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What is It?
Sustainable lighting integrates natural lighting (daylighting) and highly efficient electric lighting systems to create an ultra-efficient and healthy illumination system for a building. The rationale for this type of lighting system is to allow the earth's natural systems (e.g. the sun) to do as much of the lighting work as possible. Only when they cannot meet the required illumination levels are high-efficiency electric lighting systems used to supplement the lighting. We expect the assistance of electric lighting to be needed for less than 20% of the year.
A Sustainable Lighting system can include:
- Daylighting with properly designed windows, skylights, solar tubes
- High-efficiency electrical lighting for space and tasks
- Controls for integrating daylighting and the electrical lighting
Also known as: sun lighting, natural lighting.
Why is it Important?
In commercial buildings, lighting typically accounts for 17 - 20% of the energy usage, second right behind the energy demands of heating and cooling. Any net-zero based energy design needs to address lighting in the early stages of design.
Sustainable lighting is important because it:
- Reduces energy use and carbon footprint from use of electrical lighting.
- Reduces internal heat gains from electric lights that increase the need for cooling in the summer.
- With properly designed thermal windows, it does not add significant heat gain to a space.
- Makes occupants happier, healthier and more productive.
When to Use It?
It is appropriate to use this lighting strategy (especially daylighting) when:
- The building has access to daylight. With limited daylight comes limited benefits, although there would be some. For example, if a building is completely blocked by trees or another building the potential for natural lighting will be greatly diminished.
- Lighting is a significant component of your energy usage.
- Start right up front in the planning phase...this gets very difficult, if not impossible, if done late in the building process.
Green Garage Use of Sustainable Lighting
The lighting sustainability goals for the Green Garage are:
- Connect people with the natural elements...in this case the sun. When clouds move over the building it will naturally become slightly darker, as one would expect.
- Meet at least 80% of our lighting needs through natural daylighting.
- Reduce energy demand for lighting by at least 80%, with an equal reduction in carbon.
- Create a healthy environment for the building occupants.
Strategy and Conceptual Design
Sustainable Lighting Strategy
This strategy really drove the entire design process and the conceptual design that resulted from it. Our sustainable lighting strategy is:
- Only place light where it is needed, when it is needed. Environments are often lighted everywhere at the same level, even if there is no need. This gives the environment a sterile look. This supports Christopher Alexander's (Tapestry of Light and Dark pattern (#135)) recommendations. (See his book, A Pattern Language).
- Design windows to maximize daylighting.
- Tall windows allow light to penetrate farther into the building. Light extends horizontally 2.5 times the height of the window.
- Flared interior window openings let more light in for the given window size.
- Place windows to maximize light where it is needed on the interior.
- Use of Solatubes.
- Provide minimum electrical lighting necessary for times when natural light is not sufficient, both indoor and outdoors.
- Maintain 10 fc minimum in all occupied areas.
- Use high efficiency electrical fixtures (e.g. induction, LED or T5/T8)
- Use step down and occupancy controls.
- Have emergency lighting integrated with regular lighting / PV system
- This minimizes the points of failure and you have higher quality lighting.
Sustainable Lighting Conceptual Design
Daylighting means primary use of the sun to light the interior of a building for human activities. This is accomplished by strategically placing windows, skylights and reflective surfaces to provide the lighting levels needed by occupants of the building. Studies have shown that people are happier, healthier, and more productive when provided with ample natural light. The energy savings provided by using daylighting is also significant.
See the details of our daylighting conceptual design on the Daylighting pattern page. It includes the window and solar tube designs.
