Introduction to Simulating LEEDv4 Daylighting Credit Compliance and IES-LM-83

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1 Introduction to Simulating LEEDv4 Daylighting Credit Compliance and IES-LM-83 J. Alstan Jakubiec CTO, Solemma LLC DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 1

2 A Very Brief History of LEED Simulation-based Daylight Credit Compliance LEED 2.1 (2002) Achieve a minimum Daylight Factor of 2% (excluding all direct sunlight penetration) in 75% of all space occupied for critical visual tasks. LEED 2.2 (2005) Achieve at least 25fc illuminance in 75% of all regularly occupied areas under clear sky conditions at noon on the equinox. LEED 2009 (2009) Achieve at least 25fc but no more than 500fc illuminance in 75% of all regularly occupied areas under clear sky conditions at 9AM and 3PM on the equinox. LEED 2009 Addendum Achieve at least 10fc but no more than 500fc illuminance in 75% of all regularly occupied areas under clear sky conditions at 9AM and 3PM on the equinox. LEEDv4 (2013) Achieve a Spatial Daylight Autonomy (sda 300lx,50% ) in 55% (2pts) or 75% (3pts) with Annual Sunlight Exposure (ASE 1000lx,250h ) below 10% in all regularly occupied floor areas. DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 2

3 IES-LM-83: What is it? In short, where the LEEDv4 daylighting compliance requirements come from. An approved method by the Illuminating Engineering Society (IES) Daylight Metrics Committee. This resulted in two new metrics for daylit spaces. Spatial Daylight Autonomy (sda 300lx,50% ) Annual Sunlight Exposure (ASE 1000lx,250h ) LM-83 also attempts to standardize many unknowns in typical simulation processes. Shading controls Occupancy Unknown material reflectances Workplane height and sensor spacing Modelling guidelines (furniture, window mullions, context) Simulation parameters (light reflections, simulation detail) DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 3

4 Standardized Occupancy Schedules 8AM - 6PM daily, 365 days per year. 10 * 365 = 3650 occupied hours in a standard year. DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 4

5 Shading Controls 6.9% Direct Sunlight 7am Sept 21, Boston, MA USA 24.6% Direct Sunlight noon Sept 21, Boston, MA USA 2.7% Direct Sunlight 5pm Sept 21, Boston, MA USA Percentages of direct sunlight present in a space as calculated with DIVA. When more than 2% of a space s floor area is covered by 1000lx of illuminance from direct sunlight (as in a 0 ambient bounce lighting calculation), shading devices will be lowered to block the sunlight. DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 5

6 Modeling Guidelines Furniture Material Properties Model fixed furniture 36 above the floor and greater within 6 of accuracy. When unknown, use the following % vertical exterior surfaces reflectance - 20% trees reflectance - 10% ground reflectance - 20% floor reflectance - 50% wall reflectance - 70% ceiling reflectance - 50% furniture reflectance DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 6

7 sda 300lx,50% Three Annual Simulations Piece Together Results Hour 1 Shades Open Shades Closed (*N states) Direct Sunlight Only (ab 0)... Hour 09 Hour 10 Hour 11 Hour 12 Hour 13 Hour 14 Hour 15 Hour 16 Hour Hour 8760 Close shades when sunlit area > 2% direct sunnlight >2% floor area sda 300lx Percentage of occupied hours where 300 lx is met by daylight alone. sda 300lx,50% If the sda 300lx percentage of hours > 50%, the area represented by the sensor is daylit. Typically the floor area meeting this requirement. LEEDv4 If sda 300lx,50% comprises > 55% of floor area, you get two LEED points. >75% of floor area, three LEED points. DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 7

8 sda 300lx,50% : Three Annual Simulations, Pieced Together sda 300lx Results Shades open. Red = 300 lx. Note: Shades close when the floor area exposed to direct sunlight >2% of the total. Shades closed. Red = 300 lx. Direct sunlight (ab 0). Red = 1000 lx. DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 8

9 ASE 1000lx,250h : Very Simple No window shades. One 0 ambient bounce simulation -- direct sunlight only. Result is the number of occupied hours greater than 1000lx. ASE 1000lx Results Try to have less than 250h (6.85% occ-h). Direct sunlight (ab 0). Red = 1000 lx. Direct sunlight (ab 0). Red = 1000 lx. DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 9

10 Example Building: Net Zero Energy School in Boston Climate Note: Furniture is actually not included in these simulations. DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 10

11 Second Floor Analysis DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 11

12 Daylit Areas (green) DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 12

13 LEED NC2.1: Daylight Factor 18.4% of floor area has a DF%>2. Requirement: 75% of floor area. Daylight Factor(%) DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 13

14 LEED 2009 Addendum: Equinox Illuminance at 9AM 62.5% of floor area is between fc at 9AM on a clear equinox day. illuminance (fc) > < 10 DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 14

15 LEED 2009 Addendum: Equinox Illuminance at 3PM 51.2% of floor area is between fc at 3PM on a clear equinox day. illuminance (fc) > < 10 DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 15

16 LEED 2009 Addendum: Both Illuminance Calculations 51.2% of floor area is between fc at 9AM and 3PM on a clear equinox day. Requirement: 75% of floor area. comply both do not comply 9am does not comply 3pm does not comply DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 16

17 LEEDv4: Spatial Daylight Autonomy 27.5% of the floor area has a sda 300lx value greater than 50% of occupied hours. Requirement: 55% of floor area (2pts). 75% of floor area (3pts). sda (% occ.-h) DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 17

18 LEEDv4: Annual Sunlight Exposure 10.9% of the floor area has a ASE 1000lx value greater than 250 hours. Requirement: Less than 10% of floor area. ASE >1000lx (h) > DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 18

19 Panel Discussion Ed Clark Eddy Santosa Kevin Van Den Wymelenberg Associate, ZGF Architects LLP Building and Energy Performance Group, Callison Associate Professor, U. Idaho Director, Integrated Design Lab Chair, IESNA Daylight Metrics Committee DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 19