Historic Building Exteriors & Passive Mode Design

"Originally, before the Thermostat Age, the places we built and buildings we built had no choice but to be green, otherwise people would freeze to death in the winter, die of heat strokes by summer, starve to death, or other really bad things would happen to them. Today, as we are working to re-learn how to live sustainably, much of the focus is on the gadgetry of green: Gizmo Green. This notion that we can simply invent more efficient mechanisms, and throw in some bamboo to boot, is only a small part of real sustainability."
- Steve Mouzon, The Original Green

Historically, builders relied on the structure to help provide comfort to inhabitants. This practical approach has produced many of the historic architectural features we love about old buildings.

Porches, balconies, vestibule entries, courtyards, operable windows and shutters were not arbitrary design features, but rather devices to improve the comfort of the building's occupants. Today we celebrate these features in historic homes, but we must remember that their purpose far exceeds their aesthetic value. These features, if properly used and maintained adapt to weather fluctuations, actively reducing energy consumption and costs!


Operable historic windows are not only a key feature of a building's exterior, but can function in accordance with the weather. Yet historic windows are often the first historic feature to be replaced in the interest of "energy savings".

Ironically, operable historic window openings provide natural daylight and ventilation, qualities that green construction aims to emulate. These windows help reduce the cooling load by catching natural breezes and providing ventilation within the interior. For example, opening a double hung window's upper sash allows hot air to escape, thus increasing summer cooling.

Designed before the use of artificial lighting, historic windows were also designed to maximize daylighting. Many historic windows employ large openings or features like transoms that can filter light further into building interiors.

Awnings, overhangs and exterior shutters are historical building features that, when properly used, can assist historic windows in providing comfort to the interior. By providing shade from summer heat, these features help further reduce the cooling load, while still permitting daylight . The use of awnings, overhangs and shutters on the south and south west facades can have a tremendous impact, blocking out harsh solar exposure and lessening fluctuations in heat gain. They also diminish heating load in the winter by acting as partial insulation on the north and northeast sides where the building receives little direct sunlight.

Another feature of the Lowcountry are violent storms and operable shutters protect historic windows and have protected them for hundreds of years.


Preservation Brief 44: The Use of Awnings on Historic Buildings

U.S. Department of Energy: Energy Savers: Awnings

U.S. Department of Energy: Energy Savers : Overhangs

U.S. Department of Energy: Energy Savers: Shutters

The average house includes features capable of responding to the environment, and if properly used, owners can realize a dramatic reduction in energy use and associated costs. The window of the turret in this house is opened, to release hot air that rises (the stack effect).