Buildings account for 40% of the nation’s energy consumption. Homes account for about half of this total. When I was in architectural school 20 years ago, strict and unforgiving professors, aware of this issue, drilled passive design concepts into our idealist minds. Architects, as a rule, are environmentalists, but those who hire us, the developers, are not. Until now that is. It is only recently that clients are finally ready to embrace sustainable, or “green,” design, something many architects have been passionate about since the late 1960’s.


The biggest roadblock to designing greener buildings has been cost which, until recently, did not achieve an appropriate payback time period. Providing air-tight, well-insulated buildings with energy-efficient appliances offers the biggest bang for the buck, however there’s an upfront cost in utilizing the latest technologies to achieve these goals. But sometimes, an old-fashioned and simple design is better than the latest technology. “Passive design” techniques that have been around for ages can be easily implemented for new construction projects with no added cost whatsoever. Below are a few basic approaches that will save a great deal in air conditioning, heating, and lighting expenses over the building’s life as well as at the time of construction.


Consider the orientation of the building to the sun. If the size and shape of the property allow, the longer sides of a building should face north and south with the shorter sides facing east and west. The north side receives no direct sunlight as the south side basks in the sun’s golden rays. To the east and west, the sun is at a low elevation as it rises and sets, so its rays hit the house almost horizontally, translating to more heat gain. The hottest and most detrimental rays are in the late afternoon as the sun sets in the west.


Windows are a double-edged sword when it comes to designing sustainably. They are crucial for adequate day lighting, fresh air, and a view to the outdoors. But even the most energy-efficient windows are like gaping holes in a building envelope when it comes to heat gain and loss. Glass, not to mention the air gaps in window assemblies, transfers heat or cold significantly more than typical wood-framed walls do. Therefore, window placement is critical in passive design.


Windows facing north offer great day lighting with no solar gain, but can result in a ton of heat loss when submitted to northern winter winds in cold climates. Heat gain and loss is easiest to manage on the south side where well-designed shading devices allow the sun’s rays to hit the windows in the winter when the sun is lower in the sky, but protect the windows from direct sunlight in the summer when the sun is higher. Southern windows offer the best of both worlds when designed appropriately, but can backfire big-time when not.


Western-facing windows should be avoided altogether, if feasible, where it is best to place rooms that do not require them such as closets or the garage. East-facing windows should be minimal since the morning sun, although not as hot as in the afternoon, also enters almost horizontally.

Providing low windows on the walls that predominantly receive cool summer breezes, and high windows on the leeward walls permits a way for cool air to enter a building and hot air to escape. Of course, other considerations, like views, are also significant determining factors in window placement and must be balanced with passive design needs.

Heat that is absorbed into the building during the day can quickly escape from the windows during the cold night when it is needed most. To maintain a comfortable temperature at night, a thermal mass can be utilized. This is typically a thick masonry or concrete wall or floor that receives solar gain directly or through glass. Masonry or concrete slowly release the heat it stored during the warm day. This is just one of the several benefits of exposed concrete floors.


Passive design not only helps the environment, it also supports the health and well being of a building’s occupants. Heating and air-conditioning are not as comfortable or healthy as natural ventilation. Many have been overly focused on green finishes like bamboo flooring and recycled glass tile, because those are the things we can see and feel. Finishes are fun, don’t get me wrong. But the biggest impact on our wallets and on the environment is in reducing consumed energy over the life of a building.