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Cost-Effective Green Retrofits: Opportunities for Savings in Existing Buildings

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Start with the basics. There is an abundance of opportunities, right beneath our noses, for realizing operational savings and environmental benefits at the same time. If there is a “green lining” to the recession (as EBN explored in Jan. 2009), one piece of it may be a renewed focus on low-cost and no-cost green solutions. Experts interviewed for this article provided examples like these:

• Disabling a broken irrigation sprinkler head that had poured out 100,000 gallons (38,000 l) of water over the last two years.

By Tristan Roberts

AAdobe.jpg

Each of the three Adobe Towers is LEED-EBOM Platinum. Since 2001, a total of $2.3 million in capital costs (including $483,000 in rebates) has resulted in 47% reduced electric use, 42% reduced gas use, and 48% reduced water use, which add up to an annual savings of $1.6 million.

Photo: William Porter

Start with the basics. There is an abundance of opportunities, right beneath our noses, for realizing operational savings and environmental benefits at the same time. If there is a “green lining” to the recession (as EBN explored in Jan. 2009), one piece of it may be a renewed focus on low-cost and no-cost green solutions. Experts interviewed for this article provided examples like these:

• Disabling a broken irrigation sprinkler head that had poured out 100,000 gallons (38,000 l) of water over the last two years.

• Fixing an economizer damper that was stuck open and bringing in huge volumes of humid outdoor air during the entire cooling season.

• Installing faucet aerators and low-flow showerheads. They’re cheap and often overlooked or broken.

Basic is not always obvious. Green, cost-saving opportunities are often hidden or overlooked. Knowing where to look and what to do with what you find is the focus of this article. We’ll look at commercial buildings inside and out, from lighting to the building envelope, mechanical systems, water consumption, operations and maintenance, and other areas.

Taking a Second Look

Savings opportunities regularly materialize when building operators take a second look at any area of their buildings—from mechanical systems to lighting to water consumption. This means that commissioning, also known as retrocommissioning when applied to existing buildings, is at the top of most experts’ lists for cost-effective retrofit opportunities. Dan Ackerstein, a consultant based in Santa Cruz, California, notes, “If you hope to see any significant energy savings, the commissioning process is probably your first stop.” While any given strategy may have a lot of value in one building but marginal value in another, commissioning has value almost anywhere, says Ackerstein.

Even in buildings that have only been occupied for a short period, retrocommissioning can offer value. “As soon as buildings are occupied, designs become irrelevant,” says Ackerstein, pointing out that tenants and occupancy patterns change. Retrocommissioning involves stepping away from day-to-day concerns such as responding to complaints and performing maintenance checks. It verifies that systems operate according to the owner’s needs and intentions. It goes beyond surface-layer conditions to make sure that systems are operating at their best. “Just because people are comfortable doesn’t mean there aren’t savings opportunities,” says Mark Miller, a retrocommissioning expert with Connecticut company Strategic Building Solutions. Although retrocommissioning requires some up-front investment, typical payback is often less than two years, and 15% savings in building energy use are common.

Lighting Improvements

Lighting makes an attractive target for cost-effective retrofit opportunities. Lighting systems are relatively accessible, and although costs can add up, individual components won’t break the bank. One-third or more of a building’s electrical consumption may go to lighting, and energy saved in lighting also reduces cooling loads.

“I’ll pretty much guarantee that if nobody has tried to upgrade their space in the last 15 years or so, I’ll find cost-effective ways to cut their load in half” with payback of three to five years, says Mark Loeffler, a lighting designer with Atelier Ten in New Haven, Connecticut.

Overlighting is common, according to Loeffler. Standards from 20 years ago called for 50–100 footcandles of uniform, ambient light in spaces such as offices and classrooms. Today, recommendations are for 30–50 footcandles, and there is more focus on good color rendering. Uniformity is recognized as leading to over-lighting, which may be uncomfortable for occupants. Loeffler says that consumption may be cut in half in a classroom by dropping the overall lighting level, focusing increased light on the teaching wall, and delivering a measured amount of light over desks.

Despite these opportunities, Loeffler warns against one knee-jerk response to overlighting: delamping, or removing every other or every third lamp from a bank of fluorescent luminaires. “Delamping was practiced widely in the ’70s in response to the energy crisis,” says Loeffler, “and indicated deprivation rather than thoughtful savings.” In addition to looking bad and leading to occupant complaints, delamping can strain ballasts and lead to premature failure.

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Glenborough Realty Trust’s 33 New Montgomery building in San Francisco was retrocommissioned by Servidyne, yielding an annual savings of $18,497 on its energy bill.

