This article discusses how to control direct and indirect glare caused by sunlight in green houses and sunspaces.

Advice for Insulating a Greenhouse or Solarium Against Night Time Heat Loss

The accompanying text is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

Our page top photo shows a sunspace constructed by the website editor and an example of indirect solar glare (to the right of the plant in our photograph).

Beating Sunspace or Greenhouse Glare in buildings

• Usual sources of complaints of solar glare: long term exposure
• How to reduce or control solar glare in greenhouses and sunspaces
• Seasonal vs. year-round control of solar light glare in buildings
• Rearranging room contents to eliminate solar or sunlight glare
• Use of supplemental lighting to reduce indoor glare effects
• Use of solar shades or blinds to control or reduce sunlight glare indoors

Question: what strategies are most promising for controlling indoor glare from sunlight or other sources?

A building we own and occupy has a three-story atrium/sunspace with over 30 2x5-foot windows. Our computer room faces the atrium and users complain about the glare.

We are considering installing shades or films to control the glare from sunlight. What solar glare strategies are most promising? - Lou Nemesec, Illinois Industrial Commission, Chicago IL

Answer: Solutions to Sunlight and Indoor Light Glare 

Glare can interfere with vision and cause discomfort, eye fatigue, and over time, eye damage, even contributing to cataract formation where UV wavelength light is also present.

Types of Light Glare: Indirect & Direct

There are two kinds of glare: direct glare and indirect glare.

Direct glare is caused by light coming directly into the eye from the light source.

Indirect glare is caused by reflected light (see our photo at page top).

Strategies for Controlling Glare in buildings

As we elaborate below, you can control glare and reduce glaring light complaints in buildings by one or more of the following six methods:

• Reducing the brightness or size of the light source
• Changing the position of the light source
• Making the area around the light source brighter
• Rearranging furniture and seating positions to change the relationship between the light source, work surface, and worker
• Reducing the contrast between incoming light and surrounding surfaces
• Adapting glaring light control to seasonal changes in sunlight

You can control glare by reducing the brightness or size of the light source, changing the position of the light source, or making the area around the light source brighter.

We assume that the complaints about glare come from long exposure, since short term exposure to glare can usually be tolerated. We also assume that you can't rearrange the building or room to change the relationship between the light source, work surface, and the workers themselves in order to change the angles of light and light reflection to simply eliminate the problem.

The size of the light source in your building too is fixed, unless you block out some of the entering sunlight with an opaque material.

So what measures are left to reduce indoor glaring light problems?

You could reduce the contrast between the incoming light and the surrounding surfaces by increasing the lighting level on the interior surfaces with electric lighting.

But it seems that your best bet is limiting the brightness of the light source.

If you need year-round help, use window films. Window films can cut out anywhere from 45 to 86 percent of the incoming light. If view is not important, permanent louvers may do.

If you want seasonal control over glaring light, use movable or removable shades or blinds. Interior choices for glaring light source control include vertical or horizontal blinds.

External choices for glaring light control include woven fiberglass shades or aluminum mini-louvers.

Details about solar shades are found at

 SOLAR SHADES & SUNSCREENS

and SOLAR SHADES, LOW-E EFFECTIVENESS.

The original article below [PDF] is expanded and illustrated above:

• Q&A: Beating Sunspace Glare for Greenhouses or Solariums - PDF version; use your browser's back button to return to this page. Original article, Solar Age Magazine, October 1985, adapted and updated for InspectAPedia.com December 2010.

The question-and-answer article on this pate paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss. Solar Age Magazine Articles on Renewable Energy, Energy Savings, Construction Practices

...

Continue reading at SOLAR SHADES & SUNSCREENS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• GLASS vs HEAT MIRROR SOLAR GAIN/Loss
• GREENHOUSE DESIGN for SOLAR HEATING
• GREENHOUSE or SOLARIUM INSULATION
• GREENHOUSE / SUNSPACE GLARE
• PATIO AWNING INSTALLATION
• SOLAR COLLECTOR FILMS - performance of films to increase solar collector efficiency
• SOLAR GAIN CALCULATION
• SOLAR SHADES & SUNSCREENS
• SOLAR SHADES, LOW-E EFFECTIVENESS
• SPONTANEOUS GLASS BREAKAGE NiS
• SUNGAIN, FILMS, LOW-E GLASS - use of Sungain film on windows and window film selection and installation
• SUNSPACE GLAZING for SUNTANNING
• WINDOWS & DOORS, AGE, TYPES - home

Suggested citation for this web page

GREENHOUSE / SUNSPACE GLARE at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to SOLAR ENERGY

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Citations & References

In addition to any citations in the article above, a full list is available on request.

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