Building envelope harmonisation according to the energy efficiency criteria in Bratsk
The article examines the impact of space planning decision of a building on the characteristics of its energy efficiency. The design data for the building envelope optimization applied in the conditions of Bratsk are analysed. The building energy efficiency can be influenced by both the absolute size (length, width, height, number of storeys) and the certain parameters ratio (outer shell specific area, exterior walls specific perimeter, the ratio of the window openings area ​ to the exterior walls). The optimum shape of the building has been determined, the ratio of housing length to its length as to the specific heat consumption has been calculated. This indicator is determined as the ratio of heat loss to the outer shell rentable space. The specific heating energy consumption q varies with the width and number of storeys. Maximum values ​​of this index are observed in one-storey buildings; when the number of storeys increases q goes down and most considerably in the interval from the first to the third floor. It has been proved that the reduction in energy consumption is achieved as a result of design and construction of multi-storey buildings occupying a large area on the plan. With the increase in the residential buildings housing length leading to the reduction of the outer shell specific area by 20 - 30% per 1 m <sup>2</sup>, heat losses are reduced by 15 - 20%.