The New European Standard (prEN 17037) in
Buildings – A Brighter Future ?
Part 2
Jens Christoffersen & John Mardaljevic
VELUX A/S, Hørsholm, Denmark
School of Civil & Building Engineering, Loughborough University, UK
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CEN / TC 169 WG 11
“Daylight”
Active Members:
Austria, Belgium, Czech Republic, Denmark, France, Germany, Italy,
Norway, Slovakia, Slovenia, Sweden, Switzerland, The Netherlands, UK
linked to
CEN/TC 169 WG 2 Lighting of Workplaces
CEN/TC 169 WG 9 Energy Performance of Buildings
CEN/TC 169 WG 13 Non-Visual Effects of Light on Human Beings
Objectives:
Develop European Standard for “Daylight of Buildings”
Daylight Factor
Daylight Factor (DF) values can, today, be recommended
in various national standards and legislations
… and they are often presented differently – as an average, in
a point(s) or as a percentage of the room area
British Standard BS 8206-2
German Standard DIN 5034-1
BREEAM, LEED, DGNB
% of
room area
DF in a grid
of calculation
points for a
% of a space
DF is a ratio between internal and external illuminance [lux]
Average DF
in a space
DF in one or
more calculation
points in a space
…so the intention of working group was:
to develop a (new) common methodology for
daylight provision in buildings, which could
consider variations related to geographical and
climatic differences in Europe.
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CEN Daylight Standard (prEN 17037)
Daylight
View
Sunlight
Glare
Applies to all spaces (e.g workplaces and dwellings)
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Scope
This standard specifies recommendation for [minimum]:
Achieving an adequate subjective impression of lightness indoors
Adequate view out
Duration of sunshine exposure within habitable and occupied rooms
How to limit glare
Defines metrics used for the evaluation of daylighting conditions and
gives methods of calculation and verification.
This standard applies to all spaces that may be regularly occupied by
people for extended periods.
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Content
Informative
Normative
Scope, Terms and definitions, Symbols
Section 5 Assessment of Daylight
•
•
•
•
Daylight provision and calculation
View out
Sunlight
Glare
Section 6 General considerations
Section 7 Verification
Annex A : Minimum recommendations
Annex B :
method for
daylight
provision
Annex C :
method for
view out
Annex D :
method for
sunlight
exposure
Annex E :
method for
glare
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Daylight
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CEN Daylight Standard (prEN 17037)
- Target interior illuminance
A number of studies have demonstrated that 300 lux of
natural illumination is considered adequate by the majority of
building users
Design levels for artificial lighting (EN 12464-1) are often set
at the 300 lux in office, school etc.
The minimum target illuminance recommendation (100 lux)
acts a safeguard against very poorly illuminated spaces
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CEN Daylight Standard (prEN 17037)
- Target interior illuminance
A number of studies have demonstrated that 300 lux of
natural illumination is considered adequate by the majority of
building users
300 lux (target)
Correlates with the notion of a well-daylit space
CIE report `Daylight‘ (1970): 300 lux is described as suitable illumination
for “prolonged office work”
Design levels for artificial lighting (EN 12464-1) are set at the 300 lux mark
“Switch-on” probability for electric lighting is high for illuminances less than
100 lux and very low for illuminances 300 lux or greater
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CEN Daylight Standard (prEN 17037)
- Target interior illuminance
100 lux (target minimum)
Evaluations carried out on a number of typical side-lit office and classroom
spaces indicated that the minimum daylight factor is often not less than one
third times the daylight factor in the middle of the space.
The minimum illuminance recommendation acts a safeguard against very
poorly illuminated spaces
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CEN Daylight Standard (prEN 17037)
- Daylight recommendation
4m
DT ≥ 2.0%
6m
Daylit area ≥ 41%
Window 1,73x1,73
W/floor = 1:8
Daylit area ≥ 23%
Window 1,73x1,73
W/floor = 1:8
Daylit area ≥ 21%
Window 1,07x2,8
W/floor = 1:8
The examples shows that daylight performance for the
same window-to-floor ratio can vary significantly, with
daylit area (DF ≥ 2.0%) ranging from 21% to 100%.
Daylit area ≥ 38%
Windows(2) 1,0x1,5
W/floor = 1:8
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View
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Daylight standard prEN 17037 - View
General principle
Horizontal sight angle
Outside distance of view
Amount of layers seen
from inside
?
?
?
?
