building physics

BUILDING PHYSICS 27 Summer heat insulation Summer heat insulation (heat protection) helps limit the heat that is created in the interior of the building through the direct or indirect irradiation of the sun, which is usually largely due to irradiation through the windows, to a bearable measure. This is done primarily by minimising the heat addition from the direct irradiation of the sun, reducing the heat conductivity of wall, roof and ceiling surfaces, and the waste heat of electrical devices and people. Windows without protection from the sun have the biggest effect on the heating of interior rooms. Summer heat insulation is becoming more and more important, in particular in consequence of global climatic change and the trend toward rising temperatures. This is related to the increasing use of air conditioners, which in turn lead to climbing power and respectively energy consumption, and thereby also to increasing CO2 emissions especially in the summer months. This is why summer heat insulation has to be considered already in the building planning phase to avoid that buildings overheat during the summer resulting in uncomfortable room temperatures. In residential buildings room temperatures in an average summer will remain below 27 °C due to nightly ventilation, low heat dissipation of devices, sun shading and heat storage. During heat waves, they are likely to rise somewhat. In offices, temperatures of below 26 °C are aimed for. In this regard, it is particularly important to pay attention, on the one hand, to corresponding sun shading devices that are installed on the outside of the windows, so that the “glasshouse effect” can be prevented and, on the other hand, to especially understanding and considering the summer behaviour of buildings and that of the users. Not only the occurring maximum temperature but also the period during which a certain temperature threshold is exceeded is significant for the user’s subjective perception. The effect of the user behaviour on summerly room temperatures in consideration of various building materials or construction methods applied – light-weight construction, brick construction, concrete construction – has been analysed by measurements in occupied properties within the scope of a research project. Parameters that influence the behaviour of not actively climate-controlled buildings during the summer or the room heating in consequence of summerly irradiation of heat are: • the outdoor climate • the thermal properties of the used components in the exterior area such as surface paint, heat insulation capacity, component assemblies or layer sequence, the capacity to store heat especially of components located on the inside, the overall degree of energy permeation, the size and orientation of the used glazing, existing sun shielding systems and their effects • orientation of the exterior wall surfaces • use of possibilities for night-time ventilation and the sun shielding equipment • release of heat from electrical devices, illumination and people • storage efficiency of items of furniture and structural design The results of the research project show that regardless of the construction method, the building materials used, and the existing thermal storage of the mass in the interior room, it is the user behaviour and foremost incorrect use of ventilation possibilities that has a greater effect on the progression of summer room temperatures. At the same time, the nightly dissipation of heat through windows is decisive for the summertime thermal behaviour of rooms. Ensuring comfort in the living rooms (see Figure 14) during frequently occurring heat periods is a central concern of Saint-Gobain Multikomfort. The aim is to reduce temperature peaks in the summer and increase comfort in the room. The Rigips Alba®balance full-gypsum boards developed for this purpose absorb the room heat that exceeds the comfort zone and release it again when there is sufficient nightly ventilation. Figure 14 – Well-being in the interior space

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