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Guest lecture/presentation to the architecture students of University of Kansas at their Emerging Green Builders Forum on February 5, 2008
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Daylighting Analysis and Tools
Ramana Koti
Sustainable Building Analyst
Elements Division of BNIM Architects
Which of the following definitions for daylighting is the most relevant to you?
0
20
40
Architectural Building Energy
Consumption
Cost Lighting Energy
Savings
Load
Management
Designers (Lighting, Architects, Interior) Engineers & Energy Consultants
Source: Results of a 2006 survey on the role of daylighting in
sustainable design by Lawrence Berkeley National Laboratory and
National Research Council Canada – 120 Respondents
Role of Daylighting in Sustainable Design
Character of architecture in a region
emerges from the way designers
work with building form and the
fenestration to deal with light and
climate control. It advocates the use of
controlled daylight that, for example,
causes the exhibition volume in an art
gallery to change with time, season
and humidity, as opposed to the
exclusive use of artificial light.
Critical Regionalism
Climate Chart for Design Teams
Climate Consultant
Melaver Birmingham, Alabama
Melaver Birmingham, Alabama
A footcandle is a measure of light intensity. A footcandle is defined as the
amount of light received by 1 square foot of a surface that is 1 foot from a
point source of light equivalent to one candle of a certain type. Depending
on the sky conditions daylight can produce anywhere from 2,000 to
10,000 footcandles
Illuminance is the luminous flux per unit area on an intercepting surface at
any given point, expressed in footcandles. Commonly described as the
amount of light on a surface.
Luminance is the luminous intensity of a surface in a given direction per
unit of projected area, expressed in footcandles. Commonly described as
the amount of light leaving a surface.
Visual acuity is a measure of the ability to distinguish fine details.
Glare is the sensation produced by luminance within the visual field that is
sufficiently greater than the luminance to which the eyes have adapted to
cause annoyance, discomfort or visibility difficulty.
Common Terms
Climate
Climate consultant
Weathermaker
Weather Manager
Daylighting
Radiance
DAYSIM
IES <VE>
Ecotect
eQUEST
Energy Performance
Ecotect
IES <VE>
eQUEST
Energy 10
Glazing
LBNL Window
LBNL Optics
Modeling Tools
Project:
Four stories
120,000 square feet
$17.5 million - $145 / SF
LEED Certification:
Platinum – 53 points achieved
Team:
Architect: BNIM Architects
Owner: Missouri State Office of Administration
Tenant: Missouri Department of Natural Resources
Contractor: Professional Contractors + Engineers (PCE)
Lighting: Clanton Associates
Daylighting: Ensar Group
Lewis and Clark State Office Building, Jefferson City, Missouri
Lewis and Clark State Office Building, Jefferson City, Missouri
Lewis and Clark State Office Building, Jefferson City, Missouri
Lewis and Clark State Office Building, Jefferson City, Missouri
Lewis and Clark State Office Building, Jefferson City, Missouri
Lewis and Clark State Office Building, Jefferson City, Missouri
Lewis and Clark State Office Building, Jefferson City, Missouri
Lewis and Clark State Office Building, Jefferson City, Missouri
Lewis & Clark - Building Occupant Survey
80%
89%
43%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Overall Lighting in the building -
Comfortable or Neutral
Amount of Daylight -
Comfortable or Neutral
Perceive discomfort caused by
glare
Lewis and Clark State Office Building, Jefferson City, Missouri
Dynamic Sun/Sky conditions changing constantly
User behaviour
Differing methods/sky models used by different
tools
Raytracing tools like Radiance have a steep
learning curve
Lack of reliable metrics
Challenges to modeling Daylighting
KCPL Headquarters, Kansas City, Missouri
KCPL Headquarters, Kansas City, Missouri
KCPL Service Center, Lenexa, KS
KCPL Service Center, Lenexa, KS
Before – After, June 21 Noon Sunny, John Deere Service Shop, Greensburg, KS
LEED and Daylighting
Daylight Factor Approach
Single Point in Time
Approach (Simulated)
Single Point in Time
Approach (Measured)
Daylight Factor: The ratio of the internal illuminance at a
point in a building to the unshaded, external horizontal
illuminance under a CIE overcast sky. (CIE is the
Commission Internationale de l’Eclairage, which has
developed a series of mathematical models of ideal
luminous distributions under different sky conditions.)
Daylight Autonomy: For a sensor point, it is the
percentage of occupied times of the year when the
minimum illuminance requirement at the sensor is met by
daylight alone.
Useful Daylight Illuminances: Aims to determine when
daylight levels are useful for the occupant, in terms of being
neither too dark nor too bright (between 100 lux and 2000
lux).
Continuous Daylight Autonomy: Similar to Daylight
Autonomy except partial credit is attributed to time steps
when daylight illuminance lies below the minimum
illuminance level.
Daylight Saturation Percentage: The daylight saturation
percentage for 40 foot-candles (DSP40 ) to 400 foot-
candles (DSP400) is the percent of hours and the percent
of classroom floor area between 8 a.m. and 3 p.m., Monday
through Friday, from Aug. 15 through June 15 when daylight
provides at least 40 foot-candles or more of illumination at a
work plane located 30 inches (76 centimeters) above the
floor. Achieving
a DSP of 400 is an indicator of over-lighting and glare, and
is therefore penalized.Climate Based Next Generation Metrics
x y z DF [%] DA [%] DAcon [%] DAmax [%] UDI<100 [%] UDI100-2000 [%] UDI>2000 [%] DSP [%] annual light exposure
[luxh]
1974.000 -291.960 36.000 4.2 90 95 13 3 41 56 22 10264053
2304.000 -291.960 36.000 3.2 87 93 0 3 53 44 66 7681253
2535.960 -289.800 36.000 3.4 89 94 5 3 49 48 45 8577834
x y z DF [%] DA [%] DAcon [%] DAmax [%] UDI<100 [%] UDI100-2000 [%] UDI>2000 [%] DSP [%] annual light exposure
[luxh]
1974.000 -291.960 36.000 2.8 85 92 0 4 57 39 84 6791708
2304.000 -291.960 36.000 1.2 63 82 0 8 92 0 83 2877087
2535.960 -289.800 36.000 1.6 70 86 0 5 91 4 90 3539914
Land Institute Research Facility, Salina Kansas
100% Clerestory to the South
50% Clerestory to the South
Analysis through HDR imaging (Luminance and Illuminance)
Questions?