Daylight Harvesting in Tropic

Transcription

1 Daylight Harvesting in Tropic

2 Daylight space when done right is much nicer environment than electrically lit spaces.

3 Efficacy lm/watt Daylight is Cool & Free 280 Luminous Efficacy HPS & LPS = Conventional Street Lights Today

4 Useful Daylight Dr. John Mardaljevic recommended Useful Daylight as 100 lux to 2,000 lux Direct Sunlight > 100,000 lux

5 Daylight Factor DF = E internal E external x 100% Where, DF = Daylight Factor (%) E internal = Horizontal Illumination of reference point indoor (Lux) E external = Horizontal Illumination of unobstructed point outdoor in an overcast sky condition (Lux)

6 100% % of Hours > 100 lux Level (Diffuse Light Only) 80% Daylight Availability, 100 lux 60% 40% 20% 8-18 hours 9-17 hours 0% Daylight Factor (%)

7 100% % of Hours > 300 lux Level (Diffuse Light Only) 80% Daylight Availability, 300 lux 60% 40% 20% 8-18 hours 9-17 hours 0% Daylight Factor (%)

8 100% % of Hours > 2,000 lux Level (Diffuse Light Only) 80% Daylight Availability, 2000 lux 60% 40% 20% 8-18 hours 9-17 hours 0% Daylight Factor (%)

9 Key Principles of Daylight Harvesting 1. Solar Heat Gain Minimization 2. Glare Prevention 3. Deep Penetration Of Daylight 4. Uniform Daylight Distribution 5. Electrical Light Response To Daylight Harvested 6. Interior Design Colour

10 SOLAR HEAT GAIN MINIMISATION Rule 1 Avoid Direct Sunlight Too much light, too much heat Rule 2 Make use of Glazing Technologies, External Blinds, and Internal Blinds.

11 GLAZING TECHNOLOGY

12 UV Solar Spectrum

13 Visible Light Transmission (VLT) % of Light Transmitted Through Glazing

14 Solar Heat Gain Coefficient (SHGC) Total amount of solar heat that passes through the glazing.

15 Light to Solar Gain Ratio (LSG) Higher Value = More Light, Less Heat Lower Value = Less Light, More Heat LSG = VLT (%) SHGC(%)

16 U-value (W/m²K) A measure of conduction heat gain through the glazing unit.

17 Low-Emissivity (Low-E) Low Radiation Heat Transfer

18 Hard-Coat metallic oxides. Acceptable to be exposed to internal space. Single Glazing Low-E

19 Double Glazing Low- E Soft-Coat metallic oxides Requires protection.

20 LSG Typical Values LSG 1.6 ~ 2.0 = Double Glazing Low-E LSG ~ 1.2 = Single Glazing Low-E Colour of Glazing and LSG Clear, Green, Blue have higher LSG Red, Bronze have lower LSG

21 EXTERNAL AND INTERNAL SHADINGS

22 Solar Heat Reduction SHGC total = SHGC ext x SHGC glz x SHGC int Cases SHGC ext shades SHGC int shades SHGC Computed Descriptions glazing SHGC total 1 Poorly designed façade % 2 Only 1 item done well % % SHGC reduction 3 Only 1 item done well % 4 5 Two (2) items done moderately well All 3 items done moderately well % % 6 All 3 items done well %

23 DAYLIGHT STRATEGIES

24 Glare Prevention Maximum 10% view of the sky. 0% of Direct Sunlight. No Glare!

25 Deep Penetration of Daylight

26 Uniform Daylight Distribution Descriptions Between task and adjacent surroundings Max. Brightness Contrast Ratio 3

27 Daylight Responsive Lighting Lighting Zone 1 Lighting Zone 2 Task light (example) Lighting Control Automatic off (light sensor and/or occupancy sensor) Manual on (people press the wall switch) Use task light (table lamp)

28 Electrical Lights & Daylight

29 Interior Design Dark Coloured Interior absorb daylight.

30 Design Tools Manuals Tables and Charts BRE Daylight Factor Protractors Computer Simulation Dialux, Relux, etc. Radiance

31 Classic Daylight Harvesting

32 Glare will KILL Daylighting!

33 Malaysia Green Technology Center, Bangi, Kuala Lumpur

34 National Renewable Energy Laboratory (NREL), in Golden, Colorado

35 Right Sizing Windows Area on Facade Provide glazing area adequate for uniform daylight harvesting. More glazing area will provide more heat gain than energy saved through daylight harvesting.

36 Façade Daylight Harvesting No Glare!

37 Daylight Factor of 1% with Horizontal Blinds

38 Full Height Window

39 < 1 m ~ 0.6 m No Glare! ~ 1.5 m No Glare!

40 Daylight Factor with and without Furniture

41 Roof lights Skylight. Not suitable for office space. Acceptable for public space. Saw Tooth Roof Light. Diffuse light only. Acceptable for office space. Acceptable for public space. Roof Monitor. Diffuse light only. Acceptable for office space. Acceptable for public space.

42 Recommended Daylight Factor Atrium Space. 1% to 6%. 1% is equivalent brightness to an office space. 6%, where 50% of the daytime hours, the lux level is above 2,000 from diffuse daylight. 4% where 0% of the hours, the lux level is above 2,000 from diffuse daylight.

43 Skylight Design

44 Low-Rise Atrium: 2 Story height (8 m) Large Roof (16m x 16m): 5% skylight = 4% DF ave. 10% skylight > 10%. DF ave. Small Roof (8m x 8m): 5% skylight = 2% DF ave. 20% skylight = 6% DF ave.

45 Medium-Rise Atrium: 5 floors (20 m) Large Roof (16m x 16m): 5% skylight = 1% DF ave. 20% skylight = 3.5% DF ave. Small Roof (8m x 8m): 20% skylight = < 1% DF.

46 High-Rise Atrium: 10 floors (40m) Large Roof (16m x 16m) 40% Skylight = 1% DF ave.

47 BENEFITS OF DAYLIGHT

48 Regulate Circadian System Better Sleep Lower Blood Pressure Obesity Diabetic

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50 End of Chapter 4