Photo: Glenborough Properties LLC

Loeffler recommends a systematic approach: “First, understand the various uses of a building. Who’s using it, for what, when, what’s the occupancy pattern, so we’re sensitive to the needs of the visual environment.” That analysis will reveal savings opportunities such as whether a space is over-lit, or whether uniform lighting can be replaced with a more inviting and efficient approach.

Replacing lamps, ballasts, luminaires, or all three, can lead to significant energy savings. Relamping is a relatively low-cost choice that may be appropriate, for example, in an area using 35-watt T-8 fluorescent tubes that is moderately overlit. The system could go to 28-watt T-8s, reducing the wattage by 20% without a big loss of lumens. It may be technically feasible in that situation to simply swap the lamps and not the ballasts, but, says Loeffler, it’s a missed opportunity if you don’t switch from old magnetic 60 Hz ballasts that flicker and buzz to electronic ballasts operating at 20,000 Hz. The light fixture may remain in place but should be cleaned. Loeffler cautions that relamping doesn’t always go far enough. “Maybe you need to replace the ceiling and put in fluorescent 2' x 2' fixtures on 10-foot centers rather than every four feet,” he says.

Simple retrofits can also make better use of daylighting. “In some cases the daylight could be improved by better shading or by changing finish colors or rearranging furniture,” said Loeffler. Daylighting sensors make sense in new construction but may not work as well in retrofits, notes Loeffler. Although there are exceptions, like large lobbies, “you really want electric lights to be dimming in response to daylight, and dimming is expensive” and requires careful specification, he says. Less-expensive daylighting sensors that simply turn lights on and off may be too jarring for office environments.

Occupancy sensors for lighting and other electronics are often a much more appropriate technology for retrofits. A wall-switch replacement may be fairly straightforward to perform and, according to Loeffler, can easily offer 25% savings. Manual on – automatic off occupancy sensors for offices usually make the most sense because they avoid unnecessary use when occupants are simply stopping in the office briefly or when they choose to rely on daylight. The automatic-off function ensures the lights go off when not in use. Dual-sensor technology that uses both ultrasonic and infrared sensing prevents most “false offs.”

Anywhere that lighting is always on can be examined for easy savings. George Denise, the property manager for Cushman & Wakefield at the Adobe Towers complex in San José, California, told EBN that turning most of the lights off in the parking garage between 11 p.m. and 6 a.m. has saved $58,000 annually since the project was implemented a few years ago. With the help of a safety officer, Denise found that adequate nighttime lighting could be provided during those hours using just 20% of the electricity.

Elevator operation is not a likely target for quick savings in most buildings (unless the elevators are hydraulic or DC-powered, technologies that are less common today), according to the New York City mechanical system designer Henry Gifford, but elevator lighting is a big consumer. Reducing lighting density, switching to compact fluorescents or LEDs, and even putting elevator lights on motion sensors are good options, says Gifford. Other always-on lighting areas that deserve a look include hallways and stairways. Installing bi-level lighting—with a timer, occupancy sensor, or both—triggering a higher light level, is easy to justify in new construction and is worth a look in these locations.

Mechanical Systems

A step-by-step approach to mechanical systems pays off in any existing building, says John Straube, Ph.D., P.Eng., a consultant with Building Science Corporation. “Once you understand what the mechanical system is, try to understand how it’s operated.” Through that investigation, savings opportunities are likely to become clear. Sound too simple? “It’s often a major mystery,” he says.

Controls and operation

 

lighting.jpg

Atelier Ten helped retrofit the decorative incandescent lighting in the University of Connecticut Student Union lobby with ceramic metal halide and compact fluorescent sources.

Photo: Cannon Design

“One thing to be really worried about is the building controls,” says Straube. Digital controls became common in commercial buildings 10 to 15 years ago. That is plenty of time for components to go awry. “You can get some ridiculous things going on,” Straube says. He cites examples of office buildings where, according to the building operation system, a given fan is turned off every night, when in fact it is stuck on and probably has been for five years. Complex systems that were designed to increase efficiencies can backfire, says Straube, like the economizer damper that is stuck open.

Tia Heneghan, director of sustainable facilities at CTG Energetics in Denver, notes that problems in mechanical systems can be well hidden. Heneghan cited numerous cases where, because an outdoor air sensor had become miscalibrated by as little as 2°F, the mechanical system was cooling air that would ultimately be reheated. Since there would probably be no change to occupant comfort, that kind of problem can easily go undetected; Heneghan recommends including equipment like dampers and sensors in quarterly or biannual preventative maintenance checks.

