Your drafty old apartment building may be the ideal place to put modern high-performance ideas into practice.

A thoughtful green rehabilitation can cut your gas and electric bills by a third or even in half. The rehab will also make the apartments healthier places to live in and dramatically more comfortable – and doing the job does not have to cost any more than a conventional rehab, according to experts like Chris Benedict, a New York-based architect who specializes in green (or high-performance) buildings.

Much of the pioneering work in tuning up old buildings has been done by small, nonprofit affordable housing developers, but their ideas can easily be applied to Class B and Class C market-rate apartment buildings.

When green-minded nonprofits rehab a building, their work typically only costs between 2% and 4% more than a conventional rehabilitation, according to six case studies reviewed by New Ecology, Inc., as part of its report, The Cost and Benefits of Green Affordable Housing.

In Chicago, a gut rehab of a building to high-performance standards costs $75 to $100 per square foot, or $75,000 to $100,000 for a 1,000-square-foot apartment, according to Paul Knight, an architect for Domus Plus, based in Oak Park, Ill., and an energy consultant for the Illinois Energy Efficient Affordable Housing Construction Program.

That’s only about $2,500 more per unit, or 2.5% to 3.5% more than a conventional gut rehab, even though Knight sometimes includes expensive technology like solar panels in his rehabs.

Most of these rehabs don’t try to meet the strict Leadership in Energy and Environmental Design standards created by the U.S. Green Building Council. However, by reusing an old building, these projects achieve many of the key goals of the green building movement and still manage to help reduce operating costs.

Getting started

The first step is to assess the building as one entire system and to look at how each part of that system affects all of the other parts. This helps owners identify opportunities to improve the building.

For example, replacing drafty windows will lower the cost of heating the structure. The new windows might even make it possible to install a smaller, less expensive heating system. The new windows could, however, expose ventilation problems. “The leaky windows might have been the only source of fresh air,” said Kim Vermeer, principal for Boston-based Urban Habitat Initiatives.

Green or high-performance building requires a more thoughtful approach to construction. The core ideas aren’t embodied by expensive, flashy technologies like green roofs or solar panels. Instead, high-performance building is all about building science, Vermeer said.

It begins with stopping the uncontrolled flow of air into the living space. Consider installing windows with an Energy Star rating, which means they meet government criteria for energy efficiency.

While these top-rated windows can sell for as little as 50 cents per square foot more than standard models, they can be as much as 40% better at insulating an apartment. If you choose not to replace the windows, make sure they’re operating properly and close tightly.

Also make sure that air can’t slip from one floor to another inside the building. Heat can rise from lower apartments to higher apartments through openings as wide as a stairwell or as narrow as the space around a pipe. That’s why in many buildings the apartments on the lower floors are cold while the top floor is so overheated that tenants open their windows on frigid nights.

Sealing these openings is required by most building codes, but many builders fail to do the work, Benedict said. Sealing these holes will also help control roaches and other pests.

Contractors can find these openings and caulk them shut by conducting what Knight calls a “blower door test.” He closes the windows and places a specially built fan over the door of the apartment. While the fan pulls air out of the apartment, Knight uses his fingers to feel the air rushing in through cracks and seams. A gauge on the fan also measures how much air is leaking into a unit by measuring how much air the fan can pull out.

Buildings with poorly installed insulation are also less energy efficient. Check the attic and inside the walls as much as possible: Insulation should have no large gaps and should be in direct contact with whatever it is meant to be insulating. It is worthless if frigid air can get underneath it, in the same way a winter coat won’t keep you warm unless you put it on and zip it up. Pipes and vents for heating and cooling also need to be well sealed and well insulated.

Effective heating systems

Once air no longer leaks into the apartments, your building may be able to use a smaller heating system. Many buildings that have undergone green rehabs save thousands of dollars when it comes time to replace their heating systems.

Typically, these savings more than pay for the added cost of Energy Star windows and other improvements.

Green building experts also recommend installing heating systems that can be individually controlled for each apartment, if possible. This is especially helpful if it has proven impossible to stop warm air from rising to the top of your building: With individual thermostats, tenants use only as much heat as they need and don’t get on the phone to management whenever their apartments are too hot or too cold.

If you choose to keep your building’s original heating system, make sure the system is well maintained and operating within the manufacturer’s specifications. A qualified professional should inspect, clean and tune up the system at least once a year.

Many developers rehab their heating systems a little at a time. Keep track of older, inefficient equipment, including water heaters and elevator motors, and when a machine nears the end of its useful life, replace it with a more efficient one before it breaks down.

Owners can find tips on choosing heating and cooling equipment, along with lots of other energy-saving suggestions, ratings and guidelines, at For help with pumps and motors, download the Department of Energy’s (DOE) Motor Master program at

Better air quality stops mold and allergens

Many developers fail to put much thought into ventilation, even after they have gone down the whole checklist of energy-saving measures at their buildings. That’s because ventilation is not an obvious way to save on construction costs.

