HVAC

Q: I have a 10-year-old air conditioning unit in my 2,000 square-foot law office. I don't imagine it's the most efficient system, but it runs well so I'd like to avoid the expense of replacing it right now. Can you suggest cost-effective ways to improve the energy efficiency of an older air conditioner?
-MJD, St. Johnsbury, Vt.

A:
Paul: You're not alone. Since the air conditioning season is short in Vermont, a lot of small business owners have a hard time justifying the cost of new equipment. Luckily, there are quite a few easy, low-cost things you can do yourself to improve energy efficiency - even on an older unit.

Dan: Just sealing and insulating your cooling system properly can improve efficiency by as much as 20 percent. If you have a ducted system, inspect all the ducts and seal any leaks with UL-181 rated foil tape or mastic that remains flexible after setting, backing with fiberglass tape as necessary. We don't recommend the use of duct tape for this type of work, as the adhesive will fail over time. If your ducts run through an attic or crawl space, also have them insulated with foil-faced fiberglass. Keep the outside condenser unit clear of bushes or shrubs so air flows freely and shade it if possible.

Paul: Try setting your air conditioner thermostat to 78 degrees Fahrenheit or higher. You'll save up to 3 percent on cooling costs for each degree you raise the thermostat. And if the option exists, set your unit to recirculate the air, which uses less energy than cooling and dehumidifying outside air.

Dan: If you have a through-the-window or wall unit, make sure the wall opening is properly sealed around all four sides of the unit with weather stripping. No matter what type of unit you have, clean or replace the filters at least once a month during the cooling season and contact a contractor to service the entire unit annually.

Paul: If you ever decide to replace your air conditioning unit, look for one with the highest efficiency rating possible. Central air conditioning systems are rated in terms of SEER (Seasonal Energy Efficiency Ratio) and/or EER (Energy Efficiency Ratio). Currently, we recommend at least 14 SEER / 12 EER for units sized 65,000 Btu/h or less. Window air conditioners are rated in terms of EER and you should look for an ENERGY STAR labeled unit. Efficiency Vermont provides rebates as an incentive for purchasing high-efficiency air conditioning equipment.

Dan: Another way to lower your cooling costs is to replace incandescent light bulbs with fluorescents. Incandescent bulbs generate much more waste heat than fluorescents. In fact, 90 percent of the energy required to light an incandescent bulb is released in heat. That's a lot of wasted energy. A compact fluorescent uses two-thirds less energy and provides the same amount of light. We recently upgraded lighting and air conditioning at a chocolate factory in South Burlington. The owners expect to see huge savings this summer now that the cooling system isn't constantly overcoming the heat of the old light bulbs.

Paul: Rebates are also available for most fluorescent bulbs and fixtures. Visit the Efficiency Vermont Rebate Center at www.efficiencyvermont.com for a complete list of financial incentives available for your business.

Q: I converted a Victorian home into office spaces that I rent to a variety of small businesses. I suspect that tenants' portable electric heaters are driving up my electric bills. I want to make the offices less drafty so that portable heaters are needed less. My tenants want energy-efficient windows. Is that the best solution? What are other ways to bring down electricity use? I don't want to have to keep raising rents to cover rising energy costs and risk losing tenants. - PE, Norwich, VT

Paul:

You're right that portable electric heaters are a big energy user. Each heater could run you as much as $50 in electricity costs per month. You're also right that they're a sign that building improvements are needed to make rooms more comfortable. The most cost-effective energy-saving improvement you typically can make to a structure that was originally built for residential use is to address air leaks that allow outdoor air to enter your building.

Dan:

That's right. Air leaks can make the difference between a comfortable and chilly space and can have a big impact on energy use. Air can enter through gaps and cracks in the attic floor and the ceiling beneath it. Air can also enter around windows, doors, flues, plumbing vents, wire pathways, recessed lights, fans, chimney penetrations and through insufficient or improperly installed insulation. The most accurate solution to air leaks is to bring in an expert to take a comprehensive look at your building.

Paul:

That's also the most financially logical approach to improving the energy efficiency and comfort of a structure like yours. A Home Performance with ENERGY STAR® certified contractor is specially trained to conduct whole-house assessments, make recommendations about air leaks and a range of systems (heating, cooling, ventilation, insulation, water heating and more) and to perform necessary improvements based on your budget. You can find a contractor at www.efficiencyvermont.com/homeperformance.

Dan:

Another big electricity user in your offices is likely to be lighting. Consider using compact fluorescent bulbs (CFLs), which demand as much as 75% less electricity than incandescent light bulbs do. Replace overhead T12 fluorescent tube lighting with High-Performance T8s and you'll get better light quality while using up to 40% less power. You also can install wall-switch occupancy sensors to automatically shut off lights when a space is not in use. Also, let your tenants know that, when it's time to replace office equipment, they'll find that ENERGY STAR qualified products, such as computers, phones, copiers, and water coolers, use less energy than standard models. Your tenants may appreciate knowing that they can help control their rent levels by saving energy.

Paul:

A financial note on new windows: Energy-efficient windows do a great job of reducing drafts and increasing comfort. But the payback period, from energy savings, on the cost of new windows is long. So it's generally not advisable to replace old windows for energy-saving purposes alone. The most cost-effective time to buy high-performance windows is when you're building a new space, putting on an addition, or replacing nonfunctional windows. If you've got windows that work, you're better off, cost-wise, improving them than replacing them.

Dan:

And that's fairly easily done. If the building has storm windows, use them. If not, have them made - they're far less costly than new windows. See that new storm windows have a low-E coating for even greater energy savings. Repair any cracked glazing, run a bead of caulk around frames, and use side-mount sash locks to hold windows firmly in place. Block drafts through sash-weight pulley openings by using pulley seals. Inexpensive window weatherization kits, from hardware stores, add an additional level of protection from the elements.

Paul:

Best of luck with your building improvements. I think you'll find that taking a whole-house approach will pay off both in lower energy costs and in more comfortable tenants who'll want to continue to do business out of your old Victorian.