L11: Indoor climate targets for energy-efficient buildings. Helena Bülow-Hübe. Indoor climate

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1 L11: Indoor climate targets for energy-efficient buildings Helena Bülow-Hübe Indoor climate Discuss in 3 min: Between which temperatures is it comfortable to live and work? Should one make a difference between summer and winter case. If so, how? Do you think there are any cultural differences? Helena Bülow-Hübe 1

2 From The Swedish Work Environment Authority: At physically easy or sedentary work (sitting still), comfort is usually achieved at approx +22 C with normal clothing, or at approx +24 C in light summer clothing. If the air temperature is above +26 C for prolonged times there is a reason to investigate the thermal comfort more closely. Measures are normally required if the temperature more permanently is above +30 C. Thermal comfort definitions? The state-of-mind when you are satisfied with the thermal climate Abscence of discomfort regarding the thermal climate A state where at least 80% of all individuals does not percieve discomfort What parameters affect our comfort? Helena Bülow-Hübe 2

3 What parameters affect thermal comfort? Air temperature Radiation temperature Relative humidity Air velocity Level of activity Clothing Thermal comfort (P. O. Fanger) SS-EN ISO 7730 PMV Predicted Mean Vote 7-grade scale corresponding to the sensations of: hot, warm, slightly warm, neutral, slightly cool, cool, cold. Neutral equals zero (0). PPD Percentage People Dissatisfied Percentage of dissatisfied users. PPD is increased if the PMV moves up or down from the neutral state. PPD can never be zero in a larger population of people. Helena Bülow-Hübe 3

4 Insulation of clothing The insulation or thermal resistance of clothing is measured in the unit Clo 1 clo = m²k/w Lowest clo-value is 0 (naked body) Highest practical clo-value = 4 clo (Inuitclothing, fur pants, fur coat, hood, gloves etc.) Summer clothing ~ 0.6 clo Winter clothing ~ 1 clo Thermal comfort: Clothing 1 clo keeps a sitting man (1 met = 1 metabolic rate) comfortable at 21 C, 50% RH, 0.01 m/s Helena Bülow-Hübe 4

5 Optimal operative temperature Helena Bülow-Hübe 5

6 Global operative temperature distributions in a room (from ParaSol) Window Summer case Winter case PMV winter case (-18 C) Helena Bülow-Hübe 6

7 PPD winter case (-18 C) PPD summer case Winter clothing No air movement Summer clothing Air speed 0,4 m/s Helena Bülow-Hübe 7

8 Boverkets byggregler, BBR: (Swedish building code, BBR) Följ länken: publikationer, Boverkets byggregler 6:411 Tillämpningsområde Kraven på termiskt klimat gäller i hela byggnaden. Kravet på termisk komfort gäller rum eller avskiljbara delar av rum där människor vistas mer än tillfälligt. (BFS 2006:12) 6:412 Definitioner/beteckningar Vistelsezon: Vistelsezonen begränsas av två horisontella plan, ett på 0,1 meter höjd och ett annat på 2,0 meter höjd, samt vertikala plan 0,6 meter från ytterväggar eller andra yttre begränsningar, dock 1,0 meter vid fönster och dörr. Dimensionerande vinterutetemperatur, DVUT: Beräknas med hjälp av SS-EN ISO som medelvärdet av mean n-day air temperature och hourly mean air temperature. Strålningsasymmetri: Skillnad i värmestrålning till omgivande ytor. Helena Bülow-Hübe 8

