Research

The Influence of Energy Renovation on the Change of Indoor Temperature and Energy Use

TalTech, Estonia, 2018

The aim of the renovation of apartment buildings is to lower the energy consumption of those buildings, mainly the heating energy consumption. There are few analyses regarding those other energy consumptions which are also related to the primary energy need for calculating the energy efficiency class, including the primary energy need of calculated heating, domestic hot water (DHW), and household electricity. Indoor temperature is directly connected with heating energy consumption, but it is not known yet how much it will change after renovation. One of the research issues relates to the change of electricity and DHW usage after renovation and to the question of whether this change is related to the users’ behavior or to changes to technical solutions. Thirty-five renovated apartment buildings have been analyzed in this study, where the data of indoor temperature, airflow, and energy consumption for DHW with and without circulation and electricity use in apartments and common rooms has been measured. During research, it turned out that the usage of DHW without circulation and the usage of household electricity do not change after renovation. Yet there is a major increase in indoor temperature and DHW energy use in buildings that did not have circulation before the renovation. In addition, a small increase in the use of electricity in common areas was discovered. This study will offer changes in calculations for the energy efficiency number.

Doctoral thesis proposes solutions of rainwater usage for domestic hot water production in buildings

TalTech, Estonia, 12.06.18

The PhD thesis proposed a solution for using stormwater thermal energy. The comparison of three types of buildings – a shopping centre, an office building and an apartment building – indicated that an underground stormwater storage tank is an optimal solution for a shopping centre, since it has the best conditions for the rainwater harvesting and hot-water consumption. Thus, the PhD thesis provides a novel solution for utilization of stormwater as a low-temperature water thermal energy source for buildings, as well as for cooling of buildings, if necessary.
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Engineers: In nearly zero energy buildings in Estonia, special attention must be paid to window design

TalTech, Estonia, 29.05.18

The studies of the insolation, i.e. direct solar access to premises, indicate that the current requirements set for the minimum insolation hours (at least 2.5 hours of uninterrupted sunshine to the premises) are not justified in designing modern nZEBs. The research demonstrated that following these requirements increases the risk of overheating. The requirements should be based on daylight factor values (insolation characterises direct solar radiation, whereas a daylight factor characterises diffuse radiation, i.e. cloudy weather).
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Retrofit cost-effectiveness: Estonian apartment buildings

TalTech, Estonia, 2016

The economic viability and investment cost of the energy retrofit of apartment buildings are analysed through different energy efficiency levels. To analyse retrofit policy cost-optimal energy efficiency levels and investment costs, a baseline of measured actual energy usage of apartment buildings was created and then individual energy-saving measures and retrofit packages were composed. The cost-optimal level over a 20-year period for apartment building retrofit was a low-energy-building energy performance level, with an investment cost of €150–170/m2. Retrofit to low energy building level would be economically viable but the investment capability of apartment owner associations is found to be insufficient for the necessary investments to achieve low-energy-building energy performance. Therefore, it is necessary to determine what levels of financial support can encourage retrofit to occur. The analysis of the current retrofit shows that subsides will increase investment by apartment owner associations into energy efficiency improvements. The target group for energy efficiency retrofit subsidies should be apartment buildings that reach low energy building performance level or at least match the energy performance requirement for new buildings.
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