introduction to simulating leedv4 daylighting...

DIVA Day / Introduction to SImulating LEEDv4 Daylighting Credit Compliance 12 October 2014

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

2 October 2014

J. Alstan [email protected]

CTO, Solemma LLC


A Very Brief History of LEED Simulation-based Daylight Credit Compliance

LEED 2.1 (2002)

LEED 2.2 (2005)

LEED 2009 (2009)

LEED 2009 Addendum

LEEDv4 (2013)

Achieve a minimum Daylight Factor of 2% (excluding all direct sunlight penetration)

in 75% of all space occupied for critical visual tasks.

Achieve at least 25fc illuminance in 75% of all regularly occupied areas under clear sky

conditions at noon on the equinox.

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.

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.

Achieve a Spatial Daylight Autonomy (sDA300lx,50%) in 55% (2pts) or 75% (3pts) with

Annual Sunlight Exposure (ASE1000lx,250h) below 10% in all regularly occupied floor areas.


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 (sDA300lx,50%)

∆ Annual Sunlight Exposure (ASE1000lx,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)


Standardized Occupancy Schedules

8AM - 6PM daily, 365 days per year. 10 * 365 = 3650 occupied hours in a standard year.


Shading Controls

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.

6.9% Direct Sunlight7am Sept 21, Boston, MA USA

24.6% Direct Sunlightnoon Sept 21, Boston, MA USA

2.7% Direct Sunlight5pm Sept 21, Boston, MA USA

Percentages of direct sunlight present in a space as calculated with DIVA.


Modeling Guidelines

When unknown, use the following...

- 30% vertical exterior surfaces reflectance

- 20% trees reflectance

- 10% ground reflectance

- 20% floor reflectance

- 50% wall reflectance

- 70% ceiling reflectance

- 50% furniture reflectance

Material Properties

Model fixed furniture 36” above the floor and

greater within 6” of accuracy.

Furniture


sDA300lx,50%

Three Annual Simulations Piece Together Results

Shades Open

• sDA300lx

Percentage of occupied hours

where 300 lx is met by daylight

alone.

• sDA300lx,50%

If the sDA300lx percentage

of hours > 50%, the area

represented by the sensor is

daylit. Typically the floor area

meeting this requirement.

• LEEDv4

If sDA300lx,50% comprises > 55%

of floor area, you get two LEED

points. >75% of floor area,

three LEED points.

Shades Closed (*N states)

Direct Sunlight Only (ab 0)Close shades when

sunlit area > 2%

Hour 1

.

.

.

Hour 09

Hour 10

Hour 11

Hour 12

Hour 13

Hour 14

Hour 15

Hour 16

Hour 17

.

.

.

Hour 8760

dir

ect

sun

nlig

ht

>2%

flo

or

area


sDA300lx,50%: Three Annual Simulations, Pieced Together

Shades open. Red = 300 lx.

sDA300lx Results

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.


ASE1000lx,250h: Very Simple

• No window shades. One 0 ambient bounce simulation --

direct sunlight only.

• Result is the number of occupied hours greater than 1000lx.

• Try to have less than 250h (6.85% occ-h).

ASE1000lx Results




Example Building: Net Zero Energy School in Boston Climate

Note: Furniture is actually not included in these simulations.


Second Floor Analysis


Daylit Areas (green)


LEED NC2.1: Daylight Factor

2

0

1

1.5

0.5

Daylight Factor(%)

18.4% of floor area has a DF%>2.

Requirement: 75% of floor area.


LEED 2009 Addendum: Equinox Illuminance at 9AM

500

> 500

illuminance (fc)

10

< 10

255

378

133

62.5% of floor area is between 10-500fc at 9AM

on a clear equinox day.


LEED 2009 Addendum: Equinox Illuminance at 3PM

500

> 500

illuminance (fc)

10

< 10

255

378

133

51.2% of floor area is between 10-500fc at 3PM

on a clear equinox day.


LEED 2009 Addendum: Both Illuminance Calculations

comply

9am does not comply

3pm does not comply

both do not comply

51.2% of floor area is between 10-500fc at 9AM

and 3PM on a clear equinox day.

Requirement: 75% of floor area.


LEEDv4: Spatial Daylight Autonomy

100sDA (% occ.-h)

0

50

75

25

27.5% of the floor area has a sDA300lx value

greater than 50% of occupied hours.

Requirement: 55% of floor area (2pts).

75% of floor area (3pts).


LEEDv4: Annual Sunlight Exposure

250

> 250

ASE >1000lx (h)

0

125

188

63

10.9% of the floor area has a ASE1000lx value

greater than 250 hours.

Requirement: Less than 10% of floor area.


Panel Discussion

Ed Clark Eddy Santosa Kevin Van Den Wymelenberg

Associate Professor, U. Idaho

Director, Integrated Design Lab

Chair, IESNA Daylight Metrics

Committee

Building and Energy

Performance Group, Callison

Associate, ZGF Architects LLP

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