System and method for pre-cooling of buildings
A method for nighttime pre-cooling of a building comprising inputting one or more user settings, lowering the indoor temperature reading of the building during nighttime by operating an outside air ventilation system followed, if necessary, by a vapor compression cooling system. The method provides for nighttime pre-cooling of a building that maintains indoor temperatures within a comfort range based on the user input settings, calculated operational settings, and predictions of indoor and outdoor temperature trends for a future period of time such as the next day.
1. A method of pre-cooling a building, comprising:
ventilating and cooling a building with outside air if a current outside temperature is lower than a current inside temperature by a set amount, and if the current indoor air temperature is greater than a calculated ventilation cooling low limit temperature;
operating a vapor compression air conditioner, if a current time of day is between an air conditioner pre-cooling start time setting and an air conditioner pre-cooling stop time setting, and if the current indoor air temperature is greater than a calculated air conditioner pre-cooling low limit temperature that is greater than the calculated ventilation cooling low limit temperature;
measuring and storing outdoor and indoor temperatures and temperature trends; and
calculating and resetting operational settings based on user settings and indoor and outdoor temperatures and temperature trends, the calculated operational settings including at least fan speed, ventilation cooling low limit temperature and air conditioner pre-cooling low limit temperature.
2. The method as described in claim 1 , wherein the calculated operational settings further comprise a predicted minimum indoor temperature for the current day and a predicted maximum indoor temperature for the current day, and the method further comprises displaying the predicted minimum and maximum indoor temperatures for the current day.
3. The method as described in claim 2 , further comprising determining whether to change user inputs based on the displayed predicted minimum and maximum indoor temperatures for the current day.
4. The method as described in claim 1 , wherein the user settings include a minimum indoor temperature setting, a maximum indoor temperature setting, the air conditioner pre-cooling start time setting, and the air conditioner pre-cooling stop time setting.
5. The method as described in claim 1 , further including calculating and resetting the operational settings each day at a predetermined time of day.
6. The method as described in claim 1 , wherein the step of ventilating with outside air includes the steps of opening an outside air damper and operating a ventilation cooling fan at a calculated fan speed setting.
7. The method as described in claim 1 , wherein the calculated air conditioner pre-cooling low limit temperature is higher than the calculated ventilation cooling low limit temperature by an offset amount.
8. The method as described in claim 1 , further including inputting user-selected settings.
9. The method as described in claim 1 , further including selecting the air conditioner pre-cooling start time setting and the air conditioner pre-cooling stop time setting so that the air conditioning pre-cooling is enabled during a utility off-peak period and disabled during a utility on-peak period.
10. The method as described in claim 1 , further comprising operating a vapor compression air conditioner at any time if the current indoor air temperature is greater than the maximum indoor temperature setting.