Owens-Illinois Glass Company

Glass Block Reflects Sun's

Rays, Arizona Man Finds

The performance of glass block masonry under sun load and intense summer heat conditions, a problem that has particularly interested architects and builders in recent months, is attracting nation-wide attention in recent weeks since completion of the Barry Goldwater residence in Phoenix, Ariz., the hottest district in the United States.

Glass masonry has been enjoying a spectacular demand since the first of this year, but until recent weeks no residential installations of important size were available for study under solar heat conditions of warm summer months.

Mr. Goldwater's own experiment, therefore, as related in his personal letter to W. P. Zimmerman, manager of the glass block manufacturing division of the Owens-Illinois Glass company at Muncie, Ind., are particularly informative. He says in part:

"There has been quite a bit of comment among builders in this city ever since we used the glass blocks. Most of this comment has been to the effect that the blocks transmitted so much heat that it was impossible to economically cool the house."

"To disprove this, I had two of our leading architects, one of our general contractors, and three other men vitally interested in building out to my house this noon and the following experiment was performed:"

"A thermometer was placed in my living room, which represents an average room in the house and which has no glass block wall area, and a second thermometer was placed in another room containing the glass block wall, which provides natural day-time illumination for our stairway. This thermometer was located about 15 feet from the block."

"We wished to see what temperature could be maintained in the living room as compared to temperature of the room containing the glass block wall. The outside temperature at the time was 90 degrees. Within a half hour we took a reading and both thermometers registered exactly the same."

"This experiment was performed at noon, immediately after the sun had passed over the house, leaving the glass blocks in a semi-shade. I have personally conducted this experiment with the rays of the sun coming directly in on the thermometer, in the room with the glass block wall, and we were able to maintain the same temperature 15 feet from the bricks as was maintained in the living room. To offset any arguments used against this brick as increasing the cost of cooling, I have the following figures to offer:"

"Our house is cooled by a 15-ton refrigeration system and the power company estimated that the cost of operating this system would be approximately $100 a month in view of the large area of glass block. My electric bill for six weeks for the entire house, including lighting and power used in my own machine shop, the power used on an ice water system, in the ice box, and the 15 h. p. m. on the cooling system was $55 and some odd cents. Included in this amount was the gas used in cooking and the hot water heating."

"I thought the above figures might be interesting to you, inasmuch as they do not represent a laboratory test but an actual experience in one of the hottest districts on the face of the globe. I personally feel that it is the most ideal construction unit to be brought out for use in modern homes and residences in hotter countries."

"We are highly pleased with the result and have received many compliments on the appearance of the house. We had more than 180 bricks left over and have since sold them to two different people building homes near us, and have had many more inquiries regarding their use."

In direct contrast to Mr. Goldwater's summer experience, is the statement of George A. Chapman. A. I. A. consulting architect of Chicago made following his visit to the all-glass block building of the packaging research division of the Owens-Illinois in Toledo last January.

"There is no question in my mind but that the building industry has been provided with a new element in design which will be the means to creating a new architecture," he said. "After seeing this building on a day when the thermometer registered well below zero, I am convinced of the entire practicability of glass building blocks."

Various patterns on the sides of hollow glass blocks diffuse light rays and bend them floorward, upward, or straight across the room, depending upon the type of face cutting the occupant wishes. Further, in the manufacture of the block the air in each brick is trapped at high temperature, creating a vacuum averaging 50 per cent, and thus providing insulation against solar radiation.

A glass block wall 3 7/8 inches thick, the approximate depth of a single block, is equivalent to a to a 16-inch un-plastered brick wall or an 18-inch thick un-plastered concrete wall as an insulating medium against non-radiant heat or artificial heating loads. Such block will retard all but 11 per cent of available light or let in as high as 86 per cent, diffused in each instance and controlled by the pattern of the block.