Group 4.C - Skylights 1-3: Introduction to Skylights for Daylighting of Buildings Flashcards
1. Using Skylights for Day-lighting of Buildings 2. The Skylighting System 3. Daylighting Design
Daylight impacts human biological responses and vision. T or F
T.
Some health benefits of daylighting include:
Hint: SVD SAM
SAD reduction Visual Clarity D - Aids in Vitamin D production Sleep patterns improved - Pineal gland Alertness Mood improved
Unit skylights are defined as
Complete factory-assembled fenestration unit of not more than one panel of glass or plastic.
(…installed on a sloped or horizontal orientation primarily for daylighting)
How have skylights (daylighting) been shown to improve student performance in classrooms.
20% higher standard math tests score
26% higher reading scores
Two main strategies for incorporating daylight are:
Side lighting
Top lighting
What is the difference in natural light distribution between side-lighting and top-lighting?
Side-lighting distribution is more abundant closer to the window or light shelf. Top lighting (skylights) can spread light more evenly in a space.
In commercial buildings in the US, what % of floor area is directly below a roof? What does this mean?
60%
60% of U.S. commercial floorspace could benefit from unit skylights.
What does the term “foot candle’ refer to?
The illumination produced by a source of one candle at a distance of one foot.
Equal to one lumen/s.f.
The sky is ___ times brighter straight-up than on the horizon, even on a cloudy day.
Three times.
How much illumination (f.c.) is provided by direct sunlight and blue-sky (away from the sun)
5,000 - 10,000 f.c.
1,000 - 3,000 f.c.
What entity provides recommended illuminance levels for various spaces and uses?
Illuminating Engineering Society (I.E.S)
List the IES recommended illuminance levels (f.c. / l/s.f.) for each space: Warehouse Classroom Retail General Office Library Manufacturing
5-30 l/sf 20 - 50 20 - 50 20 - 50 30 - 50 30 - 75
In a top-lighting context, is building orientation a critical factor?
No.
Unit skylights receive direct sunlight all day long. .
In designing skylighting system some building characteristics to consider include:
Ceiling Ht.
Color of surfaces
Shelving
Partitions.
A properly designed skylighting system works in conjunction with what other building system?
Why?
Automatic lighting controls.
To allow reduction of artificial lighting as daylight levels increase.
In what 4 ways have modern skylights addressed water intrusion issues from site-built skylight assemblies?
Better, factory formed components
Improved gaskets and sealants
Condensation containment
Thermally-broken frame
What standard provides guidelines for effective skylight installation.
AAMA 1607
Cite examples of what aspects of a skylight system are strategically typically considered in the design?
Skylight aperture
Light well
Light well depth
What general aspects of skylight performance are impacted by material selection?
(Hint: DALE)
D Durability
A Amount of Visible light
L Light Diffusion
E Energy Performance
List some glass material options for skylights in terms of glass material quality and surface treatments
Glass:
Quality: Tempered, Laminated
Treatment: Low-E coated, Sand Blasted or chemically etched, Ceramic frit
List 5 plastic and polymer material options for unit skylight lenses:
PAFIM CI
PolyCarbonate Acrylic Fiberglass Insulated panel Molded sheet Co-polyester Impact Modified
List factors that must be considered in evaluating glazing materials:
Visible Transmittance
Haze Factor
SHGC
U-factor -thermal conductance
What does haze factor refer to
The ratio of diffusely transmitted light (>2.5 deg of scatter) to the total transmitted light of a glazing material.
What are NAFS requirements regarding haze?
What standard is referenced?
Max allowed scatter of original light transmittance: 10%
ASTM D1003
Additional considerations in skylighting design (Beyond unit skylight materials) include:
Hint (DWUGS)
(U is a verb…)
Diffusion of light Well design Utilize light-colored surfaces Glare avoidance Size and Spacing of skylight
Why is clear glazing not ideal for skylights?
It creates ‘hot spots’ that travel across the floor
Ways to achieve diffusion and control beam sunlight include:
try for 4 of 6
Glazing properties louvers well shape well diffusers banners shades
Ceilings should be painted ____ and (reflecive or flat) colors as part of a skylighting strategy.
White/light
Reflective
What are the two essential parameters of a skylight well?
Throat
Splay
What are the functions and attributes of a properly designed skylight throat?
To efficiently move light through the ceiling plenum space, between the roof and the ceiling.
Light colored and reflective surfaces to maximize daylight transmission.
What is well splay and what does it do for a skylight installation.
Splay is the angle in the walls of the throat or skylight well.
It allows light to spread as broadly as possible and reduces glare.
What are the three zones of a Tubular Daylighting Device and what does each do?
Capture - The optical dome, collects light
Transfer - optical tubing - redirects and transfers light
Delivery - optical diffuser - spreads daylight into the space.
Where are TDD’s best used?
Smaller rooms like hallways and bathrooms
List some emerging technologies being applied to daylighting systems:
Hint (ASS SH)
Aerogel filled wall glazing panels Spectrally selective technology Smart surfaces Switchable Photochrome Heliostat arrays
Quiz Notes Skylights, Part 2:
Examples of plastic glazing materials
Use of ASTM D1003
Light well shape
TDD function
What general factors determine skylighting illumination uniformity?
Glazing properties
Skylight spacing
Room geometry
(& well design)
What are the uses and limitations of calculation (SkyCalc, Excel) programs in determining optimal sky lighting layout for buildings?
