Kalle Kuusk

Retrofit cost-effectiveness: Estonian apartment buildings

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.

Impact of linear thermal bridges on thermal transmittance of renovated apartment buildings

AbstractRenovation of old apartment buildings is a topic of current research interest throughout the Eastern Europe region where similar typology is derived from the period of 1960–1990. Thermal bridges, essential components of the transmission heat loss of a building, have to be properly evaluated in the energy audit during current state-of-the-art situation as well as in the comparison of renovation solutions. Resulting from field measurements and calculations, we propose linear thermal transmittances Ψ of thermal bridges for four types of apartment buildings: prefabricated concrete large panel element, brick, wood (log), and autoclaved aerated concrete. Our results show that thermal bridges contribute 23% of the total transmission heat loss of a building envelope before renovation. After renovation thermal bridges account for only 10% if windows are repositioned into additional external thermal insulation and balconies are rebuilt as best practice. Inversely, impact of the thermal bridges might be up t...

Case-study analysis of concrete large-panel apartment building at pre- and post low-budget energy-renovation

AbstractThe paper presents a case study analysis of low-budget renovation of a typical concrete large-panel apartment building. Focus is on the measurements and analyses of energy consumption, indoor climate, CO2 concentration, air leakage rate, thermal transmittance of thermal bridges, and thermal transmittance of the building envelope before and after the renovation. Results indicate that the renovation project was generally successful, with delivered energy need decreasing by 40% and heating energy need decreasing by 50%. However, some key problems need to be solved to achieve full energy efficiency potential of the renovation works. Those critical problems are the performance (thermal comfort, heat recovery) of ventilation systems, thermal bridges of external wall/window jamb and economic viability. Currently, a major renovation is not economically viable, therefore financial assistance to the apartment owners’ associations is required to encourage them to undertake major renovations.

nZEB Renovation of Multi-Storey Building with Prefabricated Modular Panels

Reduction of energy use in buildings in EU is expected to be reached with help of fulfilling of requirements of low and nearly-zero energy buildings (nZEB) policy. The efficient way to accomplish the purpose of the nZEB is to apply the integrated design process, considering the long-term sustainability and building costs as a one setup. The multi-storey large concrete element building is renovated to nZEB as a Horizon2020 MORE-CONNECT project pilot in Tallinn. The study of that project includes complex of measures: hygrothermal measurements and analysis, highly insulated facade and roof elements, the full modernisation of heating and ventilation systems. Ventilation ducts are installed into the modular panels to minimize supply ductworks in apartments. Roof panels include solar panels and collectors for renewable energy production. All technical systems will be equipped with monitoring systems and data will be logged periodically. The designed thermal transmittance is U≤0.11W/m2K for walls, U≤0.10W/m2K for roof and U≤0.80W/m2K for windows and external doors. The analyse, design and renovation process of the integrated nZEB design method gave us a unique experience, showing weak links in the chain and helping to prevent faults in the whole process in the future.

Experimental validation of simulation and measurement-based overheating assessment approaches for residential buildings

ABSTRACT As a part of the building design process, Estonian building code requires standardized dynamic hourly simulations to verify the building’s compliance to the summer thermal comfort requirements. In this study, we analysed this overheating assessment method for free-running residential buildings, by comparing the simulation results with measured data. Simulation models with different thermal zoning levels were studied: single-zone models, multi-zone apartment models and multi-zone whole building models. We analysed and quantified the effects of modelling detail and thermal zoning on indoor temperature and overheating estimation on the basis of five apartment buildings. Based on the results, a method, using indoor temperature measurements and outdoor climate data, to assess overheating risk has been proposed, as a relatively simple and inexpensive method for pre-defining the need for dynamic simulations.

Cost-Effective Energy and Indoor Climate Renovation of Estonian Residential Buildings

Renovation of the existing residential building stock is a key factor in the future of building energy savings in Estonia, as the replacement rate of existing stock is only 1–2% per year. This research analyses the energy-efficiency and economic viability of the energy renovation of dwellings. Individual energy-saving measures and renovation packages were composed for reference buildings to analyze cost-optimal energy-efficiency levels. The research uses the methods of large-scale field studies as well as computer simulations to analyze the energy performance of dwellings in Estonia.