Radiant Temperatures in the Sunspace:
Hypothesis, Methods, Data, and Analysis

Hypothesis

As mentioned earlier on the hypothesis page, we believe the sunspace will exhibit extreme radiant temperatures which will act in parallel with high and low ambient temperatures to create uncomfortable conditions.

Method

In order to judge the cumulative effects on comfort of both ambient temperature and radiant temperature, we decided to record both simultaneously and compare them graphically. We measured the extremes of the radiant temperatures in the sunspace by placing a temperature sensor inside one of the skylights so it would receive constant sunlight. In order for this sensor to record radiant temperatuires without being affected by ambient temperatures, we covered its thermistor with a ping-pong ball painted gray. This eliminates some of the airflow around the sensor, and approximates the color of human skin to more accruately reprsent the radiation effects. We then plotted this data along with the ambient temperature data to try to get a feel for what comfort in the sunspace would be like.

Data and Analysis

This graph compares ambient and radiant temperatures in the sunspace (11 k gif)

The data from the ambient temperature sensor and the radiant temperature sensor are plotted above.

As expected, the radiant temperatures reach extreme levels at the high and low peaks. For most of the day, these strong radiant temperatures, in combination with the high ambient temperatures, produce uncomfortable conditions in the sunspace. On the high end of the scale, the peak radiant temperatures routinely rose above 100 degrees fahrenheit during this February week. On the low end, the radiant temperatures dropped down to around 50 degrees fahrenheit. Brrr.

Conclusions

The radiant temperatures in the sunspace are extreme enough to have a strong impact on comfort in the space. This is especially true because they act in parallel with the ambient temperature in the space. When the air temperature is high, the radiant temperatures are also high, and when the air temperature is low, the ambient temperatures are also low. This phenomenon causes both overly hot and cold conditions. For the Siegels to make this sunspace into a part of their house where they can spend much of their day will require some major modifications to mitigate the effects of all that glazing.

Comments to author: vitalsigns@
ced.berkeley.edu

All contents copyright (C) 1998. Vital Signs Project. All rights reserved.

Created: 04/23/96
Revised: 09/09/02

http://www-archfp.ced.berkeley.edu/vitalsigns/workup/siegel_house/sgl_rad.html