If buildings are living organisms, as energy-efficiency gurus like to say, then the Portland Opera's three-floor headquarters and rehearsal space in Southwest Portland is bipolar, vacillating between frenetic activity and somnolence.

PORTLAND — If buildings are living organisms, as energy-efficiency gurus like to say, then the Portland Opera's three-floor headquarters and rehearsal space in Southwest Portland is bipolar, vacillating between frenetic activity and somnolence.

In either state, its respiratory system wheezes along, inhaling outside air; heating, cooling and filtering it; pushing it through the ductwork; then exhaling the exhaust.

On a recent Friday morning, the company is at rest. Its cavernous rehearsal spaces are comfortably heated but empty except for conductor Robert Ainsley, who sits at a piano running through the score for an upcoming production.

In the costume shop, a single stitcher is making alterations, her radio turned up to carry over the hiss of a ventilation system in the floor. The box office and third-floor office space quietly hum as the sales and development staff bring in the dollars that make the opera sing. But on the entire second floor, leased to city of Portland engineers managing the Big Pipe sewer project, only two workers are pounding their keyboards under a fluorescent blaze.

"We try to get them to turn out their lights when they're not here," said Chuck Ely, the opera's facility manager, "but they're not real good about that."

And that, in a nutshell, is the ongoing problem — and opportunity — of energy efficiency.

Almost 70 percent of U.S. energy consumption takes place in buildings or homes, and by some estimates, about 50 percent of that energy is wasted. Even after years of subsidies and earnest awareness campaigns, that waste represents a vast opportunity if it can be unlocked. The technology is there. Upgrading building systems to save energy often costs a fraction of what it takes to generate the equivalent number of kilowatts from a new fossil-fuel power plant. Indeed, experts say many of the lower-cost measures pay for themselves in months.

Conservation also reduces greenhouse gases and pollution. It creates well-paid jobs in the trades. And it improves cash flow for business and building owners.

The opportunities are virtually everywhere — even in buildings already doing the right things.

"We can walk into a building where they've spent hundreds of thousands on energy retrofitting and be confident we'll find a 10-percent energy savings," said James Crowder, chief executive of AirAdvice, a small outfit in Portland that deploys sensors to monitor and analyze commercial buildings' performance. "It's almost a given. Typically it's between 10 and 30 percent."

Oregon is the third-most energy-efficient state, according to an October report by the American Council for an Energy Efficient Economy, a Washington, D.C., think tank.

Officials with the Energy Trust of Oregon, a nonprofit that subsidizes efficiency measures, claim it is capturing all cost-effective energy savings. They say the efficiency measures the ETO has helped fund though surcharges on utility bills will save consumers more than $1 billion over time, after deducting the cost. The energy savings will offset the need for at least one new power plant and curb 2.5 million tons of carbon emissions — the equivalent of taking 430,000 cars off the road.

Yet the ETO's figures show that only 18 percent of customers follow up and implement efficiency measures recommended after completing energy studies or audits of their homes and buildings. Penetration is highest for commercial office buildings, but it's still less than one-third overall. That squares with efficiency contractors and property managers, who say only a fraction of customers follow through on audits.

Part of the issue is the fact that energy is still relatively cheap in the Northwest. Building and business owners, even those inundated with offers, don't see the advantage of tying up capital and staff when they can concentrate on their core product. Depending on lease arrangements in a given building, the costs and benefits of energy-efficiency projects also may flow to different parties. That complicates things, as does the fact that many building have multiple owners, each with their own return requirements.

Then there's the economy. The Energy Trust increased its incentives by 25 percent to entice building owners after seeing scores of projects canceled or delayed last year.

"We have a lot of owners where vacancies are up, rents are down, and now's not the time to do it," said Dave Hamilton, executive vice president of property management for Norris & Stevens, which manages 7.5 million square feet of commercial space in the Portland area.

Those who follow through go for the low-hanging fruit, the low-cost or no-cost measures that offer an immediate payback — while frequently putting off deeper retrofits that fundamentally change a building's performance and are likely to have a more dramatic financial impact over the long term.

"It all comes down to return on investment," said Susan Steward, executive director of the Building Owners and Managers Association of Portland. "When it comes to the big-ticket items, what I continually hear from members is that 'it doesn't pencil.'"

The Portland Opera is a unique organization, but its approach to energy efficiency reflects many of the opportunities and hurdles in the market today.

The opera bought its 30,000-square-foot building, the former home of KPTV (12), two years ago. The main attraction was rehearsal space, two big blocks of it, with separate spaces for the costume shop and administrative offices and an entire floor that the opera could lease to third parties.

The new owners quickly discovered that the space was fine to keep a TV station's systems running but not designed for comfort or energy efficiency. In the summertime, temperatures inside the south-facing windowsills soared above 100 degrees, while in the winter it was almost equally cold on both sides of the glass.

The opera spent $90,000 — raised through donors — to replace windows on three sides of the building, install a new control system for the heating and ventilation system and complete minor lighting improvements such as motion detectors in the restrooms. Since the building is sandwiched between the entrance to the Big Pipe and a new light-rail project, it also was focused on noise reduction and air quality.

"We bring in all these artists," Ely said. "It costs a lot of money, and we don't want them getting sick."

The initial investment yielded energy savings of almost 20 percent.

In late October, the opera brought in its outside maintenance contractor, MacDonald Miller Facility Solutions, to audit the building's performance. Tom Albers, a MacDonald Miller manager, reviewed how staff and performers used the building and how the facilities manager used his control system. Then he walked through and set up a temporary network of AirAdvice sensors to monitor temperature, humidity, light and air quality. During his tour, Albers said there were no telltale signs of major energy waste, nothing obvious.

Indeed, the opera already had spent more on upgrades than most small-building owners contemplate or can afford. And its operations managers have been emphasizing efficiency.

Yet Albers' report concluded — conservatively, he says — that by spending an additional $21,000 on a variety of efficiency measures, the opera could cut a third more of its electricity use, saving $19,000 a year.

"If the program were to yield that, we'd be down around 50 percent of our energy use" since 2008, said Valeria Ramirez, director of business operations at the opera. "That seems a bit of a stretch to me, but I like the number. It's a big number"

The bulk of those savings — $13,000 — could be generated with a nominal, $1,000 investment to tune up the control system with new temperature parameters, reduce ventilation and shut off the lights on nights and weekends.

The payback on those measures: less than one month.

Another fix — putting variable frequency motors in its air supply units — could save an additional $5,600 a year. The upfront cost would be $20,000 after an Energy Trust subsidy, putting the payback at 3.4 years.

That's right in the supposed sweet spot for conservation measures. But like other businesses, the opera is reluctant — at the moment — to part with the capital.

It's a dilemma energy-efficiency experts have faced for decades: how to motivate investments that seem eminently sensible, yet don't reach the top of a customer's priority list. In theory, it makes sense for utilities to invest in the energy efficiency of customers' homes and buildings rather than new power plants, right up to the point that the cost surpasses new generation.

In practice, it's not that simple. Customers need to be committed, monetarily and managerially, to make it happen.

"Retrofitting old buildings and systems is hard work," said Bob Jenks, executive director of the Citizens' Utility Board. "It requires the owner to participate and desire the investment. They have to invest not just some of their own money but some of their intellectual capital and management time. They have to agree that this is a priority worth taking at this time.

"That is a huge barrier to overcome."