Also, it may seem counterintuitive to properly seal an apartment only to blow air in and out. But experts say that apartments that control the flow of air are much cheaper to heat – because the heat is spread evenly through the unit – in addition to being much healthier to live in.

A well-ventilated studio or one-bedroom apartment should receive 30 cubic feet of fresh air per minute, plus another 15 cubic feet of fresh air for each additional bedroom, according to Vermeer.

When rehabbing a building, make sure each unit has a ventilation system that draws fresh air through the entire living space. In many buildings, for example, fresh air pumped into the hallways slips under the front doors to enter the apartments. Stale air is blown outside by the bathroom fan. The fan should be a quiet model that runs all the time. This will also help keep mold from growing on the bathroom walls by keeping down humidity in that room.

Ventilation is also important to expel gases like the carbon monoxide produced by gas ovens and stove tops, according to Bruce Davis, research director for Advanced Energy, based in Raleigh, N.C.

Range hoods should expel at least 100 cubic feet per minute to the outside. Otherwise, the fan simply “takes the gases and blows it back in your face,” Davis said. The fan should also be quiet enough so that tenants will use it.

Boilers and furnaces should be sealed-combustion units instead of open-flame systems that depend on high air pressure inside the building to force fumes out through a chimney. Otherwise, if the air pressure drops inside the building, air could be pulled into the building past the open flame, causing carbon monoxide from the furnace to diffuse throughout the apartments.

Managers might not even know if they have this particularly nasty problem. Davis recommends testing apartments with a low-level carbon monoxide detector.

Construction materials can also emit unhealthy fumes. Paints, strippers, varnishes and waxes can give off methylene chloride, benzene or other volatile organic compounds (VOC); the glue that binds sawdust into plywood often gives off formaldehyde. These gases have been linked to a host of allergy-like symptoms in addition to cancer.

Product manufacturers often offer healthier versions of these products, frequently at no extra cost. Of course, using healthier products won’t save any money. But developers might rest a little easier after they reduce potential health risks in their buildings, not to mention the potential for health-related lawsuits.

Wall-to-wall carpeting can also give off noxious fumes and trap dust and allergens in the corners of a room or under furniture, where it’s hard to clean. These carpets need to be replaced every few years, and often cost more than $1 per square foot. In contrast, prices for longer-lasting wood flooring start as low as $2 per square foot. Renters in many markets are showing a preference for wood floors, which last much, much longer than carpet – so you can save money while creating a healthier environment for your tenants.

Save on electricity

Most green developers buy appliances with the Energy Star rating, even though the benefits from the appliances flow to the tenants, saving them money on their electric bills. These appliances are slightly more expensive, but often use about a third less energy, according to the DOE.

And whether your water heater operates on electricity or gas, don’t let the water temperature rise above 120 degrees. This is both an energy-saving and a safety issue.

Installing energy-efficient light bulbs is an easy way to cut a building’s lighting bill by up to 75%. Vendors like now list compact fluorescent bulbs for less than $2 apiece. That’s about three times the cost of incandescent bulbs, but because compact fluorescents last much longer, the cost of the hardware is roughly equivalent, experts say.

However, product testing reveals a tremendous range in the quality of light produced by compact fluorescents, even between bulbs created by the same company. Many produce attractive light, but some do not. Be sure to try out lights before ordering hundreds for your building.

Fixtures can also help. Hotels put compact fluorescent bulbs behind paper or cloth shades that soften the light and improve its color.

Install water-saving devices

Water is rapidly becoming another large expense for landlords. Courtney Moriarta, senior engineer for Steven Winter Associates, Inc., a company of green building consultants in Norwalk, Conn., recommends installing showerheads that use two gallons per minute or less and faucet aerators that use one gallon per minute or less. The fixtures cost the same as regular fixtures. However, she recommends that developers test the hardware in their own homes before subjecting their residents to them.

Building codes now require low-flow toilets that use only 1.6 gallons per flush. Many tenants have had a variety of bad experiences with toilets like these. For a list of low-flow toilets that work well, read Maximum Performance Testing of Popular Toilet Models, a report available at

Water-saving ideas also extend outdoors. Moriarta recommends that developers choose drought-resistant plants to landscape.

USGBC sets new standards

The U.S. Green Building Council and the Congress for the New Urbanism have created a set of standards designed to help make whole neighborhoods more sustainable. The Leadership in Energy and Environmental Design (LEED) for Neighborhood Developments rating system should launch in late 2007.

Also in early 2007, the council should launch its LEED for Homes rating system, targeted at single-family homes and multifamily buildings up to three stories. Taller multifamily buildings will still struggle to fit in under the LEED for New Con-struction standards, which was originally designed for commercial office buildings.

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