The rooftop unit (RTU) decision tree can be used for preliminary screening for replacement of RTU units with more efficient units. This decision tree organizes RTUs into bins for “retrofit,” “replacement,” “no action,” or “needs further analysis.”
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Older, inefficient commercial rooftop unit (RTU) air conditioning systems are common and can waste from $1,000 to $3,700 per unit annually, depending on the building size and type. By replacing or retrofitting them, you can save money, improve your energy efficiency, make your building more comfortable, and help the environment. The Advanced RTU Campaign (ARC) encourages commercial building owners and operators to replace their old RTUs with more efficient units or to retrofit their RTUs with advanced controls in order to take advantage of these benefits. This website shows updates to the campaign including resources and progress towards the campaign's goal.
Plug and process loads in commercial buildings account for 5% of U.S. primary energy consumption. Minimizing these loads is a primary challenge in the design and operation of an energy-efficient building.
Plug and process loads (PPLs) in commercial buildings account for almost 5% of U.S. primary energy consumption. Minimizing these loads is a primary challenge in the design and operation of an energy-efficient building. PPLs are not related to general lighting, heating, ventilation, cooling, and water heating, and typically do not provide comfort to the occupants. They use an increasingly large fraction of the building energy use pie because the number and variety of electrical devices have increased along with building system efficiency. Reducing PPLs is difficult because energy efficiency opportunities and the equipment needed to address PPL energy use in office spaces are poorly understood.
Case study describing how adidas implemented a best practice of a planned replacement program for its rooftop units (RTUs), which resulted in significant cost and energy savings. The case study outlines the planning process, implementation, results, and the future plans of their RTU replacement program.
This case study details the very successful Walgreens proactive RTU replacement program that has resulted in 50% efficiency improvements. The streamlined process allows Walgreens to reduce installed cooling capacity, increase RTU efficiency, provide improved service, and reduce overall costs compared to emergency replacements.
This guide presents a set of 15 best practices for owners, designers, and construction teams to reach high-performance goals and maintain a competitive budget. They are based on the recent experiences of the Research Support Facility owner and design-build team, and show that achieving this outcome requires that all key integrated team members understand their opportunities to control capital costs.
This presentation discusses the importance of selecting a project delivery method that balances performance, best value, and cost savings.
Presentation by NREL researcher Shanti Pless about Controlling Capital Costs in High-Performance Buildings Using a Performance Based Design-Build Process
Low energy or high-performance buildings form a vital component in the sustainable future of building design and construction. Rigorous integrated daylighting design and simulation will be critical to their success as energy efficiency becomes a requirement, because electric lighting usually represents a large fraction of the energy consumed. We present the process and tools used to design the lighting systems in the newest building at the National Renewable Energy Laboratory (NREL), the Research Support Facility (RSF). Daylighting had to be integrated with the electric lighting, as low energy use (50% below ASHRAE 90.1-2004) and the LEED daylight credit were contractually required, with a reach goal of being a net-zero energy building (NZEB). The oft-ignored disconnect between lighting simulation and whole-building energy use simulation had to be addressed, as ultimately all simulation efforts had to translate to energy use intensity predictions, design responses, and preconstruction substantiation of the design. We present preliminary data from the postoccupancy monitoring efforts with an eye toward the current efficacy of energy and lighting simulation methodologies.