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The influence of surface finishes on the energy demand of HVAC systems for existing buildings.

Number: pap. DEC-05

Author(s) : MARINO C., MINICHIELLO F., BAHNFLETH W.

Summary

This research aims to apply techniques of passive climate control to existing buildings, in order to obtain relevant energy saving by using innovative surface finishes. The related energy influence is evaluated in both heating and cooling seasons, considering
typical HVAC systems. First of all, considering the Italian case, the Report “SAIE Energia 2011” identified the potential market for improving the energy efficiency of the existing residential building stock. In particular, from this Report, it seems appropriate to take action, over the next 15 years, on the thermal-physical properties of pitched roofs (areas between 397 and 423 million square meters); indeed, these building envelope components are today quite neglected during the energy retrofit actions. In temperate climates, to reduce the energy operating costs associated to the summer air conditioning, in the case of flat roofs it is common to use the white roof; the problem occurs in the cases of retrofitting of typical buildings in historical centres, characterized by attics (pitched roof). They are born with not residential functions and present wooden structures with low thermal inertia, not insulated, coated with brick tiles with a very low solar reflectance (less than 0,3-0,4). These attics are characterized by high values of heating and cooling thermal loads. The present paper intends to carry out an analysis of an architecturally-compatible energy retrofit measure, preserving the monolithic and chromatic characteristics of components. This refurbishment can also extend the useful life of the structures, reducing thermal shock and condensation. Also a technical economic evaluation is performed. All the analyses are carried out using a dynamic energy simulation code, with appropriate modelling of typical attics in Italy and in various European climates (floor area of about 100 m2), considering heating/cooling systems commonly used in residential constructions. The proposed refurbishment consists in applying, on the outer surface of the building envelope (pitched roof), special coatings in multimineral paint of red tile colour. This coating (“cool paint” or “cool colour”) is characterized by the same spectral response of the traditional tile in the visible range, but high values of solar reflection factor (0,79), infrared emissivity (0,89) and Solar Reflectance Index (99). In particular, in summer conditions, it is possible to reduce the building envelope thermal energy needs up to 60%, by applying the described paint. In winter conditions, the thermal needs can be reduced up to 12,5%, by applying a low infrared emissivity coating (0,62) on the internal surfaces of the building envelope. This coating is obtained by mixing a traditional plaster with ceramic nanospheres. The described energy efficiency measures are simple and cheap. Depending on the climate zone, a discounted payback time of few years can be achieved for both warm and cold European regions. Therefore, the use of suitable surface finishes significantly reduces the energy demand for heating and cooling in existing buildings.

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Pages: 20 p.

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Details

  • Original title: The influence of surface finishes on the energy demand of HVAC systems for existing buildings.
  • Record ID : 30012158
  • Languages: English
  • Source: 49th AiCARR International Conference. Historical and existing buildings: designing the retrofit. An overview from energy performances to indoor air quality.
  • Publication date: 2014/02

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