Natural lighting boosts retail sales -- at least it did in 1999!

I was browsing the Web, following interesting links, and I came to a company -- Entech Solar -- that makes skylights for commercial businesses. And that led me to a link at the bottom of that page, on Skylighting and Retail Stores. (If you want to read the report, you have to go there and click on the link yourself, since I was unable to embed it.)

That research report, in PDF format, had some interesting results, including these:

Skylights were found to be positively and significantly correlated to higher sales. All other things being equal, an average non-skylit store in the chain would likely have 40% higher sales with the addition of skylights, with a probable range between 31% and 49%. This was found with 99% statistical certainty. After the number of hours open per week, the presence of skylights was the best predictor of the sales per store of all the variables that we considered.

and also

Informal interviews with shoppers repeatedly confirmed that the vast majority of shoppers were not aware of the skylights. The questioner, looking just like any other shopper, would approach a shopper and ask: “May I ask you a question?” The response was universally affirmative. We then asked, “What do you think of the skylights in this store?” The typical response was to look up, look puzzled, and then say, “That’s funny. I never noticed them before.” Out of 42 interviews in 10 skylit stores, only three shoppers could be found who were already aware of the skylights. Two of those volunteered that they had only noticed the skylights because their small child had pointed them out on an earlier trip, while looking up at a balloon or other bright object.

and also

A store with skylights is observed to have a sales index higher than an equivalent store without skylights. This is clearly the largest effect of any of the variables considered, (at B=+1.55). It is possible that there may be other reasons that the skylit stores are performing so well as a group. In our site visits, we made every effort to try to identify other characteristics of the skylit stores that might contribute to higher sales, but we did not find any obvious candidates. However, that possibility should always be kept in mind when examining these results.

and this

These results show that adding skylighting to the average non-skylit store within the chain would be likely to improve its performance by 40%, with a probable range somewhere between 31% and 49%. Thus, if this non-skylit store were averaging sales of $2/SF, then its sales might be expected to increase to between $2.61 and $2.98 with the addition of a skylighting system.

But here's the biggest caveat -- the study was conducted in 1999! Ugh. I have a call in to the research company, and I'll post any updates I hear about. The research was sponsored by the utility company PG&E, which encourages me, since a utility company would not, I think, preferentially seek out research that suggests decreasing electricity use. Food for thought.