Investigating energy saving potential of switching solar absorptance coatings onbuildings

Student thesis: Master

Abstract

The rising awareness of the downsides to mass-energy consumption and strict regulations have forced the building sector to develop innovative building envelopes to increase energy efficiency. This research investigates the potential of applying thermochromic solar control coatings on the façade and roof of buildings to reduce the total heating and cooling demand in comparison with various static coatings. An application-centric approach is applied to determine the optimum coating properties including transition temperature, low and high solar absorptance values for an array of building and climate scenarios. The work concludes that these optimum properties are dependent on the intrinsic heating and cooling demand ratio of each application, which is influenced by climates, insulations levels, and building types. It was observed that static solar control coatings tuned to either absorb or reflect solar heat gains deliver higher energy savings in applications with unilateral energy demand. Low insulation terraced houses in the Netherlands with high heating demands can attain annual cost savings of up to 4.3 €/m2 of floor space when a low (0.0) solar absorptance coating is replaced with a high solar absorptance (1.0) coating on the façade and roof. Thermochromic coatings applied to these applications incur energy penalties caused by false switching, which are switching between solar absorptance states which are not representative of the building’s energy demand. However, thermochromic coatings offer higher energy savings in applications with heating and cooling demand of similar magnitudes. In these applications, thermochromic coatings cumulate energy savings from both the heating and cooling demand fields which are higher than energy savings captured by static coatings. The cost saving of thermochromic coatings increase as the solar absorptance gap between the two states is increased. Thermochromic coatings with 40% switching between solar absorptance states can at average capture 60% of the total cost savings. Replacing optimal static coatings with thermochromic coatings with 40% switching in low insulation terraced house results in annual cost savings ranging from 0.84 €/m2 (Spain) to 0.6 €/m2 (Italy) of floor space. These cost savings decrease with higher insulation in building envelops but are marginally influenced by the building’s thermal mass. As thermochromic coatings are an emerging technology the initial cost of implementation is high, which results in long payback periods. However, with further development, thermochromic coatings show promise in reducing the energy consumption of buildings with low insulation in regions with high seasonal fluctuations. Finally, the methodology inscribed in this research can be employed to determine the optimum solar control coatings for additional building and climate scenarios.
Date of Award20 Aug 2019
Original languageEnglish

Keywords

  • Thermochromic Coatings
  • Building Performance
  • Energy Saving

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