Dagslys, indeklima og energibalance Betydningen av dagslys i bygninger – hvad er et godt indeklima og hvad er energibalance? Jens Christoffersen, VELUX A/S 1 Title/Department/Archive/Author

We prefer daylight Daylight is free and effective Daylight is available from sunrise to sunset; and working hours Significant energy saving potentials Quality: View, light, and variation Why Daylight...?

© Thomas Drejer, LouisPoulsen, LTS - møde Hvad er god lysstyring? Why daylight? © Lars B. Hansen, Philips Lys, LTS - møde Hvad er god lysstyring?

Next level of daylighting design Daylight, Health & well-being - all aspects

M. Knoop - Dynamic lighting for well-being in work places. Philips Lighting, LiDAC & TU/e, October 2006 Visual aspects of light

Adequate Daylight - Daylight factor = 2%…? The daylight factor (DF) express the daylight availability in a room. It describes the ratio of inside illuminance over outside illuminance, expressed in per cent. The higher the DF the more natural light is available in the room. The DF is often expressed for a fixed point within the e.g at the desk or at the centre of the room

Adequate Daylight - Daylight factor = 2%…? North-facing in St. Petersburg or South-facing in Miami? For a given design you get the same daylight factor either way, independent of orientation, climate, latitude etc. BUT interior light levels is different: Overcast, winter (DK): E ud ≈ lux → E ind ≈ 100 lux Overcast, summer (DK): E ud ≈ lux → E ind ≈ 600 lux

Adequate Daylight - Daylight factor = 2%…? 8

9 Krav til dagslys kan verifiseres enten ved beregning som bekrefter at gjennomsnittlig dagslysfaktor i rommet er minimum 2 %.... eller ved at rommets dagslysflate utgjør minimum 10 % av bruksarealet. Ved bruk av gjennomsnittsverdi for dagslysfaktor oppnås et godt utgangspunkt for tilfredsstillende tilgang på dagslys i alle typer rom, uavhengig av størrelse.

Adequate Daylight - Daylight factor = 2%…? 10

Adequate Daylight - Daylight factor = 2%…? 23 forskellige modeller med sidelys eller ovenlys Dagslysflaten er 10 eller 15% af gulvareal (≈ bruksflaten ?) Kun 9 ud af 23 modeller har en gennemsnittelig DF ≥ 2% Kun 1 ud af 23 modeller med sidelys har en dagslysflate på 10% og en gennemsnitlig DF ≥ 2% 2 modeller med ovenlys og dagslys- flate på 7% gav en gennemsnitlig DF ≥ 2% 11

Adequate Daylight - Daylight factor = 2%…? 12 British Standard BREEAM (and LEED, DGNB) DIN

The building design need to include a number of parameters, such as: daylight and sunlight penetration window views and content of view enclosed or open space crowding visual and acoustical privacy personal control of ambient conditions etc. light levels appropriate for ‘task’ glare from windows ……… Daylight and Windows Is it possible to address a more 'holistic' approach to daylight requirements?

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Useful Daylight Illuminance A human-factors based daylight metric

Emotional aspects of light

Research identified benefits of daylight and sunlight as well as view for worker health and well-being Less eyestrain (Cowling et al., 1990), higher productivity (Visher 1989), more effective learning (Heshong et al 1999) Daylight is better for psychological comfort, for office appearance and pleasantness, for general health and visual health, and for color appearance of people and furnishings (Heerwagen et al., 1986) Surveys consistently show that people prefer daylight over electric light and that they believe it to be more healthful (Heerwagen & Heerwagen, 1986; Veitch et. Al, 1993 / 1996). Having a window, or having access to daylight, improves satisfaction with lighting (Christoffersen et al., 1999; Butler & Biner, 1989; Cuttle, 1983; Heerwagen & Heerwagen, 1986, Veitch et al., 2003), and satisfaction with the view from an office is greater for natural scenes than man-made scenes (Christoffersen et al., 1999). The Role of Daylight

Non-visual aspects of light

People in industrialized countries might not be receiving sufficient daily light exposure to maintain optimal health (CIE, 2004) Necessary daily light dose is not known and the describing optimal pattern of light exposure is in its early stages. The implications for daylighting, architecture, and lighting design are unknown. Daylight and Health

