low heat conductivity (conducts heat less into its interior), low heat capacity (stores less heat in its volume), high solar reflectance (albedo) and a high level of embodied moisture to be evaporated or filtrated into the soil.”
Urban heat island amongst other serious consequences produces higher air pollution, increased nighttime heat, increased urban temperatures and higher energy consumption and also adversely affects human health. Humans are negatively impacted because of increased general discomfort, exhaustion, heat-related mortality, respiratory problems, headaches, heat stroke and heat cramps. Urban heat islands can also worsen the impacts of heatwaves (Conserve Energy Future, 2017).
Although a global problem, the reason for the concern is the forecast for the Adelaide CBD, littlelone the rest of the world in Adelaide, South Australia, projections are:
- Annual average maximum temperatures to increase by 1.6°C by 2050 and 2.3°C by 2070
- Days over 35°C to increase from 20 days per year to 47 (38-57) days per year by 2090
- Days over 40°C to increase from 3.7 days per year to 16 (12-22) days per year by 2090
The Australian Bureau of Meteorology data indicates that 2019 recorded 38 days over 35°C and 17 days over 40°C. Hotter climates means more power consumption and more discomfort. The Climate Council said “Climate change is making hot days and heat waves more frequent and more severe. Since 1950 the annual number of record hot days across Australia has more than doubled and the mean temperature has increased by about 1°C from 1910.” (King & The Conversation, 2017). Specifically, there has been an increase of 0.2 days/year since 1957 which means, on average, that there are almost 12 more days per year over 35°C. More people die from heat waves than all the other natural hazards combined (Winter, 2018).
Councils like the City of Adelaide and City of Parramatta and many others in Australia are trying to plan for that heat nightmare according to Sebastian Pfautsch, a researcher at Western Sydney University who specialises in projects to mitigate urban heat. Pilot projects are testing approaches such as painting road surfaces with heat-reflective paint to retro-fitting playgrounds with materials to protect children from excessive ultraviolet light (Cadman & Bloomberg Green, 2020).
The urban heat island effect is prevalent in every Australian city and around the world and has been shown to be exacerbated by climate change. Countries are becoming increasingly urbanised and the global population is projected to be 70% urban by 2050 (Ma, Goldstein, Pitman, Haghdadi & MacGill, 2017) which will continue to grow the challenges of UHI into the future.
To show the serious nature of UHI effects in cities globally, the US introduced the Preventing Health Emergencies and Temperature-related (HEAT) Illness and Deaths Act of 2020 (Wiltshire-Gordon & U.S. Green Building Council, 2020). The proposed legislation aims to statutorily authorise the National Integrated Heat Health Information System Interagency Committee (NIHHIS) to address extreme heat in the United States. The HEAT bill would also establish a $100 million community heat resilience grant program within NIHHIS to support urban climate mitigation efforts. Projects eligible for grants include those using cool roofs, cool pavements, urban trees and building HVAC (Heating, Ventilating, and Air Conditioning) retrofits.
Research from the Smart Surfaces Coalition in the US shows that implementing citywide smart surfaces like cool roofs, green roofs, solar roofs and permeable pavements could reduce urban heat by 3-5 degrees, cut greenhouse gas emissions by up to 15%, create 250,000 local jobs, and save cities $700 billion in energy and health costs over the next three decades (Smart Surfaces Coalition, 2018).
The Cool Road programs strategies are similar in principle with regards to roofs and buildings which are accountable for 25-35% of the urban heat island effects (C40 Cities, 2016). While leading governments around the world like the City of Los Angeles, Tokyo Metropolitan Government, and in Australia are investing in Cool Road programs, the conversation of Cool Roofs is still undeveloped and a blindspot.
Governments are now collecting data on the significant impact urban heat island with the solution being in ‘light colours’ as a fundamental, yet there’s far more advanced technologically and extensively proven heat block coatings solutions available that seriously benefit CO₂ emission reduction, human comfort, asset protection, energy use reduction, long term sustainability and block heat.
