Members Area
report u values

4. Insulation and cooling

The Ecofys report “Mitigation of CO2 Emissions from the Building Stock – Beyond the EU Directive on the Energy Performance of Buildings” showed in an excursus, that insulation can, besides saving energy in the heating period, also save cooling energy in southern climates during summer. To assess the effects of added insulation on cooling demand in hot climates and the resulting influence on cost-efficiency of insulation measures, calculations have been performed with the thermal simulation programme TRNSYS.

In a first step, calculations have been performed for southern Europe for a standard terrace house (attached building) and multifamily house with typically high mass, average internal gains, external shading, natural ventilation, to cover the assumed average situation of a single building in southern Europe which already applies reasonable passive cooling strategies. The geometries have been adopted from the standard houses used in previous Ecofys reports (Ecofys II to VI). The starting point for the assessment of influence on cooling energy demand from added insulation is described in the following:

Reference buildings:

  • Single family house (SFH): Terrace house with 120 m2 usable floor area

  • Multi family house (MFH): Building block with 1.600 m2 usable floor area

Both reference buildings were assumed to have the following characteristics:

  • Building materials: brick walls, concrete roof deck and floors, roof with light coloured covering

  • Internal gains: 3 W/m2

  • External shading of windows (75%)

  • Natural ventilation

    • Average air-exchange rate day: 0,65 (infiltration and ventilation via windows)

    • air exchange rate night 2,5

  • active cooling via air-conditioning system, maximum comfort temperature to keep: 25 °C

  • Initial starting point: no insulation applied

In order to study the effect of insulation, internal heat gains and shadowing on the cooling demand to keep the comfort conditions in the reference buildings, the following “package of measures” was applied:

  • wall: U-value reduced from 1,7 to 0,6 W/m2K

  • roof: U-value reduced from 2,25 to 0,5 W/m2K

  • floor: U-value reduced from 1,0 to 0,5 W/m2K