Effect of energy renovation on thermal sensation and comfort 9th Nordic Symposium on Building Physics Riikka Holopainen VTT Technical Research Centre of Finland
2 Human Thermal Model (HTM) developed for predicting thermal behaviour of the human body under both steady-state and more realistic dynamic indoor environment boundary conditions realistic tissue distribution blood circulation system metabolism, respiration thermoregulatory system: control of skin blood flow, sweating, shivering interaction with the space by conduction, convection, radiation and evaporative heat transfer
3 HTM as a module of the VTT House building simulation tool adaptive thermal comfort approach: effect of human thermoregulation connected on thermal sensation and comfort estimates e.g. effects of alternative building structures and building service systems on thermal comfort thermal sensation can be used as a design parameter resulting in better thermal environments of new or renovated buildings
4 Renovation case typical Finnish apartment building from 1970 wall structure 0.085 m concrete + 0.140 m mineral wool + 0.100 m concrete, U-value 0.36 W/m 2 K double glazed windows, U-value 2.4 W/m 2 K, g-value 0.75. mechanical exhaust ventilation system, radiator heating indoor set point temperature 21 C retrofitting solutions with U-values on Finnish very low-energy house level wall structure 0.085 m concrete + 0.360 m polyurethane (PUR) + 0.100 m concrete, U-value 0,10 W/m 2 K triple glazed windows, U-value 0.67 W/m 2 K, g-value 0.35
5 Simulation cases: 1. original walls and windows 2. original walls and new windows 3. retrofitted walls and original windows 4. retrofitted walls and new windows Space: living room 13.3 m2 Outer wall area: 5.4 m 2 Window area: 2.5 m 2
6 Weather data during simulation time typical 5-day* cold weather period in middle-finland outdoor temperature between -3 C and -39 C direct solar radiation on horizontal surface max 83 W/m 2 diffuse solar radiation on horizontal surface max 105 W/m 2 0-5 Direct radiation on a horizontal surface 120 Diffuse radiation on a horizontal surface Outdoor temperature, C -10-15 -20 Radiation, W/m 2 100 80 60 40-25 20-30 0 Day 1 Day 1 Day 2 Day 2 Day 3 Day 3 Day 4 Day 4 Day 5 Day 5 Day 1 Day 1 Day 2 Day 2 Day 3 Day 3 Day 4 Day 4 Day 5 Day 5 * 3.2. 7.2. Jyväskylä test year 1979
7 Operative temperature Original windows and walls Retrofitted outer walls Retrofitted windows Retrofitted windows and walls 21.8 21.6 21.4 Operative temperature, C 21.2 21.0 20.8 20.6 20.4 20.2 20.0 Day 1 Day 1 Day 2 Day 2 Day 3 Day 3 Day 4 Day 4 Day 5 Day 5
8 Mean skin temperature of the Human Thermal Model (HTM) Original windows and walls Retrofitted outer walls Retrofitted windows Retrofitted windows and walls 33.1 33.0 32.9 Mean skin temperature, C 32.8 32.7 32.6 32.5 32.4 32.3 32.2 32.1 Day 1 Day 1 Day 2 Day 2 Day 3 Day 3 Day 4 Day 4 Day 5 Day 5
9 Thermal sensation and thermal comfort scales -4-3 -2-1 0 1 2 3 4 4 3 2 1 0-1 -2-3 -4
10 Overall thermal sensation Original windows and walls Retrofitted outer walls Retrofitted windows Retrofitted windows and walls -0.4-0.5 Thermal sensation index -0.6-0.7-0.8-0.9 Day 1 Day 1 Day 2 Day 2 Day 3 Day 3 Day 4 Day 4 Day 5 Day 5
11 Overall thermal comfort Original windows and walls Retrofitted windows Retrofitted outer walls Retrofitted windows and walls -0.2-0.3 Thermal comfort index -0.4-0.5-0.6-0.7 Day 1 Day 1 Day 2 Day 2 Day 3 Day 3 Day 4 Day 4 Day 5 Day 5
12 Predicted percentage of dissatisfied Original windows and walls, HTM Retrofitted windows and walls, HTM Original windows and walls, Fanger Retrofitted windows and walls, Fanger 34 32 30 Predicted percentage of dissatisfied, % 28 26 24 22 20 18 16 14 12 10 8 6 4 2 0 Day 1 Day 1 Day 2 Day 2 Day 3 Day 3 Day 4 Day 4 Day 5 Day 5
13 Conclusions improving the thermal resistance of the building structure increases thermal comfort during the heating season higher inner surface temperatures of retrofitted structures increase the operative indoor temperature and mean skin temperatures -> lower variation of temperature levels -> higher thermal comfort index new windows increased thermal comfort more than retrofitted walls (result depends on surface areas) total energy renovation decreased the annual heating demand of the test flat by 38 % increased indoor surface temperature levels decrease the radiation of cold surfaces -> lower indoor temperature demand -> further savings in energy cost
14 VTT creates business from technology