Office buildings

The primary areas of focus for energy retrofits in office buildings are: optimizing HVAC systems (including air distribution, heating, and cooling), upgrading lighting systems, reducing supplemental power loads (such as office equipment), improving the building envelope (windows, insulation), and implementing operational and maintenance (O&M) best practices. This involves strategies like existing building commissioning (EBCx), using variable speed drives (VFDs) for pumps and fans, using occupancy sensors for lighting, and adding or improving building insulation. These areas are generally addressed through either standard retrofits or more extensive “deep” retrofits that address multiple systems holistically.

Lighting upgrades include replacing older, less efficient lighting technologies (such as incandescent or older fluorescent lights) with high-efficiency LEDs. Strategies such as delamping (removing unnecessary lamps), installing occupancy sensors to control lighting, taking advantage of natural daylight through light shelves and building orientation, and utilizing specular reflectors to maximize light output can significantly reduce lighting power density (LPD). It is also important to ensure lighting levels are tuned to specific tasks and spaces, avoiding over-illumination. Utilizing addressable ballasts for lighting control can also contribute to improved efficiency. Exterior lighting should also be addressed for increased efficiency, and exit signs should be updated to LED versions.

HVAC improvements can be made by implementing various strategies. These include: optimizing the control of air handling equipment (e.g., economizer controls, supply air temperature reset), improving duct system efficiency (by reducing leakage), implementing demand controlled ventilation (DCV), ensuring proper valve operation and calibration, adding variable frequency drives (VFDs) to pumps and fans, and adding or improving economizers. For heating and cooling, strategies include replacing older, less efficient boilers and chillers with modern, high-efficiency models; using modulating boilers for more precise heating control, and implementing condenser water reset and optimizing cooling tower operation. Improving the chilled water pumping system to a variable primary system, and adding a waterside economizer are further ways to increase efficiency. Heat recovery from exhaust streams, solar air heating, and variable refrigerant flow (VRF) systems can also be considered.

The building envelope, including windows, walls, and roofs, significantly impacts a building’s energy performance through heat gain and loss. Improvements include: minimizing air infiltration with air barriers, adding insulation to walls and roofs to meet or exceed requirements, and upgrading windows and doors with energy-efficient models, which have low U-values, low-e coatings, and controlled Solar Heat Gain Coefficient (SHGC). It is also important to address the type of glazing and frames used, as well as any thermal bridging from IGU spacers. Cool roofs can also reduce solar heat gain.

When selecting replacement windows, prioritize those with a low U-factor (for better insulation), low emissivity (low-e) coatings (to minimize radiative heat transfer), and a suitable Solar Heat Gain Coefficient (SHGC) based on building orientation. Consider also maximizing visible light transmittance (TVIS) to increase daylighting and reduce reliance on electric lights. The whole window assembly's U-factor (including glazing, frame, and spacers) should be used for comparison, rather than the center-of-glass U-factor. Warm edge spacers should be used to minimize thermal bridging.

To reduce power loads from office equipment, building owners and operators should encourage the use of ENERGY STAR-certified equipment, implement policies to ensure that equipment is turned off when not in use, and consider policies for the use of personal powered devices. Implementing an employee energy awareness program can also contribute to reducing plug loads. Retrofitting data centers and using energy-efficient transformers are additional steps that reduce overall consumption. Vending machine controls, such as VendingMiser, CoolMiser, and SnackMiser, can also limit energy waste from machines.

EBCx is a systematic process for improving the energy performance of existing buildings by identifying and correcting operational and system deficiencies. It involves verifying that building systems are operating according to design and within their proper parameters, calibrating sensors, and optimizing control strategies. EBCx is important because it helps to identify and address issues like leaky dampers, faulty valves, or inefficient control sequences. It is typically a less expensive means of increasing overall efficiency of a building than replacing entire systems.

Measurement and verification (M&V) is the process of quantifying the actual energy savings achieved from energy retrofit projects. It involves developing a plan, selecting an appropriate M&V approach, characterizing the measures being implemented, and verifying the savings through data analysis and reporting. M&V is essential to demonstrate that energy efficiency investments are effective and to assure ongoing performance of systems. This process ensures that the retrofit achieves its intended results, allowing ongoing performance to be assured and to make adjustments where needed. Building performance tracking is a key element of M&V, and it often includes the use of a program like Portfolio Manager to track energy use metrics, like EUI and ENERGY STAR scores.