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Daylight standard prEN 17037 - View
Horizontal sight angle
Rating of view-out
Width of window(s),
horizontal sight angle
Minimum
Medium
High
> 14°
> 28°
> 54°
Evaluation:
Through actual view angle
 Eyelevel at 1,2 m if sitting
 Eyelevel at 1,7 m if standing
… but no software available yet
Or medium level simplified evaluation
 Minimum window width and height: 1.0 x 1,25 m
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Daylight standard prEN 17037 - View
Horizontal sight angle evaluation – simplified method
One façade
with windows
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Daylight standard prEN 17037 - View
Outside distance of view
Ensure minimum distance to external obstacles
 Necessary for eye focus relaxation
To be evaluated through
architectural sketches
Rating of view-out
Outside distance of
the view
Minimum
Medium
High
>6m
> 20 m
> 50 m
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Daylight standard prEN 17037 - View
Amount of layers seen from inside
Rating of view-out
Minimum
Medium
Number of layers to be seen
from at least 75% of utilized
area
At least
landscape
layer is
included
Minimum 2
layers are
included
High
All layers are
included
Use the “no-sky” and “no-ground” lines principle
Layers can be:
Sky
Landscape
Ground
Landscape
Could be
evaluated
through
sketches
or on-site
Ground
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Sunlight
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Daylight standard prEN 17037 Sunlight
Purpose of the indicator
Ensure minimum direct sunlight hours
On the 21st of March
Evaluated at the centre of the window, at
1.2 m from the ground (sitting eye level)
Works for dwellings,
hospitals, kindergardens
Direct sunlight hours recommendations (21st of March)
Recommendations
Minimum
Medium
High
> 1.5 h
>3h
>4h
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Daylight standard prEN 17037 Sunlight
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Daylight standard prEN 17037 Sunlight
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Glare
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Glare
Daylight Glare Probability (DGP)
DGP < 0.35
0,35 < DGP
0,40 < DGP
DGP > 0,45
- Glare
< 0,40
< 0,45
- Glare
is mostly not-perceived
- Glare is perceived but mostly not disturbing
- Glare is perceived and often disturbing
is perceived and mostly intolerable
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Glare
Values of threshold DGPt for different levels of glare protection
Recommendations for DGPt
Minimum
Medium
High
0.45
0.40
0.35
Critical glare situations exceeding a threshold value DGPt should be
limited to a certain fraction of the reference usage time fDGP,exceed
tglare is the amount of time throughout the year when the DGP exceeds the
threshold DGPt.
tref is the time between 8h-18h on Monday to Friday throughout the year
Maximum exceeding time throught the year is 5%
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Glare
Simplified annual evaluation for Venetian blinds and fabrics is provided
Venetian blinds do not exceed a DGPt of 0,45 in more than 5 % of the
reference usage time, if:
• the blinds can be adapted by the user
• …and the blinds have no gaps and have the possibility to close completely
•
…and in case of perforation the view towards the sun is interrupted in the closed
position
Fabrics do not exceed a DGPt of 0,45 in more than 5 % of the reference usage
time, if the transmission values in tables is not exceeded. Transmission values
for fabrics depends on:
• Viewing direction and Façade orientation
• Glazing fraction of the façade and glazing transmission
• Distance of the user to the façade
• Visual direct-direct transmission
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Status of today
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2010 - 2015
Different challenges
in the development
2009/10
Initiate the
development
of a standard
Public Enquiry
July 28 – October 28
Public Enquiry, Vote:
2 No; 21 Yes
March 2016
Draft accepted for
Public Enquiry, Vote:
2 No; 12 Yes
Today
Timeline
2017/2018
Expected publication
of an European
Daylight Standard
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prEN 17037 Public Enquiry
Country
Yes
No
Weighting
Austria
X
10
Belgium
X
12
Bulgaria
X
10
Denmark
X
7
Estonia
X
4
Finland
X
7
France
X
29
X
Germany
Hungary
X
23 countries
21 YES and 2 No)
Yes ~ 82.6%
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No ~ 17.4%
12
X
Italy
Result of CEN/TC 169 WG
11 public enquiry
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Latvia
X
4
Lithuania
X
7
Malta
X
3
Netherlands
X
13
Poland
X
27
Romania
X
14
Slovakia
X
7
Slovenia
X
4
Spain
X
27
Sweden
X
10
Switzerland
X
10
Turkey
X
29
United Kingdom
X
29
30
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Q/A
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•
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•
•
•
•
•
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Thank you
[email protected]
[email protected]
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