Roof surfaces which absorb high amounts of solar radiation can readily reach temperatures of 80°C in hot weather. This temperature represents the driving force of the heat flow into the building. Roof surfaces which absorb low amounts of radiation can dramatically reduce this temperature, bringing it closer to the ambient temperature (NCCARF, 2013).
The blindspot in Australia’s energy saving conversation
Dr Hatvani-Kovacs says Australia’s building codes support energy efficiency but not “necessarily encourages heat-stress resistance” (Sutton & ABC News, 2018), The Australian Government’s Nationwide House Energy Rating Scheme (NatHERS), The Australian Government Your Home: Australia’s Guide to Environmentally Sustainable Homes and the Building Code of Australia don’t take Cool Roofs into consideration or next generation heat block coatings and reflective paints technology. Coatings like Super Therm® block the initial thermal heat load and stop the buildup of heat at the surface. This helps the fibreglass insulation become more efficient which stores the heat. This directly reduces the heat entering a building which positively contributes to the reduction of UHI as stored heat isn’t released into the environment or building at night.
There are no standards or education set for how thermal solar heat block coatings or reflective paints are rated. Although parts of the industry use Solar Reflective Index (SRI), this doesn’t measure thermal heat transfer or load into the building or their U-values, therefore showing the true energy savings benefits. No matter the emissivity number in SRI, the surface loads all the heat which then transfers through. Thermal emissivity is the infrared heat measured which is not blocked but re-emitted from the substrate through the paint that’s allowed it to already be absorbed. It’s like having an umbrella made from a flyscreen that allows 100% of the rain through while trying to measure how quickly you can dry while still being rained on. This is how the Solar Reflective Index is determined through reflectivity and emissivity…it doesn’t add up or connect to the purpose of blocking heat for true energy efficiency.
Your Home acknowledges that 25-35% (Australian Government, n.d.) of heat gain comes through the ceiling of a home and yet the only reference in YourHome.gov.au to cool roofs and sustainability is the “shading of wall and roof surfaces is therefore important to reduce summer heat gain, particularly if they are dark coloured or heavyweight. Light coloured roofs can reflect up to 70% of summer heat gain” (Australian Government, n.d.). This highlights the urgent need to stop heat entering the envelope of buildings isn’t being considered.
The Victorian Energy Saver Program states cool roofs are reflective surfaces designed to reflect more solar radiation and absorb less heat than a standard roof (Environment, Land, Water and Planning; State Government of Victoria, 2018). This reduction of energy in the form of BTUs into a building reduces the demand on energy consumption.
BTU is an acronym used worldwide which stands for British Thermal Unit as a form of measurement that measures energy. One BTU refers to the amount of energy that’s required to increase the temperature of a pound of water by 1°F. Although BTU itself is still a standard unit of measurement, most of the heating or air conditioning products in Australia are sold with kilowatt numbers instead of BTU. For example 9000 BTU = 2.6KW (currentforce.com.au, n.d.). BTUs are important because the heat gain through a roof increases the amount of BTU into a building. The more BTU from solar energy into a roof space the more KW used to keep cool. Therefore a white painted roof is better than a dark roof by 30% for reducing heat load and a heat block coated roof blocks the heat load which reduces energy consumption. An protected coated roof is even more efficient as it stops heat load.
Con Edison the New York electricity company supplies more than 10 million people in the New York area. It’s grid, with 62 power substations and more than 130,000 miles of power lines and cables across New York City and Westchester County, can deliver 13,400MW every second. This is roughly equivalent to 18m horsepower. It’s fair to say they understand the needs of energy consumption in major cities (Buranyi, 2019). There are net energy consumption gains as Con Edison research from New York stated “keep your thermostat set at 78°F (25.5°C) when your building is occupied…turning down the thermostat to 75°F (23.8°C) costs 18% more, and 72°F (22.2°C) costs 39% more!” (ARISTA Air Conditioning Corp, 2015).
White is the new black in roofs
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, 2017).
