Daylighting Always A Compromise

Daylighting is always a compromise. How much light do you need vs. how much solar heat gain can you accept.

When considering a daylighting system there are three main performance measures.

  1. Light Transmission
  2. U Factor
  3. SHGC

The more light transmission you require will result in more solar heat gain. Reducing light transmission to reduce solar heat gain is not always the best trade off. A daylighting model may be necessary to determine the appropriate light level.

CPI LogoIn our research and experience, the best product for currently on the market is UniQuad by CPI Daylighting. UniQuad has the best light transmission percentage to solar heat gain in the industry. Coupled with Skylight Specialists Inc, they can also provide assistance with daylight modeling and studies.

UniQuad vs. Non-Removable Skin Systems

Not all daylighting is created equal! Glass, fiberglass and other non-removable building envelopes can’t compete with the UniQuad system.

Daylighting Technology Visible Light Transmission NFRC-100 Center of Glass U-Value
Glass (Clear/Dbl Glazed, 90% Argon Filled) 79% 0.48
FRP (Crystal/Crystal w/batt insulation) 30% 0.29
UniQuad (Clear Matte/Clear Matte, Air Filled) 50% 0.23

The UniQuad system is the best of both worlds – it will give you up to 50% LT with a U-Value of 0.2

How Daylighting Impacts Our Productivity

Increase Your (Or Your Employees) Productivity with Proper Lighting and Temperature

Daylighting has many benefits, and while most companies and studies focus on cost reduction, daylighting can have a more subtle, yet equally important benefit for yourself or your company.

People who work in natural daylight work more effectively, work longer, feel healthier and happier by the end of the day.


9386-7901Most people notice the difference between daylight and artificial light (think about working another day in the office, or spending the day outside) but typically don’t equate it to natural lighting.

A recent study by Mirjam Münch (and others) compared the two environments and recorded how performance, sleepiness, and hormonal activity. They studied two groups of people, one worked in natural daylight, the other in artificial lighting for 8 hour periods. Their results:

Subjects felt significantly more alert at the beginning of the evening after the DL (daylight) condition, and they became sleepier at the end of the evening after the AL (artificial light) condition. For cognitive performance we found a significant interaction between light conditions, mental load (2- or 3-back task) and the order of light administration.

4325_Foothills_Academy_PIn other words, even after just one work period, people felt more awake at the end of the work day (and through it) and slept better that night when working in natural daylight versus artificial light. They also performed better, especially on more difficult tasks, in daylight than artificial light.

One more important finding is that our cortisol levels drop significantly under artificial or poor lighting conditions. Cortisol controls our stress and energy levels, losing it prematurely means you are more tired and stressed throughout the day.

To put it briefly, spending the day in dim or artificial light makes us sleepy, less productive and stressed. This can be powerful knowledge to have in home and office design. Paying attention to your and your employees rhythms and needs can improve your and their productivity and make the place a more enjoyable environment.

Saving Energy With a Good Daylighting System

Properly designed daylighting systems save energy and costs

Artificial lighting requires large amounts of energy and can represent as much as 50% of the electricity consumption of a building. Artificial lighting also generates a large amount of heat. When a good daylighting system is considered in the design phase the HVAC system can be reduced in size and operational cost will be lower.

Replacing artificial lighting systems with an effective daylighting system can reduce a building’s energy costs by as much as 30% to 70%. It is essential that lighting controls be utilized in a good daylighting system.  If the artificial lights are not turned off when the appropriate light levels are met the daylighting system is probably not saving any money on energy.

There are skylight manufacturers that tie the available daylighting into the lighting controls to always insure correct amounts of light and at the same time manage costs to avoid waste.