Managing Building Energy Consumption
Retro-Commissioning, Measurement & Verification, and Ongoing Performance Management
It’s open season with no bag limit all year ‘round in Florida for hunting feral hogs—and no hunting license is required! The same could be said in buildings here—killing your building energy hogs should be an ongoing effort—and there’s no limit.
At a workshop organized by the U.S. Green Building Council North Florida chapter, David Miller, an experienced Energy Performance Consultant with TLC Engineering for Architecture, recently told us about the fast cash paybacks available from making sure your building is running properly and you’re using the latest cost-effective equipment.
Commissioning (or retro-commissioning or re-commissioning) is a methodical process for getting the most from the energy budget for your building and use of it—and for saving money by avoiding unnecessary expense for energy use. This applies for commercial and residential buildings. During commissioning, a building’s design and equipment is tested, settings are tuned, problems are solved, and the superintendents/residents are trained in operations of the building. It’s a very cost-effective quality assurance process.
Building Energy Fundamentals
Buildings use about 41% of our nation’s energy; about 74% of our electricity. Ranking next in energy use are transportation, and then industry.
The biggest use of energy by buildings is for Heating, Ventilating and Air Conditioning (HVAC)—and one of the biggest opportunities for energy savings. The percentages vary a bit by local climate and by type of building use, but HVAC and water heating combined account for 55%-59% of building energy consumption. The shares of this use shift widely in Florida from north to south, among heating, cooling and water heating; and energy use for ventilation is an important factor in commercial buildings. Next on the building energy savings opportunity list are lighting and refrigeration. See details about energy use in residential buildings on the Florida Solar Energy Center website.
Business use varies widely by activity, and home energy use differs from commercial use in general. BUT in the end, our use of energy in buildings is substantial. A building’s energy footprint is bigger than one might imagine. It’s hard to bag feral hogs—they’re wily and most-often out of sight—yet they are very active and impactful across the landscape. Consider the whole lifecycle of energy (and its climate impacts), including: mineral fuel extraction, pollution emissions (refrigerants, CO2), building energy use intensity (EUI), and the efficiency of the structure’s components and equipment. And we pay for this in our electricity and other fuel bills—and other ways externally.
Commissioning is not hard to do and not expensive—payback from the basics is usually in 1-2 years. It takes some training, tools, interest and continuing attention to adjustments to realize the benefits—cash and other benefits that accrue in time. The approach outlined by Mr. Miller is simple:
3-steps approach to efficiency via commissioning
- Make sure it’s Off when it’s supposed to be Off.
Among the most beneficial areas of opportunity are Lighting, Building Automation, Variable Air Volume (VAV) Retrofit, and Replace Roof-top HVAC units
- Make sure it’s working right when it’s On.
Needs vary by type of business and activity. Especially in Florida, humidity control: limit outside air ventilation when occupancy is low, to allow the building to dry out overnight.
- Is there a better way?
There are several typical areas of improvement cost-effectively available to building owners: Replace old-fashioned lighting; Replace old HVAC; Improve the building envelope (seal cracks, replace old windows, insulate roofs/ceilings, replace old doors); Improve control systems; use high-efficiency motors & variable-speed drives; change to low-flow water fixtures.
Opportunity for savings from commissioning was evaluated by a Lawrence Berkeley National Laboratory study of 643 buildings over 10 years. With building commissioning, median energy savings of 16% were obtained from existing buildings, 13% from new buildings; typically payback of costs was in only 1.1–4.2 years. Click here for an overview of the business case.
The federal Better Buildings Challenge asks leading organizations to commit to reducing the energy use of their buildings by at least 20 percent over 10 years.
Commissioning is a process, not an event — and it depends on measurement (data, evaluation, action; data, . . .)
With today’s data technologies, one should be able to know how a building was operating in the last hour. BUT, there’s need for a person who’s curious to use the data collected. Commissioning should be a multiple-stage process, with feedback loops and follow-ups. Don’t just fill out forms and collect data—think about the information, do something to change the building and its operation; track more data and review. Iterative, small changes will add up to big savings. Sub-metering is now cost effective: data logger devices now cost just $80-100; big ole’ installed meters $1000-$1500. Use some building energy tracking software (now modest cost, too) and really control your building (on a PC or one’s smartphone).
There are professionals that can help—first, talk with your local electric utility. A typical Energy Audit may cost 10¢ to 20¢ per sq. ft. (for homeowners in Florida it’s free). Undertaking a more thorough retro-commissioning process may cost a bit more, but it should be the first Energy Conservation Measure undertaken: commonly you’ll get a 1.1-2 year payback. It’ll be most cost effective at institutions with larger electric bills (e.g. $10,000 or so per month).
Major areas of opportunity
Mr. Miller identified a few energy conservation measures that are typical big areas ripe for improvement. HVAC is the typically biggest end-use, yet there are many other measures that are easier to commission, including:
- Lighting – 2-4 year payback; 35%-50% reduction in Watts. Typically installed are modern fluorescent bulbs or now more and more, LEDs.
- Demand Control Ventilation – schedule HVAC use in coordination with building use. Use programmable thermostats on up to whole-building computer-controlled systems.
- Static Pressure Reset (manage air pressure and flows to keep conditioned air where it is needed).
The commercial building energy efficiency standards now or being adopted in most states, ASHRAE 90.1 2012, adds plug loads (end-user equipment: TVs, copiers, toasters, etc.). Now we’re getting into guiding the behavior of building users; we’re seeing more technology available for controls. Building codes are needed to help keep us moving forward together: users, owners, builders and manufacturers.
Your building (where you work or where you sleep) is probably thundering with wild energy hogs, and it’s open season for the hunt. It takes getting out there with tools and being involved to hunt down and kill the energy hogs. Call together a hunting party today and bring home the bacon.