Data Log for the Roper Solar Greenhouse
215 Maywood Street, Blacksburg, Virginia
April 2011

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Monthly weather data

It is desirable to compare the YSGH operation temperature data to the external temperature data. Since there is not a mini-weather-station at the YSGH, the daily high and low temperature data taken at the Blacksburg VA National Weather Service Office are used for comparison. The distance between the weather station and the YSGH is about four miles.

Air temperature, humidity, light intensity and CO2 concentration behind the center post

The green-data axis is on the right with the blue data.

Blacksburg VA temperatures, Wind & Sunshine

The units for wind & sunshine are arbitrary. Sunshine really means cloud cover in tenths of the sky.

Heat Sink Energy

The daily cycle of energy being stored in and taken out of the heat sink is obvious. This calculation is not very accurate because the temperatures at the inlet and outet at the two ends of the RSGH may differ even when the heat-sink fan is not on. (The energy calculation involves temperature and relative humidity at the heat-sink outlet and inlet.) The high negative correlation between high temperatures and negative "energy out-in" is obvious.

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Soil Temperature

The soil-temperature-data-logger battery had too low a voltage for the last two days of February.

Plants pictures

Comparison of the four quadrants:

Roper plot:

  • West row on right: Dark Green Bloomsdale Spinach (Wyatt-Quarles Seed Co.) Rows 12” apart, plants thinned to 5-6” apart, maturity 45-70 days (24 December 2010-19 January 2011)
  • Center row: Champion Collards (Wyatt-Quarles Seed Co.) Rows 24-30” apart, plants thinned to 12-18” apart, maturity 60-75 days (9-24 January 2011)
  • East row on left: Great Lakes Lettuce 118 (Burpee USDA organic) Rows 12’ apart, plants thinned to 8” apart when 1-2” high, maturity 45 days (24 December 2010)

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L. David Roper,;