Many of the most cost-effective improvements to mechanical systems aren’t retrofits but operational changes. “Getting the building engineers to understand their buildings better” is often Heneghan’s goal, she says. At a building in Los Angeles with 42 air handlers, scheduling was a key to unlocking savings. The building’s operators were asked to write down and then verify the operation schedule for the air handlers, said Heneghan. The operators not only verified the schedule, but revised it. “They changed every single air handler schedule by at least 15 minutes and some by up to an hour,” in most cases turning them off when they weren’t needed, she said. “That’s just free money.” In the Adobe Towers parking garage, Denise found that reducing the run-time of exhaust fans from 24 hours a day to an intermittent 10 hours saves $98,000 per year.

As part of her building audits, Heneghan organizes nighttime walk-throughs, which can reveal issues that might not be obvious in the daytime. In one building, an information technology specialist’s job responsibilities led to the slow accumulation in his office of a data center with three or four always-on computers. The cooling load was triggering the air-conditioning system for the whole office at night. After discovering this situation, the servers were moved into a dedicated space designed for that load.

Equipment upgrades

In making any equipment upgrades, the whole mechanical system needs to be considered. “It’s obvious to people that you would install a more efficient boiler,” said Straube. “What isn’t obvious is that you need to be careful when you install condensing boilers that the supply water temperature drops low enough that you get condensation,” he says, referring to the flue gases in the secondary heat exchanger. Missing out on that condensation means wasting at least half of the gains that are possible from the more expensive boiler.

Heat-recovery ventilation or energy-recovery ventilation “makes a lot more sense in retrofits than most people know,” says Straube. Complete ducted heat-recovery systems are available, but so are very small wall-mounted units. For buildings with high ventilation loads, such as schools, adding controls can be inexpensive while offering good returns by reducing unnecessary ventilation. These systems include demand-controlled ventilation, either using a timer or carbon dioxide sensors. “It’s probably worth putting in CO2 sensors,” Straube said.

Ventilation upgrades are a good example of how energy upgrades can be sold to the owner based on other factors. Adding occupant controls to the ventilation system saves energy but also increases comfort, notes Straube, which most likely offers far greater financial return due to gains in productivity.

Building Envelope

Building envelope upgrades are not always cheap, but they can be cost-effective if chosen wisely and integrated with other needs.

Sealing holes

“Find hole, seal hole.” That is how Andy Padian, speaking recently to an audience at the BuildingEnergy09 conference in Boston, summed up his most important, cost-effective advice for energy retrofits. Padian, who is in charge of energy savings at the Community Preservation Corporation, a New York lender for multifamily housing developers, says that large holes in the building envelope are surprisingly common. With smoke-flow testing, with or without pressurization from a blower door, holes due to faulty detailing of windows, eaves, and other problem areas can be found and sealed with caulk or spray-foam insulation. (For more on air barriers see EBN Jun. 2008.)

Many of the worst holes are not only visible to the naked eye, but are intentional. Padian highlights the following examples:

    • Large vents at the tops of elevator shafts are often required by fire marshals for smoke. These elevator shafts work like chimneys, with warm, buoyant air moving up and out due to the
      stack effect, sucking conditioned air out of every floor. A motorized damper may satisfy the fire marshal’s concerns while preventing this waste.

    • For the same reason, chimneys can cause major heat loss, particularly with atmospheric-combustion boilers, for which combustion air is pulled from the room. When replacing boilers or doing any major work on the heating system, use sealed-combustion boilers and explore putting them in the penthouse.

    • Hinged entry doors, particularly in multistory buildings subject to the stack effect, represent big holes. Installing revolving doors instead may make it possible to reduce the size of or avoid those large mechanical systems that often blast vestibules with conditioned air.

    • Gravity vents, which use the stack effect to provide ventilation, more than cancel out any savings in fan energy by exhausting far too much air under typical conditions. A fan and control can be an easy retrofit with immediate cost savings.

Envelope upgrades

Many people think of the walls when considering adding insulation, but “they are not always or even often the thing to do,” says Straube. He notes that the roof and the basement may be more likely places to add insulation. On low-rise commercial buildings, reroofing is a matter of course every 15–20 years. If that time is near, it may be a good opportunity to thicken the foam insulation. “The difference between adding one inch and three inches of polyisocyanurate foam insulation is not even $3 per square foot,” said Straube, and “the mobilization is already paid for” with the reroofing. The basement is usually not the worst area for heat loss, but it is usually big enough, and insulation may be added there without interrupting operations.

