Heating & cooling
Save money, energy with efficient HVAC equipment
Efficient use of heating, ventilation, and air conditioning (HVAC) equipment not only saves energy and money, but also can extend the life of your equipment. Here are some tips:
- Optimize heating and cooling systems
- Adjust controls to energy-efficient, comfortable levels
- Minimize heat loss
- Shut down equipment when not needed
- Only heat and cool spaces where necessary
- Keep all HVAC components clean
- Inspect all HVAC components and fix if necessary
- Consider an energy management system (EMS)
During winter (heating season) heat your building to a maximum of 21°C (70°F) when occupied, 16°C (61°F) when unoccupied. Heating and cooling set points must be set 2-3°C (3-5°F) apart so that the air conditioner does not cycle (turn on and off) frequently.
- Start the morning temperature pick-up with outside air dampers closed so that the building is at 18°C (65°F) when occupants arrive.
- Complete the warm-up during the first hour of occupancy. Similarly, set back the temperature for the last hour of occupancy.
- During summer (cooling season) cool your building to no lower than 24°C (75°F) when occupied. Avoid mechanical cooling when it is unoccupied, unless necessary for morning pre-cooling.
- Start morning pre-cooling so that the building is 26°C (78°F) when occupants arrive at the first hour of occupancy.
- Keep the outdoor air damper closed during the morning warm-up in winter and fully open during the summer cooling season.
- Where applicable, install adjustable speed drives on fans, chiller water pumps and heating pumps.
- Maximize the use of outdoor air for space cooling using existing system capabilities and during the summer cooling season, flush the building during the night with cooler outdoor air.
- Consider converting constant air volume systems to variable air volume systems.
- Consider converting dual duct systems to single duct systems.
- Electronic programmable thermostats automatically adjust your building's temperature at night and on weekends. They are very reliable and easy to install.
- For larger or more complex buildings, consider using a building automation system, also known as an energy management system, which will efficiently manage all the energy usage for the building. These systems can save 5-30% in energy costs and have a payback of two to four years depending on the hours of operation used, type of system and equipment controlled.
- Ensure that your water-heating equipment is capable of heating to at least 45°C (113°F) and not above 60°C (140°F). Shut down domestic hot water circulating pumps with a time switch during unoccupied hours.
- Water heating temperature controls can increase comfort in your building, while reducing energy costs. The controls vary the temperature of supply water as a direct response to the outdoor temperature.
- Calibrate all thermostats and gauges, adjust controllers and dampers for tight closure and test all controllers for proper operation. Lock your thermostat or instruct employees not to tamper with the settings.
- Office areas in buildings with high-ceilings (like warehouses) need their own ceilings, not just wall partitions. Otherwise, warm air rises to the high ceiling, causing the heater to run constantly. If your building's ceiling is higher than 3.0 meters (10 feet), consider installing ceiling fans to force the warm air down to the occupied level. As the temperature gradient will be minimal, the heat loss will be reduced.
- In loading areas, install a relay switch on your heating system so that the heat goes off when doors are opened. If loading areas are in heavy use, consider partitions and local heaters for staff.
- Bare pipes and ducts running through unconditioned space should be insulated to curb heat loss/gain and deliver heating and cooling to the target space.
- Use pumps, fans and electrical water heaters at optimal times only.
- Shut down non-critical equipment during peak demand period.
- Shut down heating pumps when the outdoor temperature is above 18°C and if no reheat is required. During cooling, turn off re-heating (if practical).
- Shut down chiller, chilled water pumps, condenser water pumps and cooling tower fans at the earliest time possible in the evenings and on weekends. This may require a small stand-alone system for computer equipment rooms.
- Reduce heating and cooling spaces used only for short periods. If possible reduce temperature or shut off heating in vestibules, stairwells, lobbies and unused spaces.
- To reduce cooling energy, shut off all unnecessary light, cooking equipment and office equipment.
- When the building is unoccupied, turn off exhaust fans in washrooms and kitchens with a timer. Also shut off outdoor air dampers and the supply air fan one hour prior to the end of occupancy.
- To maintain unrestricted airflow, keep condenser coil face clear of all debris.
- Keep the cooling tower clean to minimize both air and water pressure drops. Clean intake strainer and inspect spray nozzles for proper performance.
- Clean air inlet screen, spray nozzle and pump screen to ensure they are not clogged.
- Regularly clean water side chiller and boiler tubes.
- Clean refrigerant and water coils with a high-pressure mixture of water and detergent to allow for maximum heat transfer.
- Check reflectors in electric radiant heaters for proper beam direction and cleanliness.
- Inspect all ductwork (including flexible connections) for air leaks. Seal leaks by taping, caulking or replacing flexible connections.
- Insulate all bare ducts and pipes that carry conditioned air and chilled or hot water.
- Inspect all dampers, blades, edge seals and linkages. Replace and adjust if necessary.
- Inspect inlet vane damper linkage for smooth operation and control of airflow.
- To ensure proper seating for minimal leakage, inspect air valves in dual duct mixing boxes.
- Repair any leaks from pipes, taps, pumps and control valves.
- Replace air filters at regular intervals or at pre-determined pressure drops.
- To prevent overheating and overcooling, adjust all variable air volume boxes so they operate precisely.
- Where applicable, install ASDs on fans, chilled water pumps and heating pumps.
Consider installing an energy management system (EMS) to control all facets of your building's operation and identify maintenance issues. An EMS is a centralized control system that takes over manually controlled functions. It can be a simple unit connected to one or two pieces of equipment or it can be more complex and control lights and equipment throughout your facility.
Some of the key benefits of an EMS are:
- Can monitor total building loads and turn on or off appropriate equipment
- Can analyze outside and inside temperatures and regulate the HVAC system in your building
- Can save 5-30% in energy costs and can reduce your demand charges
- Have a payback of two to four years depending on the hours of operation used, type of system and equipment controlled
Take advantage of HVAC controls
Automated controls for HVAC systems (heating, ventilation, air conditioning) can provide energy savings and comfort in all kinds of facilities. While large office buildings often make use of HVAC controls, small businesses sometime overlook the value that controls can offer.
How you can take advantage of HVAC controls:
- Segment buildings that use some sort of central HVAC equipment into temperature-control zones. This allows occupants to cut back on space conditioning in rooms temporarily unoccupied, without sacrificing comfort in the rest of the building. Each zone should have its own programmable thermostat, which can be programmed to communicate via a network.
- The building's central HVAC equipment needs controls that can communicate with the thermostats. While the controls on the HVAC unit execute most of these strategies, the thermostats are the true "brains" of the system. It is important that these thermostats are programmed carefully to function well, and communicate well with the HVAC unit controls. Ideally, the HVAC unit will be equipped with a variable-speed drive so output can be matched to demand at the source.
Control strategies that often work well in small buildings include:
- Optimal start/stop. Programs desired times for the systems to automatically turn on and off.
- Demand limiting. Turns off the HVAC systems when energy demand reaches a pre-set threshold.
- Smart staging. Activates the compressors in air conditioning units as cooling demand increases over the course of the day.
- Free cooling. Makes use of outdoor air when ambient temperature is 15°C or lower.
- Night purge. Flushes out the building with cool outdoor air prior to occupancy in the morning. Owners sometimes are not aware of control opportunities already available to them through their existing equipment. Take the time to learn about what your thermostat and HVAC system can do.