9 6:42 Termisk komfort Byggnader och deras installationer skall utformas, så att termisk komfort som är anpassad till utrymmenas avsedda användning kan erhållas vid normala driftsförhållanden. (BFS 2006:12) Allmänt råd Byggnader bör vid DVUT utformas så att den lägsta riktade operativa temperaturen i vistelsezonen beräknas bli 18 ºC i bostads- och arbetsrum och 20 ºC i hygienrum och vårdlokaler samt i rum för barn i förskolor och för äldre i servicehus och dylikt, den riktade operativa temperaturens differenser vid olika punkter i rummets vistelsezon beräknas bli högst 5K och yttemperaturen på golvet under vistelsezonen beräknas bli lägst 16 ºC (i hygienrum lägst 18 ºC och i lokaler avsedda för barn lägst 20 ºC) och högst 26 ºC. Dessutom bör lufthastigheten i ett rums vistelsezon inte beräknas överstiga 0,15 m/s under uppvärmningssäsongen och lufthastigheten i vistelsezonen från ventilationssystemet inte överstiga 0,25 m/s under övrig tid på året. Requirements: Winter case Lowest operative temperature recommended is +18 C in dwellings and work places and +20 C for hospitals, pre-schools, elderly inst. This should be achieved for the coldest winter day, i.e. for DVUT* for the city and building type (dependent on thermal mass) DVUT is approx 10 to 13 C for south Sweden for a time constant of 300 h * Dimensionerande vinterutetemperatur Helena Bülow-Hübe 9

10 Summer case No standardized requirements like for the winter case. A common requirement is to say that the indoor air temperature should not exceed for example 25 C (or 27 C) for more than 10 days in July for a normal year. Not specified what outdoor temperature, solar radiation and relative humidity that the requirements and thus cooling unit should be designed for > everybody does it their way? Temperature duration whole year simulation (8760 hours) Temperature ( C) Air temperature Operative temperature Duration (hours) Helena Bülow-Hübe 10

11 Criteria and evaluation? The criteria is usually for working hours, i.e Mon-Fri 8-17 or similar. This means that these hours should be sorted out of the yearly simulation! Always discuss requirements for indoor temperature and outdoor design day criteria with the customer! Example, work place. Simulation for a whole year, values for July sorted out: Temperature ( C) Example of temp requriement: Operative temperature should not exceed 27 C for more than 10 days in July (P27) h < 90 h --> ok! Operative temperature Air temperature Req. P27: 10 days 8-17 = 90 hours Duration (hours) Note: The shown duration curve includes all hours of July (31*24=744 hrs). If the temperature req. is for working hours (approx 22 days*9 hrs = 198 hrs) this comparison is not correct, but criteria will be met anyway, since it is met for all hours of July. Helena Bülow-Hübe 11

12 R1 - Riktlinjer för specifikation av inneklimatkrav Guidelines for specification of indoor climate requirements Written by Lars Ekberg, for VVS-tekniska föreningen (the Swedish HVAC association), Recommendations according to R1 Target values for operative temperatures Helena Bülow-Hübe 12

13 Two climate classes, TQ1 & TQ2 R1 recommends that it is reasonable to allow a higher indoor temperature for about 80 working hours per year. Other thermal requirements may include floor temperature, vertical temperature gradient, radiation asymmetry and risk of draught Helena Bülow-Hübe 13

14 Maximum air velocity (to avoid draught) Summary thermal requir. Winter time (heating season) Desired temperature C Summer time (cooling season) Desired temperature C Allow higher indoor temperatures for about 80 working hours per year Air velocity Max 0,15-0,25 m/s depending on temperature Helena Bülow-Hübe 14

15 Other organisations for indoor climate criteria Scanvac, Rehva (Federation of European Heating and Ventilation Association), Ashrae (American Society of Heating, Refregerating and Air-Conditioning Engineers), Examples of additional criteria for energy-efficient buildings Annual energy use Max installed power for lighting e.g W/m² SPF-values for the ventilation system (Specific Fan Power, kw/m3,s) defines how much electric power is needed to move 1 m3 of air during 1 second e.g kw/m3,s yearly average Helena Bülow-Hübe 15

16 Other criteria Indoor air quality (min. fresh air flow rates, CO2-levels, other emissions) Noise levels (building acoustics) Lighting (illumination levels, glare, colour rendering, electricity use etc) Hot water temperature to avoid legionella (>50 C in all parts of system, >60 C where water stands still, <60 at faucet to avoid burns) Electromagnetic fields Radon levels Building system description Example of what should be included in a systems description regarding indoor climate and ventilation Helena Bülow-Hübe 16