Heating and Cooling Systems
Heating, Ventilation and Air Conditioning (HVAC) account for 51 percent of energy use in buildings. A smart, integrated HVAC system can improve air quality, create a more comfortable work space and save energy and cost. You should always consult with a contractor in determining your facility needs and the best solution for you. Some of the types of HVAC technology include:
- Dedicated outdoor air systems improve humidity control.
- Electronic expansion valves (EXV) enable systems diagnostics and save up to 15 percent on energy costs.
- Desiccant dehumidification absorbs moisture and transforms it into heat.
- Micro channel heat exchangers offers improved heat transfer and thermal performance.
- Chilled beam cooling produce cool air directly in building to reduce energy use.
- Adjustable speed drives (ASD) reduce motor speed for varying HVAC loads.
- Variable refrigerant flow (VRF) systems transport refrigerants in place of air or water and are flexible in capacity and design.
- Displacement ventilation utilizes a low-velocity stream of fresh, cool air on the ground to displace stale, warm air near the ceiling.
- Energy recovery ventilation uses captured energy from exhaust air to precondition incoming makeup air.
- Economizers can help HVAC systems work more efficiently, utilizing outside air when temperatures are cool, reducing air conditioning costs. Dry bulb HVAC economizers are less costly, but only sense air temperature. Wet bulb HVAC economizers block humid air, generally making indoor temperatures more comfortable. You should consider climate, hours of operations and other factors when installing air conditioner economizers.
It's important to continuously monitor and keep records of your air quality in order to keep improving your conditions. For further details on best practices for HVAC maintenance, please refer to this checklist from the US CDC.
Learn more about air quality and ventilation solutions
There are a number of specific areas where you can find opportunities to save energy and lower costs:
You can reduce energy usage based on building's schedules, by using controls that coordinate with occupancy schedules and nighttime temperature setbacks. You should also be using temperature and time controls, which include standard programmable thermostats or digital controls.
You can also use proper humidity to control to maintain a comfortable environment while still raising your indoor temperature. Studies show that summer operation at 78 degrees and 30 percent relative humidity provides the same level of comfort as does 74 degrees and 70 percent relative humidity.
Air conditioning makes up 15 percent of energy use in commercial facilities, so it's important to keep them maintained and in good working order. Clean and inspect the system regularly, including checking air filters monthly and cleaning or changing them when necessary. Monitor the refrigerant charge levels and adjust if necessary.
You can also prepare your air conditioning system for warmer weather, which can help prevent future damage and reduce operating cost.
- Inspect refrigerant circuits and controls, compressor, air cooled condensers, evaporative condenser, cooling towers, chillers, and absorption equipment.
- Check and repair damages, gauges, and levels.
- Calibrate controls and lubricate moving parts.
Green Building Systems and Equipment Checklist
When you have the chance, always make sure your boiler systems are updated to newer, more efficient models. Replacing a system greater than 15 years old saves an average of 20 percent on fuel costs, 32 percent for the installation of a condenser boiler, and 40 percent if proper heating controls are also installed.
Upgrading improves fuel combustion and reduces nitrogen oxide emissions, and also results in greater efficiency. Consider converting from a single-boiler system to a staged system.
Before replacing anything, it's important to understand your existing system's efficiency and calculate the energy savings of a new system. Make sure to consult building engineers and maintenance specialists to coordinate the building's heating load with the heating system's capacity, ensuring that you select the appropriate system for your needs.
Before replacing your boiler with a more efficient model, consider:
- Are your building heating load and boiler sized accordingly?
- Do you have a right-size boiler with energy-efficient systems?
A boiler economizer captures waste heat from exhaust flue gasses and preheats the boiler feedwater. Boiler economizers increase efficiency by 2-3 percent. The best boiler systems to utilize boiler economizers exceed 100 hp and operate at pressures of more than 75 psig. New burners improve combustion and reduce nitrogen oxide emissions. Baffle inserts increase the efficiency of heat transfer. Use new burners to maintain the proper air-to fuel mixture, and baffle inserts to force combustion.
Follow appropriate boiler operations and maintenance practices
Following O&M guidelines reduces energy consumption and lowers energy costs. There are a number of steps that this includes:
- Monitor flue gas levels and temperature using flue analyzers and oxygen trim system
- Use shutdown and idle option when appropriate
- Remove scale buildup from boiler tubes regularly
- Inspect boiler insulation regularly, check for steam trap leaks and repair any damage.
Maintain air-fuel ratio in boilers for gas- and oil-fired systems
Optimizing air-fuel ratios is a simple solution to maximize efficiency and combustion, minimize heat loss, and reduce costs. Inadequate air within boilers results in combustibles like fuel, soot, smoke, and carbon monoxide. Too much air results in heat loss and inefficiency due to increased gas flow within the flue.
To measure the amount of excess air, use a gas-absorbing test kit. Also consider a computer-based analyzer to measure oxygen, stack-gas temperature, and boiler efficiency if your system has annual costs greater than $50,000.
Use radiant heat where possible
Radiant heat systems use radiant panels, hydronic floor heating, and infrared heating, which directly transfer heat to objects instead of the air. Hydronic heating pumps hot water through pipes laid under the floor and can save up to 50 percent on energy costs. Infrared heating directly transfers heat through electromagnetic waves of invisible light. Infrared heating saves approximately 30-70 percent in fuel costs.
Radiant heat systems are quieter and quickly heats spaces without high maintenance costs. There is a space requirement, so make sure your facilities are suitable.
- Use Pressure and temperature reset controls, which minimize fuel waste by matching supply and demand for heat. Temperature pressures resets increase energy efficiency and reduce fuel waste.
- Use heat exchangers to pre-heat the makeup water and cool down the blow-down water before discharge. Blow-down heat exchangers are most beneficial on larger boilers.
- Install a condensate return system if appropriate. Condensate return systems reduce fuel usage, make-up water, disposal costs and chemical treatment costs.
- Monitor furnaces for carbon monixide emissions by using CO detectors. Carbon dioxide levels should not be above 220ppm. Low carbon monoxide levels save fuel by reducing energy usage.
- Monitor water quality in radiant heating systems. This allows you to eliminate fouling of the hydronic system, reducing system costs.