|In 1977, MechoSystems received a complaint that the shades in a project were not providing the appropriate amount of solar protection. People complained of overheating, glare, etc. We followed through on the complaint with the architects and then with the HVAC contractor, then with the mechanical engineer. All elements were in accordance with known norms and standards at that time. There was no scientific justification for the problem, but the problem was there.
We were put in touch with Prof. John Yelliott of Arizona State University. Professor Yelliott did the work that was used in the design of building A/C systems and had developed the concept and test protocol of heat flow through fabrics for ASHRAE. This work by Prof. Yelliott was the basis of all heat flow algorithms used in ME design for calculating heat flow through a glass-and-shade assembly.
Prof. Yelliot quickly pointed out that the problem with our project was that the fabric was too open and allowed too much direct solar radiation to penetrate the shadecloth. Thus the people in the “sunshine” were over heating. It is not surprising that thermostats are located far from the window-wall, completely away from direct sun, and thus sense only air temperature changes. They react to air temperature changes only, and if placed (like people) near the window and in the sunlight, they would require the A/C system to run nonstop.
As a result of this discussion and detailed review of the mechanical engineers' formulas, we determined that more scientific research was needed to define the perimeters for personal comfort with a window shade device. Professor Yelliott suggested (and we accepted his recommendation), that we also include visual tests for glare and brightness.
During this period, HomeCraft Drapery was selected as the contractor to supply draperies to the New Arizona Bank Tower, also in Phoenix, Ariz. Professor Yelliott knew the developer very well and HomeCraft Drapery had a very good rapport with the bank. The top floor was unrented at the time.
At our request the developer allowed Prof. Yelliott to use the floor as a solar test site. We proceeded to install different types of glass into each window on the west facade, and set up test rooms (one per window) to measure the heat flow, radiant energy, and luminance through different types of shade and glass combinations. The developer allowed us to temporarily remove and replace the building standard glass and reinstall new glass of different types in order to measure the difference.
The aforementioned tests were known as the Arizona Test of 1978. The results of our testing were the development of an entire new range of denser shadecloths, in medium and darker colors to complement the visible (daylight) transmission of the glass. We established guidelines and recommendations for the use of our shadecloths, and now offer the broadest range of shadecloth color and density of any company worldwide.