This research and associated fact sheet has been commissioned by the City of Melbourne to provide direction to consumers about the use of “Cool” or “White” roof paints (hereafter referred to as Cool Roof Paint (CRP), that have a significant higher reflectivity and emissivity when compared with normal roof materials and coatings. The report includes field testing of a variety of cool roof technologies, a literature review of cool roofs research, product descriptions, and a simulation of impacts on Melbourne.
For a typical residential building, the simulation showed that a standard attic space temperature profile would vary greatly based on the location of the insulation. If the insulation is located on the ceiling (below roof space – as is the case with most residential buildings at this time) the attic space would be up to 18.5 degrees cooler with the use of CRP. If the insulation is located under the roof (above the roof space) the CRP’s have only a minor impact on the temperature of the roof space.
When extending the computer simulation of the CRP’s to a typical commercial and industrial building, again the importance of ceiling insulation to the results became apparent. It was demonstrated that a commercial building in Melbourne could benefit by approximately 3% in terms of cooling energy reductions – it is expected that much higher savings would be achieved depending on the building age, construction and location, as found in the literature review. This result suggests that many older office style buildings would benefit from the use of these products.
Uninsulated, un-conditioned industrial buildings also can benefit from these products, with the results showing that depending on the internal temperature load, a significant reduction in indoor temperature can be achieved. Conversely, in an industrial building that has a low internal gain profile, such as a warehouse or similar, the products had the effect of improving the comfort (indoor temperature) in the summer months and reducing the comfort in the winter months, leading to a net zero benefit.
It is clear from the results of this study that buildings with high cooling loads and minimal insulation will received significant benefits with the use of CRP’s. Buildings without a significant cooling load, and with typical insulation levels (e.g. residential buildings) can benefit from these products, but will be sensitive to roof pitch, shading and of course the level of ceiling insulation.
Publication Date: September 2011