White and light design is the start. There are many articles worldwide stating why most aircraft are painted white. Finavia is a Finnish airport operator that enables international flight connections through its national airport network states the number one reason for white aircraft is it reflects sunlight. Other colours will absorb most of the light. This is crucial as when sunlight is absorbed by an aircraft, this heats up the body of an airplane. Painting a passenger plane white minimises both the heating and potential damage from solar radiation not only when the airplane is in flight, but also when it’s parked on the runway (Finavia, 2019).
The C40 Cities Climate report states “surface solutions are often readily deployable, simple, and cost-effective technologies available throughout the world. A cool roofing surface is both highly reflective and highly emissive to minimize the amount of light converted into heat and to maximize the amount of heat that is radiated away. Most existing roofs are dark and reflect no more than 20% of incoming sunlight, while a new white roof reflects about 70 to 80% of sunlight (sic not 70% of heat). Because of this, new white roofs are typically 28 to 36°C cooler than dark roofs, while aged white roofs are typically 20 to 28°C cooler. In addition to cost savings from reduced air conditioning, cool roofs also improve the life of the roof and performance of rooftop equipment, such as solar PV panels” (C40 Cities, 2016).
In Emily Caldman’s article Sydney’s New Suburbs Are Too Hot for People to Live In, “Australia is ahead of the curve when it comes to warming,” said Liz Hanna, an expert in heat and health at Australian National University. “We need to be really serious about not having houses where people sit and cook and die.” The Western Suburbs of Sydney for example, are a prime area for urban heat island effects (Cadman & Bloomberg Green, 2020).
Emily states “the more they build the worse it will get. As the volume of the hard surfaces increases, so does the temperature. Researchers found that in Sydney’s treeless urban areas, morning summer surface temperatures are nearly 13°C higher than in vegetated areas.
Most of the housing is built by the private sector and the homes are often single-glazed, black-roofed properties crammed together with little natural greenery. Access to shops or services nearly always requires getting into the car. On really hot days, the power grid can buckle under demand from air conditioners. “It is going to be stinking hot with lots of people,” said Pfautsch. “These new suburbs—the nice term is urban sprawl, I call them the Australian nightmare.” (Cadman & Bloomberg Green, 2020).
Examples of urban development and poor design are self evident in most Australian cities. While developers cram for maximum land value and maximum building space there is very little attention or regulation on sustainable housing and long term thinking. New ‘Baker’s Boxes’ are built with black cladding or roofing, substandard insulating, single glazing and air conditioners that drain power.
The Yale School of the Environment’s article, Urban Heat: Can White Roofs Help Cool World’s Warming Cities? states summers in the city can be extremely hot – several degrees hotter than in the surrounding countryside. But recent research indicates that it may not have to be that way.
The systematic replacement of dark surfaces with white could lower heat wave maximum temperatures by 2 degrees Celsius or more. And with climate change and continued urbanization set to intensify “urban heat islands,” the case for such aggressive local geoengineering to maintain our cool grows (Pearce & Yale School of the Environment, 2018).
So what’s a major barrier for advancing this next generation heat block coatings and reflective paints technology for the 21st century in Australia? Australia’s love for buildings with dark roofs and our sole fixation on traditional fibreglass insulation and R-values!
Moisture challenges with traditional insulation
It has proven to deteriorate with small amounts of moisture so gaining long term insulation efficiency benefits isn’t possible. As traditional insulation does little to address radiation and convection heat moving through the building or blocking radiant heat from being absorbed into a building’s envelope, there are the unknown costs of expansion and contraction of roof materials due to thermal shock. Thermal shock to roofs causes roof leak, corrosion and eventual roof replacements. The continual heat load, exposes traditional insulation to moisture or leaks, which renders it less effective therefore significantly deteriorating the R-value.
Wet insulation is a dilemma at the best of times, and glasswool insulation is no exception to this. It’s not difficult to understand why wet insulation doesn’t work, and will cause no end of trouble for the home owner if it is installed while wet. Firstly, glasswool relies on the microscopic airgaps inside – it’s the airgaps which are the actual insulators. Now if these get soaked with water, there goes your thermal insulation! Also, wet glasswool insulation will be susceptible to mould, and will introduce moisture to whatever area of the building it is installed, with potentially destructive results (Smith, 2019).
