Specifics of multi-apartment building deep complex retrofitting Anatolijs BORODINECS Institute of Heat, Gas and Water Technology, Faculty of Civil Engineering, Riga Technical University

Objectives To identify Latvian multi apartment building advantages and disadvantages; To evaluate energy saving potential; Study analyses theoretical as well as real measured multi-apartment building heat consumption before and after renovation

Latvian multi- apartment buildings Compactness factor of 9-store multi apartment building building is 0,28. For 5-storey multi-apartment building with 4 sections compactness factor for such building is 0,35.

Average occupancy rate

Disadvantages Non insulated building envelope High air leakage rate Small apartments Many apartments High energy consumption, low thermal comfort Advantages Homogeneous external wall Sufficient air exchange rate High occupancy rate Efficient building shape

'A business as usual' Consumption of 6 multi apartment buildings before and after renovation, in City Of Riga

Dynamic energy simulation Retrofitting solution Existing situation before renovation According to existing legislation without controlled ventilation According to existing legislation with mechanical ventilation with heat recovery Heat consumption for heating, kWh/m2 142,7 53,8 50,4 Heating consumption for Hot water , kWh/m2 56 Lighting, kWh/m2 16,7 Electricity consumption for ventilation, kWh/m2 14,3 Air infiltration of building envelope, 1/h 0,7* including windows opening 0,5* including windows opening ~0.028* windows are closed only mechanical ventilation

Nearly Zero Energy Building Latvian definition for apartment buildings: Heat consumption for heating – 40kWh/m2; Primary energy for heating, hot water, mechanical ventilation, lighting and cooling not more than 95kWh/m2; Heat recovery efficiently >75%; Use of renewable energy (amount is not clearly defined); Primary energy factor: Electricity – 1,5; District heating Co-generation Fossil fuels 0,7 Renewable energy 0,0 Boiler house 1,3 0,1

Retrofitting solution Existing situation before renovation According to existing legislation without controlled ventilation According to existing legislation with mechanical ventilation with heat recovery Heat consumption for heating, kWh/m2 142,7 53,8 50,4 Heating consumption for Hot water , kWh/m2 56 Lighting, kWh/m2 16,7 Electricity consumption for ventilation, kWh/m2 14,3 Primary energy 165 102 123,5 Solar collectors (heat) 285m2 = 29kWh/m2 1m2 – 350kWh per year

MORE-CONNECT case building Typical soviet building; Silicate brick building; Widely constructed in suburban and remote areas; Limited possibilities to apply for EU funds due to building size; Extra construction costs due to building remote location; Area – 559 m2;

Results Analysis of energy consumption of already renovated buildings have shown that in a typical situation it is possible to decrease the overall heat consumption by approximately 50% from 150-180 to 75-100 kWh/m2; Dynamic calculations performed 5storey multi-apartment building with 4 sections, have shown heat consumption reduction by 62% in case of building thermal insulation according to actual legislation. The installation of fully mechanical supply/exhaust ventilation system resulted in with increase of electricity consumption by 10,8 kWh/m². In should be highlighted that, lack of ventilation system in renovated buildings, resulted unsatisfactory indoor air parameters such increased CO2 concentration and high relative humidity.