Thermal insulation of buildings and cooling demand

Thermal insulation in the warm climate can reduce the energy demand for cooling in residential buildings up to 70%.To define the gap in between the actual applied thermal requirements and what would be todays economic optimum,Eurima ordered a study to Ecofys which also quantified the impact of thermal insulation in reducing the cooling demand in residential buildings. A standard row house and multifamily house with relative high thermalmass, average internal gains, external shading, naturalventilation, which already applies reasonable passive cooling strategies, was taken to cover the assumed averagesituation of a single building in southern Europe.The results show that substantial savings of cooling energydemand can be realised by adding insulation. At the same time it is visible that the total demand for cooling energy is significantly decreasing from very hot climates like Sevilla with 908 cooling degree days to less hot climates like Marseille with 427 cooling degree days.The effect of the single measures of insulating the externalwalls, roof or ground floor is quantified. Remarkable is the positive effect of roof insulation. This is caused by the especially high temperatures of the roof due to the effect of solar irradiation with according benefits of thermal insulation of this surface. At the same time, the insulation of the floor results in an increase of coolingdemand, because the cooling effect of the (cooler) ground is reduced.In a second step a sensitivity analysis was carried out to assess the influence of different situations concerning external shading, internal gains, ventilation strategy and thermal mass on the changing cooling demand if insulationmeasures are applied.When looking at the total energy demand for cooling, it is in the first place visible that passive cooling strategies like high building mass, external shading, night ventilationand reduction of internal heat loads are effective measures to decrease cooling energy demand.At the same time, adding insulation leads to a reduction of cooling energy demand. This seems to be especially the case for low mass buildings where added insulation can to a large extend replace the thermal inertia of a massive building.It can be stated, that the influence of insulation on coolingdemand is relatively constant in different situations with the exception of technical premises like buildings with low mass (leading to significantly larger saving potential)and buildings with no external shading equipment(reducing the savings potential).The study also leads to the conclusion, that the benefit of insulation regarding cooling is quite robust against misbehaviour of tenants who might have higher internalgains or who do not use ventilation strategies such as night ventilation.