Edoardo Verduci’s article on insulation properties states “as the temperature increase or humidity level increase, the R-value of a product decreases, meaning it’s less effective at slowing down the transfer of heat. Real world situations can compromise the R-value of traditional insulation substantially (imagine that traditional insulation can lose 35% of its R-value when as little as 1.5% humidity is introduced).” (Verduci, 2019).
So if there is a leaky roof or condensation, chances are that the traditional insulation is no longer working properly, along with trapping moisture, fibreglass becomes a potential incubator for mould and fungus in the building. Each one of these problems independently causes a large drop in efficiency, but together they compound and magnify the problem. Air conditioners to run harder and longer combined with heat island effects from the local environment, therefore compounding CO₂ emissions…this is a huge future problem and solar heat block coatings are proving to be the new front line defence to our growing harsh environment.
Big changes to R-Values in Australia
Here’s a game changer, in Australia for the R-value materials under the Australian Standard AS/NZS 4859.1. The Standards outline the general criteria and technical provisions of thermal insulation materials for buildings. The updated standard will see changes introduced to the way the products are tested and how thermal performance (R-value) is calculated and declared, affecting bulk, reflective foil and rigid foam insulations. With the AS/NZS 4859.1:2018 introducing significant changes to product testing and labelling, the insulation market in Australia will see a change to product R-values being declared and advertised in data sheets. The new thermal testing requirements are more stringent, meaning that the declared product R-values will decrease across the insulation product offering (Kingspan Insulation Australia, 2020).
Lack of Australian standards – SRI isn’t the full answer
Australia seems to continue going down the unsustainable pathway unless governments and industry look at introducing new and holistic standards for solar heat block coatings and reflective paints as well as consideration of colours and design. The standard reflectivity and emissivity testing (Solar Reflective Index – SRI) has nothing much to do with heat load but more reflection of light and heat…not heat blocking. White paint is 70% reflective – in everyone’s mind, this would mean that 70% of the heat is reflected off the surface. If you believe this, then touch a white car bonnet on a hot day. It will burn your hand. If 70% of the heat was reflected, why is it hot? Because reflectivity of light has nothing to do fully with heat load.
Similarly emissivity only relates to how much heat was ever absorbed to start with on the surface then re-emitted. It is the equalisation of the loaded heat to releasing off the equal level of heat back to the atmosphere. Emissivity is based on a black box and it loads 100% of the heat and then throws off 100% of the equalised heat loaded. It does not mean it releases or blocks the absorbed heat in the surface, it only means it releases back the same amount of heat to the atmosphere that it loaded to equalise itself. The surface continues to hold all the heat it absorbed and transfers to the cool side. Many heat reflective paints promote they have a high SRI, which is true based on testing of reflectivity and emissivity, however there’s never been testing released on how much heat they’ve allowed to load in the first place. Heat load is critical! Super Therm® was consistently tested at 23°, 50°, 75° and 100° celsius with the results proving it blocked 99% of all the BTU heat load from the hot side to the cold side at all temperatures.
Emissivity of concrete is .94 which is higher than Super Therm® or many other white coatings. How is this? Because the surface is porous and can release the surface heat quickly back to the atmosphere. The density of the concrete has still absorbed the heat and is hot and will remain hot by holding the heat in its mass, yet it has a higher emissivity than most heat reflective paints.
So the basis of SRI testing with reflectivity and emissivity as the guideline of how well a coating controls heat doesn’t give the full facts about heat load and heat transfer. For heat control, be concerned about heat load and not just reflectivity of sunlight and emissivity which means nothing if the surface still loads much of the heat from the solar and thermal radiation. That’s also why many heat reflective paints work well while new, clean and white yet have proven once dirty can no longer perform to their original SRI testing results.
