Basically, some started looking at what takes place during a chiller retrofit. And it was found that not much happened other than the old chiller was taken out and a new one of the same size was put back in. A valuable concept emerged from this examination: if a chiller has to be replaced anyway, it should be done in the most cost-effective and energy-efficient manner possible. That included looking at the whole building as a system when any changes were made to the space conditioning equipment.
The people behind this concept are some of the leading researchers in energy efficiency innovation science in the world, and they’re located at Lawrence Berkeley National Labs (LBNL) in Berkeley, CA. The Building Technologies Department of their Environmen-tal Energy Technology Division focuses almost exclusively on creating highly efficient buildings.
These researchers have designed the Integrated Chiller Retrofit (ICR) program, which is aimed primarily at large commercial and institutional buildings. However, ICR concepts are just as easily applied to a small building that needs a new chiller. Contractors who are well versed in these concepts will be able to provide building owners with some simple yet effective ways to save energy.
Go Through the List
The ICR program encompasses all the steps you should take when performing any comprehensive energy efficiency improvement program. “You look at all the potential for improving energy efficiency from operating cycles through maintenance programs — just changing the on and off times of the chillers, for example. You look at all the conceivable energy efficiency opportunities to reduce load,” says Dr. Charles Williams, supervisor of the Applications Team, Lawrence Berkeley National Laboratory, Berkeley, CA.The best time to do this evaluation, however, is not when a chiller has died and building occupants are starting to complain. Contractors would be wise to suggest an energy audit (either by themselves, if they’re capable, or by outside energy efficiency consultants) during scheduled routine maintenance.
As most already know, the majority of the actual cooling load in many commercial buildings is produced internally, rather than externally. It’s the lights, people, and equipment that produce the heat. So in an integrated chiller retrofit, you look at possible lighting retrofits, or suggest items like solar film or replacement of windows if there is a great deal of heat gain on south- and west-facing windows.
Also, look at the efficiency of air-handling units and consider retrofitting with high-efficiency fan motors. If you’re doing a lot of reheating of chilled air for comfort in some parts of the building because you need more cooling elsewhere, consider better zone controls and variable air volume (vav) systems. Essentially you look at a building just like a performance contractor would. A total performance contractor examines all aspects of a building, suggests retrofits that are cost-effective and that will reduce the energy consumption. If this is done in conjunction with a chiller retrofit, building owners will definitely save energy.
The idea behind the integrated chiller retrofit is to do as much as possible to decrease the cooling load and pay particular attention to energy efficiency measures that will reduce either the intake of heat by the building or reduce the amount of heat generated internally.
Bigger Is Not Better
Williams is quick to point out that one of the major factors involved in an ICR is measuring the cooling load in the building. “You need to calculate the actual size of the chiller or multiple chillers that you’re really going to need in the building. It’s pretty commonly understood that the majority of chillers in U.S. buildings are oversized. Quite often, commercial chillers are running fairly low on their efficiency curves. If they’re 70% to 80% loaded or better, they’re much more efficient, but the efficiencies typically don’t run close to that.”But there’s more than just sizing the chiller: It is essential to configure the chiller and its controls so the chilling capacity follows the load well. For example, if a building relies on one big chiller to handle all its needs, that chiller is almost always going to be running at a load below the optimal efficiency curve. A good idea might be to replace one large chiller with multiple smaller chillers, so on days where just a few spaces need cooling, a smaller chiller could be used to handle those needs.
Of course, it may not be inexpensive to do an integrated chiller retrofit; however, many buildings already face a considerable capital cost burden if they have to replace a chiller. If they combine the whole-building retrofit approach, they may have so much savings available that they could actually convert that capital cost burden to a positive cash flow. Or at the very least, make it an investment that would pay for itself in a relatively short time.
If an ICR can substantially reduce the payback enough for the project, it can be outsourced and financed by an energy savings performance contractor. A chiller replacement often has such a long payback that energy services companies (ESCOs) or customers may be reluctant to enter into a contract of sufficient length to pay off that chiller.
“Modern chillers are more efficient than those built 20 or 25 years ago, but you really need the whole package to make it a 5- to 7-year or less payback package of energy conservation measures,” says Williams.
The bottom line is that an integrated chiller retrofit just makes sense, especially today when energy costs are ratcheting upward every day. When it’s time for a new chiller, it’s also time to take a look around a building and suggest improvements that will benefit the owner’s profitability — immediately.
For more information, check out LBNL’s website at http://ateam.lbl.gov/coolsense. There you’ll find detailed information concerning ICRs, as well as case studies that document how ICRs have benefited buildings around the country. Technical tips and analytical software tools are also available.
Sidebar:
Solar Energy Rebates Available
COCOA, FL — The Florida Solar Energy Center (FSEC) is offering rebates for photovoltaic (PV) system installations on residential buildings within the state. Funding is provided by the Florida Energy Office, Department of Community Affairs. Florida residents, builders, developers, government agencies, and electric utilities are eligible for the rebates.
Qualified applicants receive $4 per installed watt up to a maximum of $16,000. The system must be connected to the utility grid and produce at least one kilowatt to qualify. A 4-kilowatt system for around $40,000 can provide about half the energy needs of a 2,000 square foot home, according to FSEC.
For more information, call 321-638-1455 or send questions to rebate@ fsec.ucf.edu (e-mail).
Publication date: 07/09/2001
