So in my last blog I asked the question how much does it cost to heat or cool a school building using Geothermal Energy? I have been gathering electrical energy usage data for all systems involved in the Harriet Beecher Stowe School HVAC system. If you click the link Data it will take you to a Google Docs spreadsheet that details days of readings in 6 minute intervals. This data is a combination of automation trending software and HOBO Data logging software.
Don’t click yet! Click too soon and you will be doing some serious scrolling. Along the far left there are small up and down arrows that will expand the data and show the entire day. Along the top row you will find a description of the underlying content. Columns N and O are for BTUh data and you will notice that some of this is represented by a negative value. Most of this happens during unoccupied building status and the BTUs actually exchange in reverse. Please note that anything reflected by a negative is formulated as a zero.
Column R is the KWh usage for that 6 minute snapshot.
Column S is the KWh value x $.13 and that is the average KWh cost for the month including demand and KVAR.
Columns T, U, V, W are the daily summaries.
1st line = Total KWh for the day
2nd line = Total C.M.P. cost for the day
3rd line = The amount of BTUs extracted from the geothermal field for that day
4th line = Cost to condition the building per square foot.
5th line = Average outside air temperature for that day
As you scroll down and observe the day to day totals, you can easily see the benefit of automation. By using the night time set back in a building you can save approximately 50% of your energy costs for 2 days a week. That savings also reflects the savings during the night set back during the week. The systems in this building start ramping up at 5:10AM and shut down at 4:00PM. On school snow storm cancellations or non-school session days we will set the systems to administration areas only because we will have limited occupancy. That reflects the value of training key building people to manage their systems with automation.
HVAC systems included in this data
H=Heating, water to air heat pumps, unit air handlers and ceiling mounted radiant panels
V=Ventilation, ERV, (energy recovery ventilation) operation of CO2 demand ventilation in all spaces
AC=Air Conditioning in all school and administrative function spaces.