When high reflective paint is applied, it is important the ageing of performance should be considered. A study by Yasushi Kondo from Musashi Inst. of Tech. for the Tokyo Metropolitan Government, Japan Testing Center for Construction Materials in 2006 on 21 heat reflective paints showed even the most reflective paint lost it’s solar reflectance by 44% within 1.5 years. It was also noted, however there is no authorized standard for performance of high reflective paints in Japan. A standard or qualification system should be considered in Japan (Kondo, 2006) as it should be in Australia.
The true judge of “heat resistance” paints and coatings is testing that shows it’s performance in blocking and preventing the absorption of heat load, even when dirty. When you touch the bonnet of the white car or roof you’re not meant to burn and this shows the reduction of heat load into the density of the metal and the BTUs into the building, then you’ll truly know heat is not transferred. Currently there is no study underway for this new solar heat block technology in Australia. Nor is there testing beyond SRI to determine heat load. Measuring thermal emissivity is about out infrared heat leaving the substrate where it has loaded. Solar reflectance is about the 44% of heat reflected from the white paint. This leaves the 53% of heat in the infrared portion of the spectrum.
New solar heat block coatings and reflective paints need the same consumer standards which work for their own properties, technology and science beyond the SRI rating which doesn’t adequately cover the head load therefore true energy efficiency. The Australian and New Zealand Standards AS/NZS 4859.1:2002 state in the scope: 1.1 SCOPE: This Standard specifies requirements and methods of testing for materials that are added to, or incorporated in, opaque envelopes of buildings, to provide thermal insulation by moderating the flow of heat through these envelopes (Standards Australia & Standards New Zealand, 2002, p. 6).
C4 IN SITU EFFECTS: With reflective materials, the application (i.e. the method, location and environmental conditions of use) strongly affects thermal resistance, so that a single material may achieve many different thermal resistance values depending on the situation. Therefore, it is inappropriate to directly associate a single thermal resistance value with such a product (Standards Australia & Standards New Zealand, 2002, p. 34). In essence the standard says that R-value cannot be applied solely to reflective materials. While the Standards do acknowledge that ‘so that a single material may achieve many different thermal resistance values depending on the situation. Therefore, it is inappropriate to directly associate a single thermal resistance value with such a product’ it is appropriate that a new value system, such as ‘U-value’ or another that measures heat load be applied to solar heat block coatings and reflective paints that show more than reflecting light but true heat load resistance and heat transfer.
The ‘U’ value measures heat transfer and BTUs
As stated above, there are several challenges by relying on just the R-value as is just the SRI rating. Unlike R-values which measure ‘how fast’ heat moves; advanced heat block coatings and reflective paints could be rated on ‘how much’ thermal heat is being transferred through using ‘U’ values. The ASTM E 1269 and E1461-92 are Thermal Diffusivity or Heat Load Tests are more appropriate. Alternatively creating an industry measurement standard for thermal heat barrier coatings is important. For example, Super Therm® Solar Heat Block Coating was tested at E 1461-92 Thermal Diffusivity/Conductivity by Flash Method – TPRL BTU with a conduction of just 3.99 from 367.20 at 100°C – Blocking 99% of Heat BTU Conduction. The result was the same at 23°C, 40°C, 75°C and 100°C. This reduces heat load.
Unlike traditional insulation, the relevant temperature for the declared thermal values (23°C for Australia and 15°C for New Zealand) must be consistently applied across the relevant markets (Kingspan Insulation Australia, 2020). Yet as we’ve seen with the increase of forecasted Australian temperatures the measured value in a lab at 23°C doesn’t give ‘real world’ test results for traditional insulation materials. Testing could be rated at 25°C, 40°C, 75°C and 100°C.
The U-value assesses the rate of heat gain or loss through the total thicknesses of the combined elements that make up a building component such as a wall, floor or roof. It is measured in units of W/m2.K (Watts per metre squared Kelvin). It is a way of measuring the insulating properties of the building element. The lower the U-value, the better insulated the building element is. So a roof with a low U-value should prevent heat loss or gain better than a roof with a high U-value. Without knowing the U-value of a wall or floor or roof, you won’t know how energy efficient the whole building will be (Kingspan Group, 2017). Measuring SRI doesn’t give you any facts regarding energy efficiency which is similar to R-values.