Several studies have found that people who receive higher daily light exposures show improved mood, improved quality of social interactions, and greater feelings of vitality aan het Rot et al., 2007; Espiritu et al., 1994; Kripke et al., 2005; Leppamaki et al., 2004; Leppämäki et al., 2002 Electric lighting could meet the needs for daily light exposure But the need to improve energy-efficiency and reduce greenhouse gas emissions means that the most efficient way to increase daily light exposure will likely involve increased use of daylighting in new buildings and in retrofits of existing buildings..... and maybe accept ‘new working rules’ according to time-of-day walks, e.g. Wirz-Justice et al. (1996) found that subjects with SAD were treated more successfully by taking a one-hour walk each morning (illuminance ~ 1000 lx) than by 30-minute exposure to bright electric light (illuminance ~ 2800 lx) Daylight and Health

22 Indication of the relationship of subjective sleep quality as a function of vertical illuminance at the daytime working place (Ariens, 2005). Higher daytime illuminance – Better sleep quality

Indoor Environment and SAD 23 Around % of the population in Northern Europe is suffering from SAD or a milder form of seasonal mood disturbance. It helps to: Make your environment sunnier and brighter Get outside / Exercise

Daylight and Windows Is it possible to address a more 'holistic' approach to daylight requirements?

28 Ventilation and indoor air quality

Ventilation – why? Health: Remove chemicals, particles, smells, allergenes, moulds The human factors Psychological: Create link to outside Health: Avoid allergies, asthma, cardiovascular and other illnesses Performance: Support productivity and feeling of well-being Less illnes with good air quality Higher productivity with good air quality Comfort: Achieve thermal comfort 29

We see an increase in illnesses which is considered to be linked to the indoor environment Data for Sweden (Bråbäck et al 2004) Indoor Environment and Health

Temperature ( o C) Performance Increased temperatures and poor air quality can reduce performance of office workers by 5% to 10% Indoor Environment and Health Pawel Wargocki, Indoor Air 2011

32 If children are taught in a good indoor climate their ability to learn increases by 15% Pawel Wargocki, Indoor Air 2011 Indoor Environment and Performance Students with the most daylighting in their classrooms progressed 20% faster on math tests and 26% on reading tests. by HESCHONG MAHONE GROUP, 1999

End Users ?

Transfer of knowledge We need to bring our knowledge to the designer, as one of the main targets Essential that the information provided is clear, simple and context-specific to minimize poor design resulting in short- and long-term effects of the people within the building. Not adopt research results into a building design that is completely different from the context in which they where found. And we need also some common language

◘ From Marie-Claude Dubois Transfer of knowledge

Active House - Specification Philosophy Performance-based criteria Criteria based on international standards and well-known methods Only the most essential criteria – to minimise evaluation workload Two types of criteria Quantitative; score 1 – 4 Qualitative #36

Active House - Specification #37 Energy demand Thermal Environment Light & view out Indoor Air Quality Noise and Acoustics Energy supply Annual Energy Performance Consumption of non-renewable energy resources Emissions to air, soil and water Freshwater consumption and waste water treatment

Daylight 38

39 Direct sunlight availability

Thermal Environment (1) #4040

Indoor Air Quality (1) #41

Indoor Air Quality (2) #42

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Focus on U-value in legislation – but incorrect only to consider heat loss and not gain to evaluate the window’s effect on the building “Energy balance” includes both heat loss and solar gains – more fair than just U-value and provides a better choice of product Windows and Energy From U-value to energy balance 44 Solar gain Heat loss Energy balance

Energy balance Energy balance is expressed in kWh/m² of window If positive: the window contributes with energy for heating during the heating season If negative: the window is a cause of heat loss during the heating season 45 Solar gain Heat loss Energy balance

Energy balance - orientation 46 From method in the Danish 2010 building regulations Same heat loss in all orientations More solar gains towards S  Best total performance in S

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- it’s all about finding the right balance © Lars Hansen & Politiken, 2003

… and not leave us in “search of the good light“ …

.... but also enjoy the exterior light ! - with care!

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