EVALUATION OF THERMAL LOSSES IN A CONTEMPORARY MULTI-STOREY RESIDENTIAL BUILDING WITH A WARM ATTIC

Abstract

The article presents the results of an experimental study of ventilation heat losses in a multi-apartment residential building with a warm attic. The relevance of the work is determined by the priorities of the State Program “Sustainable Energy and Energy Efficiency” for 2026–2030 in the Republic of Belarus, where one of the key areas remains the improvement of energy efficiency in the housing and utilities sector. Multi-apartment buildings from the period of mass industrial construction are characterized by increased heat losses, including through the natural ventilation system, the share of which in the total heat energy consumption for heating can be significant. Particular attention is paid to buildings with a warm attic, which allows combining exhaust ducts and reducing heat losses through the roof. However, design calculations often rely on normative values of air exchange rate and design temperatures, which do not always reflect real operating conditions, especially during transitional periods of the heating season.

The purpose of the study is to obtain objective experimental data on the magnitude of ventilation heat losses and to assess their share in the overall energy balance of the building. The work involved full-scale measurements on a real 9-storey brick residential building in Brest (heated area 2762,1 m²) with natural ventilation, where individual exhaust ducts from apartments are combined into common shafts leading into the volume of the warm attic. The study covered the period from March 10 to March 20, 2026 (11 days of the transitional period). The temperature of the exhaust air in the ventilation shafts and the common exhaust shaft of the warm attic was measured using Thermochron iButton loggers, along with heat energy consumption according to the commercial heat meter and outdoor air temperature. Calculations of the normative air exchange for apartments were performed, domestic heat gains were determined based on hot water consumption, and specific energy consumption indicators were assessed using normative methods and thermal balance formulas.

It was established that the average temperature of the exhaust air from the common shafts is about 23,2 °C, which is significantly higher than the design value of 18 °C. A significant share of ventilation heat losses in the building’s energy balance has been experimentally confirmed. A substantial excess of the actual specific heat energy consumption for heating and ventilation compared to the design values has been shown. Features of the warm attic system operation were identified, including occasional stack effect reversal. The work emphasizes the prospects of improving ventilation systems, including the use of heat recovery from exhaust air, to increase the energy efficiency of the housing stock.