By Beatrice K Otto
LIGHT
LET THERE BE LIGHT
Lighting can have a massive impact on well-being, alertness and productivity. Artificial light is also a major source of energy consumption in itself and in the demand it creates for cooling. To improve comfort and reduce energy use, you can:
- maximise the quantity and quality of daylight
- minimise glare from both natural and artificial light sources
- install dimmable lighting with individual controls for personal preference and different tasks
- use energy efficient lighting where possible
Natural, Diffuse Light
Maximise daylighting through windows, clerestories and redirecting systems which can extend daylight deeper into the building than the usual 3-4 metre light perimeter provided by normal windows. This reduces energy use and heat generation, cutting down the need for cooling systems - creating a virtuous spiral of energy savings. Examples include:
Designing the work environment to increase productivity requires first asking employees what they want. Compaq repeatedly surveyed and interviewed its workers to find out how they felt about their current workplaces and what they would like to see in a new facility. The single most common response concerned daylighting. People want as much natural light as possible in their office and would like to be able to see outside.
Joseph Romm, Cool Companies
- light pipes which bring light from the roof to an interior room - they look like ceiling lights, only the light source is solar
- light shelves fitted in windows can reduce glare at the perimeter and increase lighting at the interior, reducing the need for artificial lighting and the contrast of glare and shade which is hard on the eyes. A school in Brazil found that learning improved by about 26% after light shelves were fitted in classrooms, creating evenly diffused natural light.
- shading devices to reduce direct sunlight, glare and heat.
Recreational Equipment Incorporated (REI) believes that the daylighting used in its flagship store results in customers lingering longer, for 1.5 to 2 hours per visit. They have consequently made daylighting a standard feature of all new stores. This applies to refits too: companies which have experimented by refitting one half of a premises to allow more daylight noticed that productivity - and sales - went up in the half with more natural lighting.
Dim the Switch
Giving people control over lighting levels at their desks, in response to different tasks or personal preferences, leads to improvements in accuracy and alertness, and tends to lower overall lighting loads and costs. The tendency is to choose lower levels of light than designers would normally allow for.
California Steel Industries refit 11 workstations in its Drafting Engineering Department. After the upgrade they measured the light levels at every workstation over a 6-day period. Light levels varied with task, age, and personal preferences, but averaged 36-38 foot-candles for computers and 55-57 for drafting - much lower than standard design practice would suggest and much lower than the original levels of lighting. Many used as little as 20 foot-candles for computer work and 30 for drafting work. The personal lighting controls brought overall energy savings to more than 60%.
Joseph Romm, Cool Companies
Energy Efficiency
Choosing energy efficient lighting can have a significant impact on the overall energy use of an office. Sensors can monitor light and occupancy levels so that artificial lighting is never too bright or competing with sunlight, or wasted on empty rooms.
Nobel House, a DEFRA office in London recently refurbished to meet the highest BREEAM sustainability rating (Excellent), uses a solar controlled smart system that dims electric lights automatically as natural light levels rise.
Tax Incentives
The Enhanced Capital Allowance Scheme lets you claim 100% capital allowance in the first year of an energy efficiency investment, including investment in energy saving lighting.
Fun with Factoids
- Lighting consumes about 40% of electricity in commercial buildings.
- Another 10% goes to cool the heat generated by lighting.
- Lighting electricity can be reduced by up to 90%.
WHERE CAN I FIND OUT MORE?
http://www.eren.doe.gov/femp/
The clear, comprehensive Low Energy Building Design Guidelines can be downloaded from the Federal Energy Management Programme website. One of the best overviews of how to reduce energy consumption, including costs, benefits, design and analysis tools, case studies and further resources, with a superb overview of lighting strategies.
http://www.advancedbuildings.org/
This is a superb source of briefings on a range of sustainable building topics including lighting and daylighting. A great place to start learning.
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WHERE CAN I SURF MORE?
TOOLS
http://www.eere.energy.gov/buildings/tools_directory/subjects_sub.cfm This is the mother of all tools, providing a directory to hundreds of tools on building performance, with a section dedicated to lighting systems tools.
http://www.sbis.info/ The Sustainable Building Information System provides knowledge and links to relevant other sources. You can search for documents, methods and tools, people and organisations, projects, policies and programmes, including those on lighting and daylighting.
DAYLIGHTING
http://www.wbdg.org/design/daylighting.php A short, sweet introduction to the benefits and concepts of designing for maximum daylight.
http://windows.lbl.gov/ Has sections on Glazing Materials, Window Properties, and Commercial Performance.
http://www.enermodal.com/Canadian/pdf/DaylightingGuideforCanadianBuildingsFinal6.pdfDaylighting Guide for Canadian Commercial Buildings (August 2002) can be freely downloaded from the website of the Public Works and Government Services of Canada. Fairly concise and readable, it also provides some brief case studies.
http://windows.lbl.gov/comm_perf/Default.htm Links to the Daylighting in Commercial Buildings Sourcebook and Daylighting The New York Times Headquarters Building.
http://windows.lbl.gov/daylighting/designguide/designguide.html Tips for Daylighting.
http://windows.lbl.gov/daylighting/default.htm Considers light redirecting systems.
http://www.eere.energy.gov/buildings/tech/lighting/A straightforward tour of daylighting, under this section on energy efficient lighting.
http://www.sunpipe.co.uk/ The company that produces the Sunpipe, an aluminium light pipe for bringing daylight into a building interior, and the Sola-Vent which combines light piping and solar powered ventilation.
http://www.solatube.com/ Another maker of light pipes, or 'miracle skylights'.
LIGHTING
http://www.wbdg.org/design/efficientlighting.php A short, sweet guide to energy efficient lighting, well illustrated and clearly written. A good starting point.
http://www.wbdg.org/design/electriclighting.php A short, sweet guide to electric lighting controls, such as photosensors and occupancy sensors, which can make a big difference to productivity levels (up) and energy bills (down).
http://btech.lbl.gov/ The Lawrence Berkeley National Laboratory does wide ranging research on windows, daylighting, lighting systems, and commercial buildings systems.
http://lighting.lbl.gov/
They also have a Lighting Research Group addressing these issues:
http://lighting.lbl.gov/lh_main.html The Human Factors research team considers how lighting affects productivity.
http://lighting.lbl.gov/lc_main.html Linked to productivity is the capacity to improve control of lighting. The Control and Communications research is considering how digital technologies can be applied to building lighting controls.
http://www.light-link.com/ Lightsearch is a source for lighting products and manufacturers.
http://www.arc.cmu.edu/cbpd/iw/index.html The Intelligent Workplace has suggestions for lighting and lighting controls.
http://www.eere.energy.gov/buildings/tech/lighting/A straightforward tour of various forms of energy efficient lighting. A good place to start.
http://www.eu-greenlight.org/ Website of the EU's Greenlight Programme, aimed at encouraging more energy efficient lighting. It has an annual award, and also an e-newsletter.
http://www.eu-greenlight.org/What-to-do/Choose-Options/l_all.htm The EU's Greenlight Programme also has an excellent overview of energy efficient lights and a guide to action.
SUPERWINDOWS
http://windows.lbl.gov/ Has sections on Glazing Materials, Window Properties, and Commercial Performance.
http://www.efficientwindows.org/ Provides a wide-ranging introduction to technologies around energy efficient windows and tools for selecting them, including a detailed glossary and access to superwindow information. Although quite US-oriented, it's still valuable to a European.
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