NBS based in the UK is a global leading technology platform that combines high quality content and connectivity for anyone involved in the design, supply and construction of the built environment, they state that “although the main focus of environmental performance of buildings is now on carbon usage, there is still a need to consider thermal performance of the building fabric as a contributing factor. Thermal performance is measured in terms of heat loss and gain (sic)”. Thermal insulance is the converse of thermal transmittance; in other words, the ability of a material to resist heat flow. R-values are more commonly used in certain parts of the world (for example Australasia), in contrast to the UK’s preference for U-values (Lymath & NBS, 2015). It makes complete sense to rate insulation on thermal insulance to better understand and measure the carbon usage, effectiveness of insulation and value of the investment.
The cool global changes in cool roofs
Currently Australia doesn’t consider measuring thermal heat transfer as important nor is there any leadership or investment in this space. This is a definite blindspot in our future and sustainable building model testing standards in Australia and carbon emission reduction. How much heat is being transferred? In reality, there are three sources of heat; conduction, convection and radiation, therefore there is a need to measure the thermal heat transfer through materials which are converted to infrared heat or conduction. U-values at least represent the transfer of heat energy from all three heat sources combined with the substrate and defines which coatings and paints actually work as well as for how long.
Given the Kondo study from Japan which showed a 44% loss in 1.5 years, longevity is critical which Super Therm® offers for 20 years. The successful measurement of all insulation needs to evolve from one dimensional and traditional style R-value to more advanced measures adapting to a changing environment, recordings, materials and insulation technologies.
A report by the Natural Resources Defense Council and partners in India, roofs offer an avenue to significantly impact internal temperatures and provide indoor thermal comfort, in both air-conditioned and non-air-conditioned buildings. Cool roofs, with their specific characteristics, are better at reflecting solar radiation and emitting absorbed heat. Depending on the setting, these cool roofs can help keep indoor temperatures lower by 2 to 5°C (3.6 – 9°F) as compared to traditional roofs, offering simple and effective protection from extreme heat especially for vulnerable communities in low-income housing.
Cities can lead the way in cool roof implementation. In 2017 and 2018, the cities of Ahmedabad and Hyderabad in India, initiated pilot cool roof programs. These initial programs include citizen awareness campaigns, pilot initiatives targeting 3,000 roofs, cooperation with businesses, and applying cool roof techniques to government buildings and schools (Natural Resources Defense Council – India, 2018).
The 2013 NCCARF report A Framework for Adaption of Australian Households to heatwaves, recommended modifying roofs by increasing solar reflectance, adding reflective foils and increasing thermal insulation. While traditional insulation slows the heat load stopping the solar energy at the roof is the key.
The report says “The amount of solar energy which the roof absorbs is strongly dependent on the reflectivity of solar radiation from the roof which is related to the roof colour. In southern Australia, the most popular roof colours for new houses for the last decade have been dark, with light-coloured roofs being least popular. In locations such as Brisbane and Darwin, light-coloured roofs have traditionally dominated; however, there is a concerning trend of dark-coloured roofs being used in some new homes. The amount of solar energy absorbed by the roof is a significant factor which determines the heat transmission into the dwelling during heat waves. The absorbed radiation is a function of the total solar reflectance (TSR) of the roof, which is the ratio of the reflected solar radiation to the total radiation incident on a surface. The range over which measurement is made is generally between either 280 or 300 nm and 2500 nm. A typical grey- or black-coloured roof has a TSR of around 0.05 to 0.1, and a white roof has a TSR of around 0.9. Overall, the defining parameter which determines the temperature rise of the roof surface compared to the ambient temperature is not the colour but the specified TSR.
Roof surfaces which absorb high amounts of solar radiation can readily reach temperatures of 80°C in hot weather. This temperature represents the driving force of the heat flow into the building. Roof surfaces which absorb low amounts of radiation can dramatically reduce this temperature, bringing it closer to the ambient temperature” (NCCARF, 2013).
