Thermal Retrofitting Of Dormitory Under Historic Protection - Case Study Jerzy KWIATKOWSKI, Jerzy SOWA, Andrzej WISZNIEWSKI Warsaw University of Technology, Faculty of Building Services, Hydro and Environmental Engineering, jerzy.kwiatkowski@pw.edu.pl

nZEB standard in Poland In Poland a nZEB standard has been define by primary energy indicator (EP) For public buildings, like educational building maximal value of EP has been state as sum of three indicators: for heating and domestic hot water – 45 kWh/m2a; for cooling – 25*(Af,c/Af) kWh/m2a (where Af,c is a cooled area and Af is a total regulated temperature area); for lighting – 25 kWh/m2a for time of light operation <2500 h/year and 50 kWh/m2 a for time of light operation ≥2500 h/year. In total maximum EP may vary from 70 to 120 kWh/m2a. 1405

nZEB definition in KODnZEB project Energy consumption for: heating, cooling, hot water preparation, lighting, auxiliary energy for HVAC system, Dynamic hourly calculation Cost optimal EP indicator for educational building – 40 and 55 kWh/m2a Maximum EP <20 kWh/m2a 1405

Building description Part of a dormitory complex of Warsaw University of Technology build before 1939 and in 1950 1405

Energy performance of the building – existing state EP indicator [kWh/m2a] Heating and ventilation 140.8 Domestic hot water 69.1 Lighting 85.3 Auxiliary energy 3.3 PV installation Sum 298.5 Any modernizations must be agreed with heritage protection officer. 1405

Retrofitting measures - envelope Insulation of external walls –aerogel panels (λ=0,015 W/mK and the thickness of 4 cm); decrease of the heat transfer coefficient of walls from U=1,09 W/m2K down to U=0,279 W/m2K Insulation of the ceiling between the top floor of the building and the unheated attic - mineral wool (λ=0,035 W/mK and a thickness of 16 cm); decrease of the heat transfer coefficient of the ceiling from U=2,02 W/m2K down to U=0,197W/m2K Replacement of windows - an improvement of the heat transfer coefficient of windows from U=1,87 W/m2K to U=0,70 W/m2K; decrease the air tightness coefficient from n50=3,0 1/h down to n50=1,5 1/h 1405

Retrofittong measures - ventilation Mechanical exhaust ventilation with air to water heat recovery from living spaces: single rooms - 20 m3/h and 50 m3/h when the shower recess is used (+15 min after); for units when one shower recess is dedicated for 1 double and 2 single rooms - 0 active contactors - 20 m3/h, 1 active contactor - 50 m3/h, 2 or 3 active contactors - 80 m3/h Balanced mechanical ventilation with air to air heat recovery in other zones (corridors and staircase, shared kitchens, shared bathrooms, service rooms); Natural ventilation of unused rooms in the basement of the building. 1405

Retrofitting measures – other systems Space heating system - replacement of the radiators and installation of regulating valves Domestic hot water system - air to water heat pump using exhaust ventilation air flow from living units The lighting system - replacement of the existing lighting fixtures and light sources, installation of a lighting control system, reduction of lighting installed power from 11,22 W/m2 down to 3,34 W/m2 1405

Retrofitting measures - RES PV panels cannot be seen from the street level; PV system data: APV=374,8 m2; PPV=79,35 kWp; EPV=69 953 kWh/a 1405

Analysis of proposed measures Simple pay-back time [years] Decrease of primary energy indicator [kWh/m2year] Cost of reduction of primary energy indicator reduction [€/(kWh/m2year)] External wall 58.8 26.6 12 844 Roof 7.1 11.5 1 561 Windows 26.9 14.9 5 889 Ventilation system 5.7 69.4 1 286 Heating system 23.9 7.6 5 279 Lighting 73.9 48.0 4 405 Hot water system 0.6 33.3 131 Heat pump (hot water only) 9.1 42.6* 750 PV system 55.9 58.6 4 967 All measures 22.8 280.2 3 980 1405

Conclusions and remarks It was shown that by common work of architects, constructor and HVAC engineers EP ratio was decreased from 298,5 kWh/m2a to 18,3 kWh/m2a Such a result needs holistic approach (envelope, HVAC systems, lighting, BACS, RES) The internal thermal comfort has been incerased (decrease in hours with overheating) The economic efficiency of proposed measures is related to the specific of a building 1405

Jerzy KWIATKOWSKI jerzy.kwiatkowski@pw.edu.pl ID1405