Utilities can use Customer Data to Help Business Customers Improve Energy Inefficiencies
By Andrew Klein, FirstFuel Software
It’s the heart of heating season and many smaller buildings have switched off their cooling equipment until the warm weather returns. For larger buildings with high internal loads from computers and people, however, cooling systems often continue to operate right alongside heating systems. The need for both heating and cooling is even more prevalent in the fall and spring when temperatures can range from 45 F to 75 F. When managed improperly, inefficient energy use can occur.
Simultaneous heating and cooling (SHC) occurs when heating and cooling systems battle it out to condition the same space at the same time. Sometimes SHC is used on purpose for humidity control–for example, to defog car windows. More often, however, SHC happens unintentionally and wastefully. In these cases, it’s like driving your car with the accelerator fully depressed while using the brake to control your speed. Unnecessary SHC can persist because resulting space temperatures are often comfortable, therefore, tenants don’t notice or complain to building management staff. This allows SHC to fly under the radar.
What businesses might not know is that their utility can be a trusted partner that understands their energy use and might be able to provide invaluable cost-saving advice. As the energy industry evolves and utilities devise ways to offer more than just monthly bills to their business customers, utilities are increasingly lending their expertise to help improve energy inefficiencies like SHC. By leveraging streams of historic customer data, utilities can provide customized recommendations based on the specific needs and known preferences of each customer.
Utilities can provide businesses with insights that indicate if and when there is an efficiency issue. In the case of heating and cooling, utilities can do this by analyzing:
“- Previous monthly energy usage. For example, SHC might be an issue if building occupancy has been the same all year and energy consumption is higher in the spring and fall.
“- Heating and cooling operations. By offering incentives for a building “check-up,” including a manual inspection of heating and cooling operations, utilities can determine if systems are operating at the same time in the same building zones.
“- HVAC system performance. Utilities should analyze usage data and perform a physical evaluation for more complex HVAC systems to ensure everything is up to snuff, and identify any needs for repairs or replacement.
An office building in Connecticut that has electric heat and air conditioning is a good example. The building’s electric consumption would be expected to be lowest in the relatively mild days of the shoulder seasons, when both heating and cooling needs are minimal. Instead, Figure 1 shows that during most of the shoulder season days (the blue line), energy consumption is higher than in summer or winter days.
Assuming the building occupancy was the same all year, it’s possible that SHC drove this high shoulder season consumption. A utility, therefore, could recommend investigating to determine whether this was an issue for this building. When unnecessary SHC is suspected, utilities might recommend several measures to help mitigate the problem:
“- Adjust heating system settings. The customer could disable heating systems that serve the perimeter areas anytime the outdoor temperature is above 60 F during occupied days, and 50 F at night. This will help reduce the instances of heating and cooling systems operating at the same time.
figure 1 : Seasonal Electricity Consumption with Evidence of SHC
“- Look for portable space heater use. The customer could check whether tenants are using portable electric space heaters, particularly in areas that are overcooled by central systems.
“- Evaluate equipment operating schedules. The utility can help the customer assess operating schedules for existing building zones. This is the first step in eliminating running the HVAC when floors or areas are unoccupied. In addition, by implementing an overtime occupancy system, ventilation can be provided in areas that need to be occupied on an occasional basis.
“- Correct thermostat settings. The customer should ensure heating and cooling setpoints are spread by at least 4 F, and check that the night setback is operational. If thermostats that control perimeter heat are independent of those controlling central air handling units, they should have setpoints that are several degrees lower than that of the air handling unit thermostat.
“- Link air handler discharge temperature to outdoor air temperature. Instead of resetting air handler discharge temperature based on return air temperature, the control air handler discharge temperature should be based on outdoor air temperature. Controlling discharge temperature based on return air can drive the discharge temperature lower when there is excessive space heating.
For comparison, Figure 2 shows seasonal days for an electrically-heated office building in Maryland. The shoulder season (again shown in blue) exhibits a morning double peak pattern similar to the winter (shown in green). There is, however, less reason to suspect unnecessary SHC because shoulder electric consumption never exceeds that of the other seasons.
figure 2 : Seasonal Electricity Consumption with no Evidence of Simultaneous Heating and Cooling
Although there is no evidence that the Maryland building is operating with unnecessary SHC, the graph provides additional insights into the building’s winter performance. During late evening and early morning (6 p.m. to 6 a.m.), the winter consumption is higher than the shoulder and summer–an indication that electric heat is operating during the unoccupied parts of the day. Furthermore, the winter consumption, which is likely associated with heating, begins to increase at about 3 a.m. This is earlier than necessary for most buildings, and particularly for buildings that experience Mid-Atlantic winters.
This building’s energy consumption can be lowered by making changes to the building management system. If the heating system is over-operating at night, the following measures are recommended:
“- Choose the right nighttime temperature. Proper night setback should be implemented across all zones of the building. An unoccupied heating setpoint of 55 F is recommended.
“- Look for other unoccupied setbacks. If heat is operating at night, it might also be operating during the daytime on weekends and holidays. Make sure unoccupied setpoints apply to all unoccupied periods of the year.
“- Check zone thermostats. Often, operators find that many building areas have had their independent zone thermostats changed, causing spaces to overheat.
“- Tighten HVAC equipment schedules. The existing building schedules should be modified to properly mimic the occupancy schedule of the building. For office buildings, HVAC equipment should start between 6 a.m. and 7 a.m. and shut-down between 5 p.m. and 6 p.m. The heat can be turned down and the building can “coast” the last hour of the day.
Another tool for measuring building performance is the weather response chart. The building’s electric meter data and local weather data can be fed into an analytical weather model that isolates the weather-related energy use each hour of the year. The average weather-related electric demand (kW) is plotted for each corresponding outdoor air temperature. Figure 3 illustrates the weather response for the Maryland building.
figure 3 : Weather Response Chart
The first thing that can be confirmed from the weather response is the heating and cooling type. Because the weather-related consumption increases as weather goes from mild to hot, the building is air conditioned, and because the weather-related consumption increases as weather changes from mild to cold, the building is heated with electricity.
Further, the occupied weather response (red) is plotted separately from the unoccupied weather response (blue), illustrating the effectiveness of nighttime HVAC setback. Ideally, if the building completely shuts down at night, the blue line would be flat, meaning there is no change in consumption due to weather at night. It is clear from Figure 3 that the building is not setting back HVAC equipment at night.
By providing these types of proactive and personalized recommendations, curated and prioritized above the hundreds of other possible opportunities in a building, utilities develop deeper relationships with customers. Through valuable interactions, utilities can spur a positive dialogue about the appropriate energy services for their business customers. In addition, with software-based analytics, utilities can perform the analysis and make many of the needed recommendations to thousands of their customers instantly, no longer constrained by account managers’ time or areas of expertise. Utilities that take steps to proactively engage with business customers in this way will secure their spot in the value chain of the ever-evolving energy landscape.
Andrew Klein is a building energy engineer at FirstFuel Software, a SaaS company that provides a business customer engagement platform for utilities. Through the analysis of building energy use, Andrew arms utilities with recommendations on energy efficiency measures for their business customers. Andrew is also a Registered Professional Engineer in Massachusetts and holds a Certified Energy Manager credential.