Advantages of cool roofs

There are several advantages to producing a cool roof:

  • Improved ambient conditions inside the building during summer months
  • Less energy required for air-conditioning to cool rooms inside the building in summer
  • Improved energy efficiency of the whole building envelope
  • Reduced heat island effect (the term heat island is used to describe the phenomenon whereby the temperature generated in urban areas is higher than that recorded in rural areas)
  • Greater dimensional stability of roof build-up system and underlying load-bearing structures as the effect of high summer temperatures is mitigated (less movement, expansion, cracking, etc.)
  • Longer service life expectancy of waterproofing roofing membranes as the low surface temperature greatly reduces the natural heat-induced aging process.

What is thermal emissivity?

Thermal emissivity is a measure of the ability of a material/surface to disperse heat. A surface with a high thermal emissivity rating has the property of effectively radiating heat to the surrounding environment. Polymer waterproofing membranes (PVC-P and TPO/FPO), MBDP polymer distilled bitumen membranes and protective coatings for MBDP membranes all have high thermal emissivity. Emissivity is rated from 0 to 1 or as a %.

According to Italian law (D.M. 26.06.2015)

Ministerial Decree (D.M.) 26.06.2015 is the legislative instrument on building energy efficiency currently in effect in Italy and has been supplemented with content concerning how buildings behave in summer. Appendix 1 to the decree expressly indicates: "3. In order to limit energy requirements for air-conditioning in summer and keep indoor temperature down, and to limit overheating in urban areas, the use of certain systems in building roofing structures must be checked for efficiency in terms of cost-benefit ratio, more specifically: a) cool roofing materials, to have a solar reflectance rating of at least: - 0.65 in the case of flat roofs; - 0.30 in the case of pitched roofs; b) passive HVAC technologies (including by way of example, but not limited to, ventilation, green roofs). The above-mentioned checks and assessments are to be documented in a technical report as explained in section 2.2."