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. In the EU, indoor lighting uses some 14% of electricity in commercial buildings, and in the U.S. 37%, yet the IPCC (Intergovernmental Panel on Climate Change) reckons that lighting energy use can be reduced by 75-90%. 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
  • use light colours for walls and other surfaces to reduce the need for artificial lighting

Natural, Diffuse Light

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

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:

  • 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. Consider, for example, automatically switching off main lights in an office after a certain time in the evening, so those working late use personal desk lights.

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 on average were much lower than standard design practice would suggest and much lower than the original levels of lighting. The personal lighting controls brought overall energy savings to more than 60%.

Joseph Romm, Cool Companies

Energy Efficiency

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.

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.

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%.