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Stylized Text: ZEH: Lakeland, Florida.

Preliminary Measurements of Comparative Cooling Performance

Plotted below are the comparative AC loads and interior temperature at the PVRES and Control homes over the first four days with both systems set into cooling mode (April 23rd - 27th, 1998). The thermostats were both carefully set to maintain 72oF inside. Since the temperature in April in Central Florida is mild, we set the thermostats artificially low to attempt to emulate the temperature differences that will be seen during warmer weather.

The PVRES home maintained an average interior temperature of 71.5oF against 70.8oF inside the Control home. The main reason for the lower temperature in the Control home was that the nighttime temperatures fell lower without the better wall and window insulation levels-- note that during daytime hours the 4-ton AC at the Control home had difficulty keeping up with the load. The total AC consumption (compressor and air handler) was very different: an average of 19.57 kWh/day in the Control home against 1.79 kWh/day in the PVRES home. The AC consumption in the PVRES home was lower by more than an order of magnitude!

Here is data for the Control home (RED is AC power; BLUE is the interior air temperature):

Picture of Graph.

And here is the same data for the PVRES house (ORANGE is AC power; GREEN is interior air temperature):

Picture of Graph.

Likely, the differences seen here will not be as large during the hot days of summer. Also, the differences are certain to be less when the homes are occupied and have internal loads. Regardless, these results show that we can engineer homes for Florida which use a fraction of the cooling energy relative to how we build now.