Energy Efficiency and Panelized Construction
The efficient use of energy has been a priority for the building industry for a long time, but recent regulatory changes and increased market demand have reinforced the need for constant improvement. Our customers are demanding it and the government, at all levels, is requiring it. One of the best ways to increase the energy efficiency of building new homes is through the use of panelization and roof sheathing selections.When using wall and floor panels manufactured off site, a much more sealed and efficient building envelope can be realized. In Sweden, panels produced using The Swedish System are required to pass a government test of zero air penetration of the structure at a 50-mile-an-hour wind. Such a standard can be met here using the same system or a somewhat lesser standard can be met using others; either way superior performance can be delivered. The key benefit delivered by properly produced panels is reduced air infiltration through a much tighter building envelope seal delivered from:
- Fewer exterior sheathing seams through the use of 4x10 or greater sheathing on all exterior walls, shear or not;
- The use of KD lumber, maintaining tighter fits and delivering much less settlement, shape changes and subsequent leakage;
- Much more accurate stud, module and sub-assembly cuts for better fitting panel-to-panel;
- Much reduced or eliminated sill seepage, with Plate Gasket seals between exterior walls and foundations, as well as between walls and second floor deck; Equally important, these gaskets should also be used between wall panels end studs, where they are joined;
- The use of a computer controlled saw and when possible, the use of engineered lumber, more precise cuts for exterior window and door openings and therefore more accurate openings with less leakage;
- Quality Jeld-Wen or other Energy Star windows with Low E glass installed in the factory and flashed properly under controlled conditions. This should include the use of expansive foam in the window and door openings between the windows/doors and the frame.
Additional energy efficiency benefits include:
- Better quality control overall through off-site manufacturing in controlled conditions;
- Additional points in the builders LEEDS certification process, as well as meeting individual city or county development requirements;
- Far fewer people driving to the factory than to the job site during framing phase;
- Much more efficient use of energy transporting material, as panels are a dense, high-value product that require fewer trips, then a series of material deliveries required to site build the same structure;
- Significantly lower waste, 3% in the factory (most recycled) vs. 17-22% on site. This avoids the costs of producing materials and product that will just be wasted on the job site and then hauled away.
An even greater improvement in building envelope seal and heat retention is possible when, in addition to using properly constructed wall and floor panels, radiant barrier plywood or OSB is used to sheath the roof trusses. The added cost is minimal and the energy savings is significant. If the builder is reluctant to incur the cost, this sheathing can be offered as an upgrade to the home buyer with an attractive analysis of return on investment. An ancillary benefit to the builder is the ability to include more window area in a given home. The energy benefits of radiant barrier sheathing will allow the builder to meet the State of California Title 24 requirements with greater window area in the home, increasing the homes appeal, value and salability.
All these advantages come at a price that is lower overall than site-built solutions. Energy efficiency and a cost advantage to the builder as well as to the homeowner - what's not to like? Increased profits and greater energy savings, doing well while doing good.
February 2007 Builder Architect Edition Issue