The revival of passive design

RMI's Passively Designed Headquarters, Snowmass, Colorado.

Architects once designed solely within the constraints of the environment.

They examined each new building site, ensuring, among other things, a new construction would have optimal orientation to the sun.  

The amount of daylight able to reach the center of a room determined a building's width while air circulation needs dictated the height of ceilings. Air, of course, came from operable windows. 

Consider the Anasazi Indians. They constructed high-mass adobe dwellings in southern-facing caves in the American West. In the winter, when the sun follows a lower path, their designs harnessed the sun's direct heating energy, and during the summer, when the sun follows a higher path, rock overhangs blocked heat gain and the sun's harsh rays. 

Though they didn't realize it at the time, the Anasazi employed passive design -- using the sun's energy to light, cool, heat and ventilate a building's interior.  

But something changed with the advent of mass-produced electricity. 

In 1882, Thomas Edison's first utility plant opened to supply 800 incandescent lamps worth of energy to surrounding customers and from that point on buildings' use of fossil fuel-based energy began to skyrocket. 

According to analysis from the Energy Information Administration, buildings now account for 70 percent of the United States' electricity consumption.  They are responsible for 40 percent of the country's carbon dioxide emissions, more than any other sector, including transportation. 

 
Energy drain
Buildings experts at Rocky Mountain Institute believe the development of technologies like electric lights, fans and mechanical heating/cooling systems seemed to free users and designers from the constraints of weather, prevailing winds and daylight. 

Architects could create designs confident engineers would make them possible. And engineers could make it possible, though it often required enormous amounts of energy. 

As time went by, architects no longer needed the knowledge or practice of passive design once crucial to a building's functionality. Gradually this knowledge became dormant. 

The energy crisis of the 1970s brought new attention to energy prices, fuel supplies, and environmental pollution.  By that time, contemporary methods of building design and construction had become entrenched, resulting in, for example, massive amounts of heating and air conditioning being used to supply inefficiently designed, energy guzzling skyscrapers. 

Even the growth of the "green" building movement of the last few decades was not enough to challenge the status quo. 

But that is changing -- quickly.  The energy and climate change crisis and with it increased social and corporate awareness are driving a return to an older attitude to design and construction -- incorporating what were the norms of the pre-electric past.

Passive design solutions
By re-learning how to use passive design to our advantage, we can dramatically cut buildings' energy usage. For example:

• Daylighting lowers electricity use and minimizes cooling loads, while also improving visibility, health, and productivity.

• Thermal mass, such as the concrete flooring of Rocky Mountain Institute's passively designed 4000 square foot headquarters in Snowmass, Colorado, can keep rooms warm even after the sun sets.

• Optimal building orientation can maximize the sun's power, and proper landscape design (as simple as locating near trees) can contain strong winds or reduce cooling loads.

RMI's Built Environment consultants believe buildings can cut their energy use by more than 70 percent (more than the DoE estimates) and are beginning to design structures that produce more energy than they consume. 

Passive design plays a major role in all this because the constraints imposed by the environment -- from temperature to lighting -- have some value after all. 

In next week's Environmental Lovins, we'll look at some modern structures that combine passive design with technical know-how, creating superior living spaces without the negative by-products. 

Monica Sanford is an intern on the Built Environment Team and Maria Stamas is an analyst at Rocky Mountain Institute.