- High Efficiency Task Lighting
We're still in the process of determining our lamp and fixture selections for task lighting. We're expecting that every desk would have a task lamp. This would be about 30 lamps. The lamp would only be used when needed. The lamp brightness would vary by the task of the person (e.g. working at a computer versus reviewing fine printed graphics). Tasks requiring less light would get a dimmer (lower wattage) bulb. The lamp would provide the brightness (lumens) required at the lowest wattage and longest bulb life possible. Our target is to keep each lamp below 10 watts. It is possible that this would be powered by DC. should each lamp be dimmable? peoples task lighting needs will vary
- High Efficiency Space Lighting
We're still in the process of determining our lamp and fixture selections for space lighting. We're expecting that on the interior we would ensure that all areas of the building being used are lit at a 10 footcandle minimum. The daylighting would be our first means of meeting this demand. If it can not meet the demand, then high efficiency space lighting would provide the illumination. Currently our position on the space lighting to use is:
- Induction lighting fixtures for the studio workshop area, mounted near the ceiling. See vendors below.
- Induction, T8 or LED for lighting the office area.
- Controls that have the electric space lighting measure the interior brightness of the daylighting and when it drops below 10 fc then the electric space lighting would go on. W and, the possibility, of having the LED or induction come on at a 50% level to supplement the daylighting if that's all that is needed.
- Space lighting integrated with the Solatubes. We were told this is being developed by Full Spectrum Solutions working with Solatube.
Our target is to keep each lamp below 10 watts each. It is possible that this will be powered by DC.
- High Efficiency Exterior Lighting
We're still in the process of determining our lamp and fixture selections for outdoor lighting. We're expecting that on the exterior we would ensure that outdoor areas of the building and site being used are lit at a 1 footcandle minimum. These areas include:
- front parking lot
- front, side and back entrances
- alley lighting
Our going in positions on the exterior lighting are to use:
- Induction lighting fixtures for all exterior lighting. Induction lighting is twice as efficient as an LED bulb and has twice the life expectancy. See vendors below.
- Controls: Have the exterior lighting come on with photocells and step down the brightness (and energy use) after 1am.
- Have the lighting connected to motion detectors in back and front so bright lights come on (or step up) when motion is detected.
Our target is to keep each lamp below 10 watts each. It is possible that this would be powered by DC.
Integrating sustainable lighting with the other building components does require significant thought. Some of the controls will be manual (even behavioral) and some will be automated. The key integration areas are:
- with occupancy controls
- between the daylighting and the high-efficiency electric lighting...only using energy when needed ...indoor and out.
- integration with the PV system (To Be Defined)
The detailed daylighting calculations are shown in pages included here. We thank Jamie Pachla for her great contributions to our understanding of how to work with daylighting through a better understanding of the interrelationship of our design with the lighting effects through her photometric modeling.
Proposed Materials / Suppliers
- Solatubes lighting - 750 DS is the product. Questions for the Solatube rep's visit 02/03/09.
- Full Spectrum Lighting Solutions - Jackson MI...here's the induction lighting performance page.
The Sustainable Lighting - Development Story page contains many images and videos documenting the process used at the Green Garage to design, build and operate our daylighting conceptual design.
Related Internal Links
- Sustainable Window Design
- Energy Modeling
- Sustainable Interiors
- Electrical 2.0 Design Center
- Space Lighting Comparison
- Human Factors/Benefits of Windows and Views
- Overall Daylighting Strategies
- Daylighting Dividends definative guide to daylighting...all the resources in one spot.
- Tips for Daylighting Best indepth guide on daylighting
- Excellent summary of Design Guidelines...recommends the two window strips
- School Daylighting Design Guide ...the best guide for what we need.
- Daylight Dividends Resource Center
- California High-Performance Daylighting Guidelines
- Nice Report on Lessons Learned ...look at second half.
- DOE Daylighting Design Guide ... great for rules of thumb
- Daylighting Experts
- Daylight Modeling
- Light bulbs
- Light Bulb page of Great Lakes Green Initiative...for those that like the details.
- Link to google spreadsheet
- Jamie's data
- Short Video
- Upload images onto Development Story page
- Image for top of page?
- Isn't T8 a bulb size? Not a lighting type?
Peggy edited this page :)