Organisations around the world acknowledge the need for cool roofs, Australian and New Zealand Standards acknowledge reflective paints as a part of the solution for urban heat island effects and new solar heat block coating technologies such as Super Therm® have proven it allows must 5% of heat to load creating energy savings, reduced CO₂ emissions, personal comfort and asset protection while supporting traditional fibreglass insulation for 20 years. This therefore debunks the belief that R-values are the only method of measuring insulation to resist heat flow when there are modern and advanced methods. It also questions the ratings from SRI as a true measure of heat load and heat transfer. ‘U’ values and heat transfer measurements such as TSR dramatically improve the overall and ongoing investment of protection for the 21st century.
Action needs to start!
As a majority of houses in Australia have dark roofs this magnifies the heat load by another 25-30% increasing a 40°C day inside a roof to potentially over 80°C+. Even a 25°C day will raise the temperature in the roof space to 40°C. Air conditioning ducts are in the roof space with the extra heat load and struggling to keep air cool. Air conditioners are forced to work extremely hard, consuming more power and costing more to run and putting more pressure on the nation’s energy supply grid and CO₂ emissions.
Research from the UniSA by Dr. John Pockett on Cool Roofs and Heat Reflective Paints states the cooling efficiency for air conditioners is about half their maximum capacity on very hot days. This requires much more electricity to get the same cooling effect and is one of the reasons why our modelling shows more effective for light rather than dark roofs compared with modelling based only on the first step, heat flow into conditioned spaces (Pockett, n.d.).
Simple logic would also lead us to acknowledge that the R-value formula can only begin once the heat has loaded, but stopping extra heat from being absorbed by reflecting it back helps reduce the urban heat island, save energy and improve comfort. A double pronged approach means traditional insulation can work with proven new technology solar heat block coatings because it doesn’t have to carry the full heat load it was not designed for, yet when complimented by a truly advanced and proven solar heat block coating like Super Therm® that prevents thermal heat transfer, creating a truly innovative sustainable 21st century solar heat management solution.
To summarize our current challenges
- R-value measures conduction heat only and doesn’t stop heat
- U-value measures total thermal transfer
- Government acknowledge heat absorption through roofs is 25-35%
- No mention in Australian building codes about stopping heat entering building envelope
- Reflective coatings are acknowledge in Australian and New Zealand Standards
- Air conditioners have to work very hard to keep buildings cool
- Large international focus on the impact urban heat island effects
- Dark roofs absorb more than 70% of heat compared to white roofs
- Energy prices are rising and Australia has 4 states in the top 10 for energy prices globally
- Global warming is seeing a rise in extreme heat days
- Building codes don’t focus on heat resilience
- Cool Road programs internationally have a similar principle as Cool Roofs
- UK becoming leaders in U-value modelling
- SRI doesn’t measure heat load into the substrate where the heat is transferred
- Tests in Japan show reflective paints can decrease by 44% within 1.5 years
With the problems identified above, the solution could be simple:
- Stop heat load
- Stop moisture
- Standards for solar heat coatings and reflective paints
Traditional insulation struggles in the extreme environmental heat conditions to do this. The only products designed to withstand the dramatically changing environment are proven thermal coatings, which block the heat load, stop moisture and air penetration and effectively seal the building envelope keeping it just above ambient temperature.
The master of ceramics and heat management
Joseph E. Pritchett (J.E.) is a Ceramic researcher and formulator from Superior Products International II, Inc. USA holding a Bachelor of Science from University of Arkansas and Paint Technology courses from University of Missouri. Graduate studies performed with NASA in Huntsville, Alabama, USA and Ceramic Materials research over the past 30+ years. He has studied more than 7,000 ceramic compounds to determine the type, crystalline structure and size to perform most efficiently for different heat needs (US Green Building Council, n.d.). He is a world authority and researcher on ceramics and heat block coatings.
