For decades, Hawai'i homes were built with little thought toward how to cool their interiors. The most popular solution to warm weather was air conditioning.

It was an inefficient remedy.

Air conditioning cooled the house even as the sun baked it. Homes weren't designed to keep the chill inside and the heat outside.

Then, in 2000, a housing boom on the sun-baked 'Ewa plains prompted a push toward environmentally friendly homes.

From new subdivisions to custom houses to remodeling jobs, environmentally friendly homes are becoming more commonplace, sparked by recent building codes and consumer awareness that grew out of the boom. Construction materials that better shield homes from heat have contributed to the shift.

Advocates say these "green built" homes can save consumers hundreds of dollars a year in energy-related costs and help reduce the state's dependency on oil. But even though experts say Hawai'i offers a nearly perfect climate for energy-efficient construction, widespread acceptance has not been reached.

"We live in one of the most comfortable climates in the world and too often we are more comfortable standing next to our buildings than in them," said Stephen Meder, an assistant professor at the University of Hawai'i School of Architecture and the director of the university's Center for Smart Building and Community Design.

Development in 'Ewa remains the hot spot of residential building on O'ahu and is the birthplace of the new energy-efficient push. And the building boom will continue: recently, 10,000 to 15,000 new homes have been proposed for the area by the Schuler Division of D.R. Horton Inc.

But energy-conscious homes were not developers' main concern when they started building on the 'Ewa plains in the late 1990s and 2000, said Howard Wiig, an energy analyst with the state Department of Business, Economic Development and Tourism. Thousands of homes went up — including many on the flight path to Honolulu International Airport — that relied on central air conditioning to keep them quiet as well as cool.

"It rang alarm bells with us," Wiig said. "We saw a tremendous increase in the use of electricity."

And it was worse for neighbors without any climate control. Locked up all day, their homes would be too hot to inhabit in the evening, Wiig said.

"We had reports of people eating their dinner out on TV trays in the driveway with a TV propped on the hood of a car," he said.

The situation "became so dire," that DBEDT was able to convince the City and County of Honolulu in 2001 to adopt the first residential energy codes in state history. The state had been trying to do this for 20 years, he said.

"We have been working on this for so long and the concept is catching on," Wiig said. "And the fact that electricity is going up is definitely on our side."

The new code required builders to shield roofs from the sun by choosing from several solutions, including radiant barriers that reflect heat, insulation and highly reflective roofing material, Wiig said.

"The builders did not object," he said. "You cannot say they embraced it. They did not object."

DBEDT estimated in 2001 that a home on O'ahu built to conserve energy and fitted with a solar water-heater, energy-saving appliances and lighting could save a family $831 to $1,131 a year. Under the current rate, that savings has jumped to $1,196 to $1,628 a year.

"With the cost of oil going up, everybody is going to want to conserve energy," said Karen Nakamura, the chief executive officer for the Building Industry Association of Hawai'i.

DEMAND FOR GREEN

Many home builders in the state are using energy-efficient materials and designs even though it can increase the cost of a home, Nakamura said.

The building association's membership includes commercial builders responsible for 80 percent of the new homes in Hawai'i and all of them employ "green building," Nakamura said.

It's part of the association's Hawaii BuiltGreen Home Program, an education effort aimed at builders and the public that also began in 2000. The trade association has produced a list of 248 things a builder can do to create a more energy-efficient home and more than 1,000 homes have been built in the past five years using green guidelines.

Builders are given a rating based on how well they follow the list — and consumers want to know who those builders are, Nakamura said. People call her every week.

"Now we have consumers who are very well-educated about it and some of them are demanding it and are willing to pay for it," Nakamura said.

The cost of a home can be 2 percent to 10 percent higher, depending on the number of things a builder has done to increase efficiency, Nakamura said.

But those traits can drop the temperature in a home by almost 10 degrees, which means an environment that rarely needs air conditioning, Nakamura said.

And that means a lower electric bill, she said.

Builders were skeptical when they first heard about building green. They were concerned about costs and public reaction. Some tried it anyway and were pleasantly surprised, Nakamura said.

"When their customers moved in they said 'Wow, I really like my house, it's really cool,' they realized the value of building green," Nakamura said.

There are various guides available from DBEDT and the BIA that can be used to build a cooler home. Some are simpler than others, but all rely on a basic philosophy that combines new building materials and common sense, said Meder, the UH architecture assistant professor.

"Reduce the heat getting in and find a way to ventilate the heat that got in," he said.

COOL TECHNIQUES

So-called "passive cooling strategies" can eliminate the need for central air conditioning.

Windows and screen doors can be placed to take advantage of prevailing winds whenever possible and a light color choice for roofing material and exterior paint can reflect heat. Walls exposed to strong sun can be shielded by roof overhangs and trees but they can also be built with material that reflects the heat. Asphalt and concrete areas have been found to be as much as 30 degrees cooler when shaded, the state claims.

Radiant barriers in a roof and walls can reflect, rather than absorb, the sun's heat. These barriers are made of thin sheets of polyethylene air bubble packets sandwiched between thin layers of highly reflective aluminum foil.

It costs about 80 cents a square foot to install but will eliminate about 80 percent of the heat getting through, Meder said.

Similarly, insulation placed in an attic will keep heat from being transferred to the room below.

Add mild air flow from windows and bodily comfort increases, even on a hot day.

That same pounding sun that can sizzle rooftops to 150 degrees can be used to trim 40 percent off an electric bill if the homeowner installs a solar water-heater. For years, it has been the poster child of energy-efficient homes and is a proven resource able to save a family of four about $625 a year.

Islanders warm up to green-home design

Reach Mike Gordon at mgordon@honoluluadvertiser.com.