As a firm headquartered in the Kansas City area with offices across the US, including the northeast, big temperature swings are something we’re used to here. This week, as we face an arctic blast brought on by the polar vortex, many of our clients are facing the prospect of single digit (and below) temperatures. This is what we call a “design day,” which presents the maximum conditions that an HVAC system is typically designed to handle while maintaining the desired space temperature. The high in the Kansas City area on Friday is predicted to be around 5°F, which corresponds with the 99.6% heating design temperature guidance from ASHRAE.
In preparation for these frigid temperatures, there are a few things building owners and operators can do to help maintain control of their systems and keep their buildings warm during these cold snaps.
- Temporarily remove overnight temperature setbacks. This will help prevent the building from getting too cold overnight and taxing the system to reheat the space in time for the next day of occupancy. Remember to reinstate these setbacks once the cold snap is over though, to take advantage of the energy savings that come from them.
- Extend the warm-up period on your air handling equipment by adjusting the optimal start time. By scheduling the warm-up period to start earlier, your system has more time to pre-heat the building to the occupied temperature setpoint.
- During unoccupied hours, run the air handling equipment in recirculation mode. Recirculation mode will keep the outside air damper closed to maximize the heating effectiveness of the air handling equipment. During occupied hours the outside air damper should remain open though, to meet code requirements and help prevent the spread of viruses.
- Increase the temperature of supply air coming from the air handing equipment. This will maximize the available capacity in the heating coil. However, be careful not to set it too high, otherwise you’ll end up with the stratification of hot air in the space.
- Check your filters. A dirty filter will reduce the overall amount of warm air the equipment can deliver to spaces.
In some high-rise buildings, street-level tenants may find it nearly impossible to keep their space warm despite following these recommendations. In these cases the difficulty may be a result of stack effect, which causes cold air to be pulled into a space because of a pressure imbalance due to improperly isolating the tenant space from the main building.
To learn more about how keep your mechanical system in check during extreme conditions, contact our director of engineering, Jared Carlson, today.