Adding insulation to walls can be more cost-effective if packaged as part of a cladding makeover. “It’s very hard to justify adding insulation on the outside of a commercial building on energy alone,” said Straube. “But as soon as you add the fact that the building looks new, that’s worth a lot of money” in increased rents. “The cost of adding foam insulation to the reclad is trivial.” Similarly, energy upgrades can also be cost-effective if combined with safety upgrades such as structural upgrades in earthquake zones, or roof and cladding improvements in hurricane areas.

Windows, especially if they are old and leaky, are one of the most commonly targeted energy upgrades, often without any formal assessment, much to the chagrin of historic preservationists (see EBN Jan. 2007). Whether or not they are worthy of that focus depends on local climate and “if you have a lot of them,” as Straube sums it up.

For more extensive renovations, it may be worth performing energy modeling to identify the role windows play in overall envelope performance and potential energy savings, to determine the most cost-effective and historically sensitive approach. That analysis might reveal some surprises. In an energy analysis of the King Street Station in Seattle, Green Building Services found that while reducing air infiltration through window repairs would significantly improve the envelope’s energy performance, upgrading the glazing would offer only a minor benefit.

If window replacement is not deemed cost-effective or possible within the project’s budget, other options may be worthwhile, including installing low-emissivity (low-e) energy films and installing storm windows (including low-e storm windows, although they can be hard to find).

Many strategies are climate-dependent. In the Southeast, “solar-control films applied to windows can have big bang for the buck, whereas adding insulation doesn’t,” said Straube. Similarly, ventilation is a huge load in hot, humid climates, compared with dryer, moderate zones.

Water Savings

 

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Broken and leaking irrigation components are common targets for water savings, along with systems that spray buildings, sidewalks, and roads.

Photo: Alliance for Water Efficiency

According to Ackerstein, water can be a challenging area for cost-effective green retrofits, because “it’s so darn cheap.” Long-term trends point to higher rates, however, and water isn’t universally cheap. (Climate doesn’t predict price: Boston’s and Seattle’s water is significantly more expensive than Las Vegas’s.)

Faucet aerators are one of the best and most consistent water retrofit items. “You can get so much savings at such low cost” with aerators, says Ackerstein. Many options are available.

Those tempted to install faucet sensors and flush sensors, however, should reconsider. Although these products can offer hygiene benefits in some applications, they do not—contrary to popular perception—save water. Four independent, real-world studies, including one conducted by the Association of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) in 2002, and a 2007 study by the East Bay Municipal Utility District in Oakland, California, have all shown that sensor-activated faucets increase water use by anywhere from 30% to 100%. Sensor-activated flushes on toilets and urinals also increase water use, due mainly to “phantom flushes.”

Leaking faucets and toilet flush-valves are very common and an easy way to save money. A full audit of plumbing systems, looking for leaks and outdated fixtures, and investigating any complaints, is a key step to finding common problems. A simple walk-through is a great way to start, says Ackerstein. He was recently on-site to review a bank in Los Angeles with another consultant. They were surprised to spot a giant puddle at the curb next to the building—at noon on a typically sunny day. They found that whenever the irrigation system was activated, a single broken irrigation sprinkler head was gushing water onto a sidewalk. Ackerstein figured that the sprinkler had been broken for at least two years. In that time, it could have easily wasted 100,000 gallons or more, according to a guide to irrigation maintenance available from the Alliance for Water Efficiency website.

Walking a site while a sprinkler system is operating often reveals areas where water is wasted in spraying sidewalks, roads, or buildings, or where too much water is being applied and is running off. Leaks, sprinkler heads that have been sunk into the ground or tilted, misaligned heads, nozzles clogged by debris, or incorrect pressure can all lead to waste. Just because the landscape is green, Ackerstein says, doesn’t mean the irrigation system is working.

Any examination of landscaping and irrigation should include a look at the owner’s expectations. They may “feel they need to have rotating fresh flowers every couple of weeks, just because it’s become the default,” Ackerstein says. He advises that “many times people don’t care as long as it’s intentional and well-cared for. It can be native and low-water-using.”

Martine Dion, AIA, of Symmes Maini & McKee in Cambridge, Massachusetts, notes that even in areas where water is cheap and irrigation efficiency pays back slowly, it is a visible green measure that can be attractive due to public perception of corporate responsibility. She also notes that reduced maintenance costs and fuel consumption from equipment are significant benefits.

Cleaning

Changing the time of day of janitorial services can offer savings—$68,000 annually at the LEED-EBOM Platinum California EPA headquarters in Sacramento. According to Walter Drane, director of property management for Thomas Properties Group, the property realized those savings through reduced lighting by switching to daytime janitorial cleaning. Noisy work like vacuuming is done at night. Tenants and janitors alike prefer it, Drane said. Turnover on the cleaning staff is extremely low, fewer thefts are reported, and workers’ compensation claims are reduced, possibly because janitors enjoy more human interaction and there are more witnesses to any incidents.