SkyCalc is limited to modeling simple diffusing skylight scenarios and calculating average energy savings. It cannot be used to estimate performance of modern optical day-lighting systems.
SkyCalc can model interactive effects with daylight control and HVAC systems, occupancy schedules, photo control algorithms to determine average energy savings. T or F?
True.
Yes, I just wanted to get these facts into the cards.
Input fields for SkyCalc include:
Size: Length, width and height of the space Lighting type Daylight control system HVAC systems Storage racks Ceiling color Energy Cost
With many trade-offs involved, several factors inform the decision between a ‘more but smaller’ and ‘fewer and larger’ approach to sky lighting design for a space of given size and skylight to floor ratio. These include….
Height of space Use of space (tasks) Daylighting needs Structural constraints Cost constraints
What is one basic rule of thumb for skylight spacing, to achieve uniform diffused light throughout a space?
- 0 to 1.5 times the ceiling height, center to center will work.
* This obviously would vary a LOT with the size of the skylights.
Beyond a certain Skylight to Floor ratio (SFR), adding more skylights impacts___ & ___ costs, offsetting savings in lighting costs
Heating and Cooling.
Increased costs for skylights and installation cost also tilt the cost balance.
The air conditioning load for 100,000 lumens of light (30-40 fluorescent lamps) for the following lighting options:
A. Incandescent light
B. Fluorescent lamps
C. Shaded daylight
A. 1.9 tons
B. 0.63 tons
C. 0.27 tons
Typical cooling load for shaded daylight illumination is what % of that for incandescent lighting?
About 14%
Energy savings that accompany sky lighting are realized when a _____ system is installed to monitor and control ____.
Daylighting control
Electric lights.
Lighting control strategies use tow main options. What are they?
Open loop
Closed loop systems
An open-loop control system for lighting control senses light inputs from _____ illumination sources only.
(Think about what is left out of an ‘open’ loop, vs. a closed loop in logic/programming)
Daylighting.
An open loop control system is best for which of the following lighting controls?
A. On/off
B. Dimming system
C. Stepped-level
A and C
Open loop systems are problematic for dimming lighting controls
A closed loop control system responds to light levels from _____illumination sources.
All.
Which control system type should be used when dimming control is desired to maintain optimal illumination?
Closed loop.
Electric lighting control options for daylight management systems include:
On/off
Multi-level switching
Dimming.
Do we really need a card to quiz on the “on/off” option for lighting control?
No. Clearly it means the lights are turned off when a given illumination threshold is reached.
Multilevel switching works by
A. Stepping down the lighting levels from all fixtures at once.
B. Fully shutting down portions of the electrical lighting in stages.
C. Putting switches on different levels in the space.
B.
C? Come on - don’t be like that.
Dimming lighting control works by:
A. Using ballasts or specialized switches to gradually reduce light output from all controlled lighting.
B. Pulling shades over the lights to reduce illumination.
C. Going outside.
A.
Though you may feel that C is a good option for you right now.
What is the primary reason for reported problem with automatic photocontrols?
Manual interruptions of the system - occupants turning the lights on/off manually.
Studies find that photocontrols save __ % of the predicted savings. These savings depend on correct ____ of the system.
97%
Commissioning
California Title 24 establishes prescriptive requirements for skylights and photocontrols based on certain ___ and ___ of the project.
Area and Ceiling height
This standard limits skylight area and includes requirements for lighting controls and visible transmittance:
ANSI/ASHRAE/IES 90.1
Other skylight design considerations that may be regulated by local building codes include:
Energy efficiency (U-factor, SHGC, and VT) Hail impact Ice and Snow Miami-Dade (Hurricane) Flame and Smoke Requirements
Where can we find U.S. Department of Energy guidance on how to select lighting controls for offices and public buildings?
Try this:
https://www.energy.gov/sites/prod/files/2013/10/f3/light_controls.pdf
Can SkyCalc be downloaded for free?
Yes.
http://h-m-g.com/downloads/SkyCalc/sky30_download.htm
Q1. The air conditioning load for 1000,00 lumens of light from fluorescent lights is ___ tons?
a. 0.27
b. 0.63
c. 1.73
d. 1.90
b. 0.63
Q2: In a closed loop lighting control system, the photosensor will typically be placed:
a. On the ceiling looking down
b. Face upwards looking out of the skylight
c. Mounted on the outside of the building
d. Face downward on the outside of the skylight.
a. on the ceiling looking down.
Q3: With this type of lighting control, all of the controlled lamps are turned off when there is adequate daylight.
a. multi-level switching
b. dimming
c. on/off
d. shaded daylight
c. on/off
Q4: Which on of the following codes limits skylight area and includes requirements for lighting controls and visible transmittance?
a. ASHRAE 90.1
b. IgCC
c. California Title 24
d. IECC
a. ASHRAE 90.1
Does the FGIA offer more resources related to skylight design?
Yep.
https://fgiaonline.org/pages/skylight-sloped-glazing
Can the Modular Skylighting Guidelines be helpful in addressing challenges for skylights with suspended ceilings?
Probably. This course says so.
https://h-m-g.com/Projects/skylighting/modular_skylight_guidelines.htm
There are two Sound Transmission Loss performance measurements; _________ is used for rating exterior walls and facade elements, while _________ provides a rating for interior building partitions.
STC
OITC
Exterior walls: OITC - Outdoor-Indoor Transmission Class
Interior partitions: STC - Sound Transmission Class