Understanding the principle of emissivity is critical to getting your head around the science and difference in reflective paints compared with solar heat block coatings. The National Physical Laboratory, UK state emissivity is defined as the ratio of the energy radiated from a material’s surface to that radiated from a perfect emitter, known as a blackbody, at the same temperature and wavelength and under the same viewing conditions. It is the measure of an object’s ability to emit infrared energy. Emitted energy indicates the temperature of the object. Emissivity can have a value from 0 (shiny mirror) to 1.0 (blackbody) (National Physical Laboratory, UK, n.d.).
J.E. explains how emissivity is the ability to throw heat off the surface of the coating and not to load heat into the coating therefore loading the substrate below. If white was the only answer to blocking heat load and conduction, then touching any white car hood would feel cool – it does not, and loads much of the heat that radiates to it, therefore, just because it is white does not mean it will reflect all the heat and protect. White is better than other colours to begin the initial effort to not absorb heat, but alone, it is not the answer. It still reflects better than a black car but still contains infrared heat. A piece of paper when you touch it is warm but it doesn’t have the density to hold the heat. Super Therm® contains scientifically formulated ceramic compounds that are designed to reflect the sun’s 3 solar heat energy forms and another compound that acts as a block to emissivity and is 50 times lighter than paper which continually throws the heat off…therefore stopping heat from passing through (NEOtech Coatings Australia, 2020).
SPI has researched, developed and tested proven solutions to the real-world problems related to heat and corrosion (Superior Products International II, Inc., n.d.). It holds the distinction of having scientific research and industry testing relationships with major corporations from around the world, including NASA. SPI worked with NASA for 6 years on the development of Super Therm®.
Super Therm® is produced by the USA Superior Products International (SPI), it is a tried-and-tested eco friendly coating that has over a 30 year proven record and has been tested to reflect 95% of the sun’s heat. Super Therm® is designed to keep your building and roof cool by reflecting heat and stopping moisture and air flow passively with proven heat protection benefits…even when dirty. This dramatically minimises UHI effects.
As a simple trial, Barakat Quality Plus, a leading juice producer in Dubai has completed “Super Therm® coating trials on its refrigerated truck trailer roof. “Super Therm® will dramatically improve heat protection performance, extending the useful life, and increasing the effectiveness of the trailer, stock and fuel efficiency. It helps to keep the refrigerated trailer on the road, generating revenue by maintaining excess cooling capacity, decreasing unit maintenance downtime, and expanding its productivity. Super Therm® is Energy Star qualified as a 20-year roof coating” in a 21st century world (Gulf Construction, 2011).
Air conditioning is costing Australia more than $1.3 billion over the summer months, according to new research (News.com.au, 2017). Buildings consume 39% of all energy in the economy (Frank Chung, 2016). In summer, keep your thermostat set at 25°C when your building is occupied. According to ConEd, turning it down to 23°C (75°F) costs 18% more, and 22°C (72°F) costs 39 percent more! (Rosone & ARISTA, 2015)
Without doubt there is significant international scientific government data and industry testing on the major benefits of cool roofs for the long term fight against carbon emissions and global warming. There does need to be a shift in the mindset of the definition of ‘insulation’ and heat resilience from both industry, government and community to really capitalise on the blindspot opportunity that will drive transformation in our society. Genuine and proven solar heat block coatings that reflect as much of the heat solar energy as possible will go a long way to helping the world battle the future issues of rising energy costs, rising global temperatures and personal comfort. Embracing the next generation of heat block coatings that compliments the traditional insulation industry will ensure we have a two pronged approach and better solutions for decades to come.
- Heat Load & SRI Infographic
- Urban Heat Island effect and Cool Roofs Video
- Department of Energy USA – Testing Results 20-50% energy savings
- About Super Therm Ceramic Insulation Coating
Shane Strudwick is Managing Director of NEOtech Coatings Australia, a provider of specialised high performance and technologically advanced coatings for government, industry and private projects. NEOtech are Australia’s sole SPI Coatings USA Distributors. Further information about NEOtech Coatings Australia or Shane can be obtained from the website neotechcoatings.com or Linked In.
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