HUMAN PERFORMANCE BENEFITS
The cost of people in buildings is often 75 - 100 times greater than the cost of utility bills. Even a small increase in employee productivity can far exceed the building's energy costs.
Prior to Edison's development of a practical, commercially available electric lighting system, people spent most of their waking hours outdoors. With artificial light now available 24 hours a day, this has changed dramatically in the last 100 years. We now spend most of our life inside under the wrong light conditions.
Studies began emerging in the 1980's showcasing the powerful human health and productivity benefits of using daylight for illuminating commercial buildings.
Steve Ternoey, a respected author and principal of LightForms, LLC, a California architectural firm specializing in daylight design estimates that, "the cost of people in buildings is often 75 - 100 times greater than the cost of utility bills".1 These figures suggest that the savings gained from even a small increase in employee productivity can far exceed the building's energy costs.
According to Carnegie Melon University's Intelligent Workplace design studio, cutting energy use in half in a typical building usually saves about $1 per square foot. Boosting productivity in that same building by 5% saves more than $10 per square foot.2
Respected companies like Herman-Miller have seen the future of daylighting as common and designed manufacturing facilities that dominantly use daylight for interior illumination. In-depth studies are in progress but early reports show significant drops in absenteeism, lower amounts of turn-over and higher over-all productivity.
Ciralight has developed a tool to calculate the return on payback and investment, based on business optimizing variables affected by daylighting. Typically, the return on investment through energy savings alone is generally 15% to 35% or more, depending on a number of factors (% sunny days, latitude, cost per kWh, days of operation, tax rate, government or utility rebates, peak kWh rates, etc.). However, once additional components such as increased productivity and reduced absenteeism are factored in, actual ROI's can easily eclipse this.
References:
1: 20-Year Cost of Owning and Operating an Office Building
Source: Ternoey, S.E. et al, The Design of Energy Responsive Commercial Buildings, John Wiley & Sons, 1985
2: The non-profit Center for Energy &Climate Solutions' Cool Companies website, www.coolcompanies.org, 2002.