Longer-term solutions should also be considered, especially for building owners who occupy their buildings. Although the actions covered in this section require more-extensive implementation and have higher costs, they can dramatically increase the efficiency of your facility and can often improve the working environment as well. Ask your local utility representative for more information about incentives for such projects. If you rent or lease your building and pay your own utility bills, discuss these potential efficiency measures with the building owner.
LED lighting. LEDs offer several advantages over conventional light sources, including high efficiency, long life, and superior control. These characteristics, along with falling prices, have made LEDs a viable solution for a growing number of office building applications, including exit signs, task lighting, recessed downlighting, and ambient lighting.
LED troffers offer promising benefits in the right applications. Fluorescent troffers are the most common type of lighting fixture found in US commercial facilities, accounting for 50 percent of existing luminaires. The best LED troffer products outperform their fluorescent cousins, but at a first-cost premium. Replacement options include new LED troffers, LED retrofit kits, or swapping fluorescent tubes for tubular LED products.
When buying LED-based products, ask for performance data based on standard tests performed by accredited laboratories. When comparing LEDs to other options, account for cost savings in both energy and maintenance; make sure that the LED solution will provide the quantity and quality of light that you need.
Fluorescent lamps. If your facility uses T12 fluorescent lamps or commodity-grade T8 lamps, there are several retrofit options. Relamping with high-performance T8 lamps and electronic ballasts can reduce your lighting energy consumption by 35 percent or more. Adding specular reflectors, new lenses, and occupancy sensors or timers can double the savings. Payback periods of one to three years are common.
Daylighting. Daylight can improve the ambience of an office and reduce the need for electric lighting. Dimming ballasts and daylighting controls can be used to reduce the amount of electric light used when daylight is present.
Lighting controls . Using energy-efficient light sources is only one part of the process of reducing the energy used by a lighting system. A well-designed control system will provide the right amount of light where and when it’s needed and can cut lighting energy use by 5 to 60 percent, depending on the baseline conditions and the control strategies used. In addition, using lighting controls may qualify you for participation in utility demand-response programs. Advanced control systems can also help lighting maintenance by signaling lamp outages and monitoring usage and output to indicate when they fall below required levels. Lighting controls typically offer daylight monitors, personalized controls, occupancy sensors, and automatic scheduling.
Smart lighting design in parking lots. Parking lots are often overlit—an average of 1 foot-candle of light or less is usually sufficient. Reducing light levels, installing more-efficient light sources, and adding controls can lead to big savings. The most common lamps used for outdoor lighting are high-intensity discharge (HID) sources—metal halide and high-pressure sodium. Fluorescent and induction lamps are also used in parking lots, but LEDs have become the most efficient alternative as their performance has improved and prices have come down.
In addition to high efficiency levels, LEDs offer long life, which reduces maintenance costs. They also distribute light more evenly and produce less light pollution and light trespass—properties that improve aesthetics and contribute to energy savings.
The US Department of Energy Better Buildings Alliance, on its Adopt High-Efficiency Lighting for Your Parking Structure page, provides more information, including a sample specification, some case studies, and information on the Lighting Energy Efficiency in Parking Campaign. The Alliance estimates that using LEDs can cut energy use by 40 percent or more, depending on the application. Dimming and occupancy-sensing controls can also add to energy savings in parking lots.
High-efficiency HVAC units. A highly efficient packaged air-conditioning/heating unit can reduce cooling energy consumption by 10 percent or more over a standard-efficiency commercial packaged unit. Single-zone variable-speed rooftop units (RTUs) can also significantly reduce cooling energy. Select equipment that has multiple levels of capacity (look for “compressor stages”) with good part-load efficiency.
Advanced RTU controllers. Retrofitting existing RTUs with advanced controllers improves functionality and offers potential for significant energy savings. Estimates and preliminary field test results indicate energy savings of 20 percent to over 50 percent with a typical payback period of one to four years. Energy-saving features can include variable or multi-speed supply fan control, demand-controlled ventilation, and improved economizer control. Additional features can include demand response, remote monitoring, and fault detection and diagnostics.
Variable refrigerant flow (VRF) systems. VRF systems provide heating and cooling for a building by circulating refrigerant to multiple small heat exchangers instead of circulating water or moving air through ducts. In theory, VRF systems can save energy compared to other HVAC options by providing improved zone control, recovering heat for simultaneous heating and cooling, operating at partial load, and having smaller associated duct losses. Manufacturers claim savings of up to 40 percent, but we’re not aware of any independent verification.
Demand-controlled ventilation. For office spaces that have large swings in occupancy, energy can be saved by decreasing the amount of ventilation supplied by the HVAC system during low-occupancy hours. A demand-controlled ventilation (DCV) system senses the level of carbon dioxide in the return airstream, uses it as an indicator of occupancy, and decreases supply air when carbon dioxide levels are low. DCV systems are particularly applicable to variable-occupancy spaces like indoor parking garages, auditoriums, meeting rooms, and cafeterias.
Reflective building roof coating. If the roof needs recoating or painting, consider white or some other highly reflective color to minimize the amount of heat the building absorbs. Cool roofs can often reduce peak cooling demand by 10 to 15 percent. For a list of suitable reflective roof-coating products, visit the Energy Star Roof Products website.
Energy analytics software. This software offers both single-building and portfolio analysis, allowing customers to pinpoint poorly performing systems or buildings. Identifiable problems may include malfunctioning or poorly tuned HVAC systems or whole buildings that are performing at subpar levels compared to their neighbors or other buildings in a portfolio.
Commissioning is the process of ensuring that systems are designed, installed, functionally tested, and capable of being operated and maintained according to the owner’s operational needs. Doing so can cut energy bills by 10 to 15 percent or more, and often provides a simple payback period of less than one year. When this process is applied to an existing building that hasn’t been commissioned before, it’s called retrocommissioning. When it’s applied to a building that has been commissioned before, it is called recommissioning. Recommissioning is recommended every three to five years to maintain top levels of building performance. In another type of commissioning, ongoing commissioning, monitoring equipment is left in place to allow for continuing diagnostics.
Building Automation Systems
BASs, sometimes called energy management systems, save between 5 and 15 percent of overall building energy consumption and can also improve occupant comfort. Older or poorly maintained buildings can also benefit greatly from a BAS retrofit, sometimes yielding savings of over 30 percent. For existing bare-bones BAS systems, submeters and wireless controls can be added to provide more-robust information for setting baselines, benchmarking, troubleshooting, identifying areas for improvement, and evaluating performance. Recently, prices of submeters and wireless controls have dropped significantly, making them even more attractive data-acquisition tools to improve building performance.
Cloud- or Internet-Connected Thermostats
In smaller commercial buildings where even a bare-bones BAS system is too expensive, consider installing cloud thermostats, which offer BAS-like functionality at a fraction of the cost. Cloud thermostats enable programming and multistage scheduling via a wired or wireless Internet connection, have digital temperature sensors, and are able to store temperature settings and history. They also offer password protection for security, humidity control options, utility peak load management capabilities, and a wide variety of features ranging from sophisticated programmability to auxiliary inputs.