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Evaluation of Daylight in Buildings in the FutureHelle Foldbjerg RasmussenTechnical Support ManagerMicroShade A/S
May 1, 2023 2
Consequences of the EU EPBD Directive
May 1, 2023 2
Low level of insulation
Single or 2-layer glazings
High air leakage→
Typical existing buildings (EU)
Typical buildings in existing building codes 2016 (EU)
High level of insulation
Low-e glazings (2- or 3-layer)
Low air leakage
Increased demand for progressive, movable or switchable solar shadings
Demand for shading systems with lower g- value than todays standard (max. 0.15)
Future buildings (EU)nZEB
→Solar irradiation needs to be minimized in summer
Some solar irradiation can be accepted in winter
May 1, 2023 3
Evaluation of Daylight - Daylight Factor (DF)
• DF is traditionally used in Building Regulations and Sustainable Certification Schemes such as DGNB
• Movable, switchable solar shading is NOT taken into account
• This calls for a new method to evaluate daylight in low energy buildings
DF = indoor daylight illuminance · 100% outdoor daylight illuminance
May 1, 2023 3
Outdoor daylightilluminance
Indoor daylightilluminance
↓
DF is calculated with an CIE uniform overcasted sky
New Method - Climate based daylight metrics
• Climate based daylight metrics– calculated based on actual weather data
including solar height, cloud cover fraction etc.
– takes all kind of solar shading into account– Eg. UDI, DA, sDA, ASE etc.
• UDI is the most informative daylight metric
May 1, 2023 4
0300 lux
2000 lux
0100 lux
3000 lux
UDI
Artificial light is needed
Chance of glare & direct solar discomfort
Supplementary artificial light needed
300 lux
000 lux
DA
May 1, 2023 5
Example: Low Energy Office Building
No Shading(Reference)
Solar Control (Cool-Lite Xtreme®)
External lamellas (45°)
External lamellas (90°)
External Light Screen
External DarkScreen
MicroShade® MS-A
Permanent shadings Dynamic shadings
Lamellas control: on/off @ 1000-1500 lux at workplane Screen control: on/off @ 500-1000 lux at workplane
to aim at a effective summer g-value of 0.15
South façadeCopenhagen40% glass to floor ratio3-layer low energy glazing
May 1, 2023 6
Daylight Factor and eff. summer g-value
No Shading Solar control (CLX)
MicroShade MS-A
Lamella 45° Lamella 90° Dark Screen Light Screen0
10
20
30
40
50
60
70
80
90
100
0
1
2
3
4
5
6
7
8
9
10
UDI<100 DF Eff. g-value summer
Effec
tive
sum
mer
g-v
alue
Daylight Factor
Permanent shadings Dynamic shadings
May 1, 2023 7
Daylight Factor, UDI and eff. summer g-value
No Shading Solar control (CLX)
MicroShade MS-A
Lamella 45° Lamella 90° Dark Screen Light Screen0
10
20
30
40
50
60
70
80
90
100
0
1
2
3
4
5
6
7
8
9
10
UDI<100 UDI100-300 UDI300-3000 UDI>3000 Eff. g-value summer DF
Perc
enta
ge o
f wor
k ho
urs
Daylight Factor
Permanent shadings Dynamic shadings
May 1, 2023 8
User experience - View out
No Shading Solar control (CLX)
MicroShade MS-A
Lamella 45° Lamella 90° Dark Screen Light Screen0
10
20
30
40
50
60
70
80
90
100
UDI300-3000 View out Eff. g-value summer
Perc
enta
ge o
f wor
k ho
urs (
8-17
)
Permanent shadings Dynamic shadings
May 1, 2023 9
Recommendations
• Solar shading must be taken into account when evaluating daylight in future low energy buildings
• The same control of shading must be used in both indoor climate and daylight simulations
• Evaluate the view out with the planned solution