Another simple cleaning item is frequency. “Common areas need to be cleaned sometimes more than once a day,” said facilities expert Sheila Sheridan. “But look at how you’re cleaning your office areas,” which may not require daily cleaning. Renegotiating items like this can offer immediate financial payback as well as reduced energy use from cleaning equipment and lighting and reduced chemical use.

Occupant Health

 

Low-Cost LEED for Existing Buildings v.2 Credits

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As noted above, the financial returns resulting from increased productivity or occupant satisfaction can be far greater than those from reduced operating costs. How do you target those areas?

Investigating complaints and conducting occupant surveys are one way. Understanding complaints and what to do about them may mean stepping into other people’s shoes. When investigating problems in a building, Terry Brennan, a building science consultant with New York-based Camroden Associates, says that he asks people with complaints to walk him through a typical day in their building. Poor indoor air quality is often a source of problems, but Brennan says that stress and nausea can derive from other factors, including poor acoustics and glare. (If you shade your eyes and experience relaxation, you’re probably experiencing glare. That tension in the facial muscles is linked with headaches and sinus conditions.) Fixes may be as simple as reorganizing spaces or installing glare-control devices.

To investigate occupant health, Padian advises owners to “follow the money.” He cites a property management firm that looked at its maintenance expenses for all the buildings in its portfolio in about 15 categories including pest control, painting, and landscaping. A number of buildings were off the charts in those areas compared with similar buildings. The firm has begun investigating those expenses not only because it thinks that money is being wasted, but also because it suspects that the waste of money in those areas indicates overuse of chemicals that could be making people sick.

Getting Help

In any area of operations, getting the right help is crucial to realizing savings. At a big-picture level, hiring a commissioning agent or engaging with an energy service company (ESCO) can be a solid investment. The ESCO industry has developed since the 1970s, and the several large companies that dominate it have been able to find reliable energy savings for facilities year after year. Typically these savings pay for any capital costs over a number of years, and the ESCO often provides the capital itself while pocketing a set amount of the savings.

According to Paul von Paumgartten, director of energy and environmental affairs with Johnson Controls, savings of 60 cents per square foot per year through lighting, mechanical, and other energy improvements are “locked and loaded.” He said that some buildings working with ESCOs are saving $1.50 per square foot per year.

Lighting and energy consultants often point out the obvious, but their insight can also be crucial to avoiding disaster. Energy-efficiency improvements such as insulation upgrades may create unexpected problems in other areas, such as moisture control, since heat loss often mitigates moisture problems. According to Straube, reductions in lighting and ventilation are often warranted, but anything can be taken too far.

Not all help needs to be hired. Vendors of all kinds may be willing to analyze purchasing patterns at no cost to reveal environmental opportunities. Utilities often offer energy-efficiency consulting and incentives because it may be cheaper for them to reduce demand than to add capacity.

Almost anyone can and should be a partner in finding cost-effective green upgrades—including, first and foremost, the operations and maintenance staff. Padian says that his job may be “not to figure out what is wrong with the building but why it hasn’t been fixed in 15 years.” The maintenance personnel may know about a problem, but there may be institutional roadblocks to fixing it. Or, he says, “it’s been fixed 700 times, and the occupants keep disabling the fix because they are thermally uncomfortable” and that hasn’t been addressed.

Heneghan agrees that building engineers are a valuable resource: “Their job is to make it work, and they do a good job of it. When someone comes in and asks questions, they’re full of good ideas on how to make it better.” The same may be true of tenants, occupants, owners, contractors, vendors—or anyone else who is involved in a building.

Continuing Education

Receive continuing education credit for reading this article. The American Institute of Architects (AIA) has approved this course for 1 HSW Learning Unit. The Green Building Certification Institute (GBCI) has approved the technical and instructional quality of this course for 1 GBCI CE hour towards the LEED Credential Maintenance Program.

Learning Objectives

Upon completing this course, participants will be able to:

    1. Define the term retrocommissioning and list at least three examples of how it might help commercial building owners.
    1. List several cost-effective measures for increasing the energy and water efficiency of existing commercial buildings.
    1. Identify four holes in the building envelope of commercial buildings that result from common design strategies.
    1. Describe how maintenance and operations staff can and should be involved in retrocommissioning and building upgrades.

To earn continuing education credit, make sure you are logged into your personal BuildingGreen account, then read this article and pass this quiz.

 

 

 

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March 26, 2009