Opening a new window on daylight

Jul 31, 2009

A new approach to windows that could let in more light and cut indoor lighting needs by up to 99% in buildings in Tropical regions without losing the cooling effect of shades. Details are reported in the International Journal of Engineering Systems Modelling and Simulation this month.

Lerdlekha Tanachaikhan and colleagues in the School of Environment, Resources and Development, at the Asian Institute of Technology in Pathumtani, Thailand, explain that electric lighting is typically responsible for 25 to 40% of total in air-conditioned buildings. These figures could be reduced significantly they say if daylighting were used instead.

In Tropical regions, however, daylighting leads to a significant rise in temperature, which has to be countered by air-conditioning if the occupants are to remain cool and comfortable. This in turn consumes about 80% of the total electricity consumption for the building.

Earlier studies on daylighting in buildings indicate that window designs and positioning are as diverse as buildings themselves and none currently provides a satisfactory answer to saving on the lighting bills without pumping up the air-conditioning.

The team has developed a formula for tropical sky climate conditions that allows them to assess different window configurations for daylighting. The formula takes into account glass type, solar and visible light transmittance and reflectance, shading coefficient and the heat value, U.

The formula shows that for a city, such as Bangkok, the potential for daylighting is high and could cut daytime electric lighting requirements significantly. The team suggests that for more than 95% of the occupancy period of a typical office building, daylight alone would suffice for lighting with the appropriate window configuration.

This saving would not be reduced significantly even with the use of vertical fins for east-facing windows and horizontal canopies for south-facing windows to reduce heating effects. Daylighting and shading effects can be optimized by following their formula and choosing appropriate windows size and positioning as well as other parameters, such as glazing transmittance.

More information: "Daylighting for energy conservation in the tropics: a study on the influences of window configurations and shading devices" in International Journal of Engineering Systems Modelling and Simulation, 2009, 1, 144-159

Source: Inderscience Publishers (news : web)

Explore further: First of four Fukushima reactors cleared of nuclear fuel

add to favorites email to friend print save as pdf

Related Stories

New ballast dimming switch developed

Apr 20, 2006

U.S. scientists say they've developed a simple, cost-effective, energy-saving device designed to "harvest" daylight automatically.

Universal Display to Develop Novel Smart Windows

Jan 20, 2005

Universal Display Corporation, a leading developer of organic light emitting diode (OLED) for flat technologies for flat panel displays, lighting and other opto-electronic applications, announced today a $130,000 cooperati ...

Purdue studies office building power

Jan 18, 2006

Purdue University engineers say they've developed a method of "pre-cooling" small office buildings, cutting energy consumption during times of peak demand.

Keeping cool using the summer heat

Jan 23, 2009

(PhysOrg.com) -- While most Australians are taking care to shield themselves from the harsh summer heat, scientists from the CSIRO Energy Transformed Flagship are working on ways to harness the sun’s warmth ...

Recommended for you

The state of shale

Dec 19, 2014

University of Pittsburgh researchers have shared their findings from three studies related to shale gas in a recent special issue of the journal Energy Technology, edited by Götz Veser, the Nickolas A. DeCecco Professor of Che ...

Website shines light on renewable energy resources

Dec 18, 2014

A team from the University of Arizona and eight southwestern electric utility companies have built a pioneering web portal that provides insight into renewable energy sources and how they contribute to the ...

Better software cuts computer energy use

Dec 18, 2014

An EU research project is developing tools to help software engineers create energy-efficient code, which could reduce electricity consumption at data centres by up to 50% and improve battery life in smart ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

RayCherry
not rated yet Aug 05, 2009
Finally! Brilliant.

Even in southern Europe people maintain their (modern) homes in darkness during the heat of the day to reduce the costs of air-con, but they still need lighting which consumes energy.

Better still would be the window that converts heat to electricity while permitting comfortable visible light to pass through. Of course, these same windows must keep warm air inside the building during the winter, but that should not be a problem.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.