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Executive Summary
This report summarizes an examination of specific building performance issues in Minnesota homes built during a time of transition in building practices and energy code changes. It intends to evaluate the role these transitions play in improving housing to be more durable, safer, and energy efficient. This project was undertaken to evaluate and compare homeowner perceptions and the effectiveness of building envelope changes, combustion safety upgrades, and mechanical ventilation systems in homes built in 1994, 1998, a nd 2000.
A sample of 43 homes received performance testing and visual inspections. The homeowners were interviewed regarding energy use, comfort issues, indoor air quality, and mechanical system operation and maintenance. Utility usage was monitored and analyzed to quantify energy savings resulting from efficiency upgrades. This study foun d that:
， Homes built under the Chapter 7672 and Category 1 codes are more tightly constructed than those built to Category 2 requirements by an average of 29%. ， The average 1998 home in this sample uses 21% less energy to heat than the average 19 94 home.
， The average 2000 home in this sample uses 25% less energy to heat than theaverage 1994 home and 5% less than the average 1998 home.
， Mechanical ventilation systems of this sample set are meeting or exceeding theminimum airflow requirements of the new energy codes.
， Despite being less airtight, Category 2 homes in this sample are more susceptibleto combustion safety issues than Category 1 and Chapter 7672 homes.
， Homeowners want and need more information and guidance regarding theoperation and maintenance of their mechanical ventilation systems and how theyaffect the performance of their home.
， Incremental increased costs associated with energy code compliance amount toapproximately 1-2% of the cost of the home.
， Savings in heating and cooling costs offset the additional expense for energyupgrades to comply with the energy code in most homes reviewed.While this sample set is small and of limited use as a statistical predictor, the informationcollected provides valuable insight as to how some new homes are performing and as to
what issues need further attention. Energy code requirements alone do not guarantee
home performance, ensure indoor air quality, or improve attention to detail by builders
and subcontractors. The building industry has a goal of providing homes that are safer,
healthier, more energy efficient and offer better durability while providing affordability
in owning, operating, and maintaining homes. With this in mind, builders and consumers
are learning to understand the complexity of improving building performance. This
creates a need for ongoing training for all facets of the homebuilding industry including
building officials, subcontractors, manufacturers, and consumers. | 