 Heavy masonry walls and few windows serve to maximize warmth inside. Photo: HABS collection, NPS. |
High thermal inertia is the reason
many older public and commercial buildings, without modern air conditioning,
still feel cool on the inside throughout the summer. The heat from the
midday sun does not penetrate the buildings until late afternoon and evening,
when it is unoccupied.
Although these characteristics may not typify all historic buildings,
the point is that historic buildings often have thermal properties that
need little improvement. One must understand the inherent energy saving
qualities of a building, and assure, by reopening the windows for instance,
that the building functions as it was intended.
To reduce heating and cooling expenditures there are two broad courses
of action that may be taken. First, begin passive measures to assure that
a building and its existing components function as efficiently as possible
without the necessity of making alterations or adding new materials. The
second course of action is preservation retrofitting, which includes altering
the building by making appropriate weatherization measures to improve thermal
performance. Undertaking the passive measures and the preservation retrofitting
recommended here could result in a 50% decrease in energy expenditures
in historic buildings.
Passive Measures
The first passive measures to utilize are operational controls; that
is, controlling how and when a building is used. These controls incorporate
programmatic planning and scheduling efforts by the owner to minimize usage
of energy-consuming equipment. A building should survey and quantify all
aspects of energy usage, by evaluating the monies expended for electricity,
gas, and fuel oil for a year and by surveying how and when each room is
used. This will identify ways of conserving energy by initiating operational
controls such as:
lowering the thermostat in the winter, raising it in the summer
controlling the temperature in those rooms actually used
reducing the level of illumination and number of lights (maximize
natural light)
using operable windows, shutters, awnings and vents as originally
intended to control interior environment (maximize fresh air)
having mechanical equipment serviced regularly to ensure maximum
efficiency
cleaning radiators and forced air registers to ensure proper operation
The passive measures outlined above can save as much as 30% of the energy
used in a building. They should be the first undertakings to save energy
in any existing building and are particularly appropriate for historic
buildings because they do not necessitate building alterations or the introduction
of new materials that may cause damage. Passive measures make energy sense,
common sense, and preservation sense!
"Conserving Energy" an Historic Preservation Brief
