building science


PATH is an acronym for the building science principles that govern the way we build.

Pressures of water vapor

High water vapor concentration moves to low water vapor concentration. You can think of this as humidity equalizing in an enclosed area. Moisture levels vary greatly between different areas in a home. During certain times of the year water vapor pressures are very different between inside and outside your home. The pressures exerted by water vapor are very strong. Humidity will equalize even faster than heat.

Air pressures

Air pressures move from high pressure to low pressure. Pressure is affected by wind outside and fans, chimneys, and vents on the inside. Convection creates low pressures on the lower levels and high pressures on the upper levels of a home or building. This is called the chimney effect and can result in heat loss as well as differing temperatures on different levels.

Temperature of dew points

Dew Point is the temperature at which water vapor will change into liquid water. This is both a function of temperature and the amount of moisture in the air. The concern in most structures is allowing too much humid air into the wall or roof assembly so that when the moisture in the air condenses, it overwhelms the drying ability of the building materials, leading to mold and possibly structural damage.

Heat flow

Heat moves from areas of higher temperature to areas of the home with lower temperatures. While heating the home, heat is escaping through conduction, convection, and radiation. The opposite is true while cooling the home. Heat is flowing toward the lower temperature area of the inside. Insulation is designed to resist the heat flow process. The higher the R-value in the insulation, the slower the heat flow process. Heat is also lost through air movement and insulation cannot be effective if there is air movement through it.

Thermodynamics is the field of physics that deals with the relationship between heat and other properties, such as pressure and heat transfer. Our concern is how moisture and air move through wall assemblies. 


FORWARD  is an acronym that defines our priorities and goals when developing and building a project.

Focus on energy efficiency

An eco house by Morrissey Builders can save fossil fuels, reduce carbon dioxide pollution, and reduce energy bills through proper installation of windows and doors, air sealing, innovative wall systems, efficient lights, natural day lighting and energy efficient electrical appliances and heating equipment. Careful siting of renewable technology such as solar thermal and photovoltaic equipment can also be economically justified if conservation measures have been applied extensively.

0peration interface

An eco house creates a healthy living environment by working collaboratively with owners. From rain gardens to solar panels to grey-water systems, an eco house introduces new concepts which an owner must understand and maintain. Morr Construction helps the home owner learn these new systems. A Morrissey Builders eco house is also third-party inspected by MN GreenStar, tested and certified to be higher performing than conventional homes. Homes are healthier and more comfortable.

Regional resources

Morrissey Builders also considers the greater community when building an eco house. Morrissey Builders sources local vendors for locally produced materials to find products within 500 miles of a site; minimizing shipping, employing local workers, and benefiting the local economy. Less transport means less energy use and harm to the environment and less embodied energy in using local products.

Water conservation

When designing and building an eco house, Morrissey Builders strives to conserve water though the purchase and installation of low-flow shower heads, aerators for faucets, low-flow and dual-flush toilets, and water-friendly clothes washers. Grey-water recycling can greatly reduce a home’s water consumption by using waste water from sinks to flush toilets. Exterior water saving techniques include installing cisterns for catching rainwater, drainable pavers, and landscaping that does not need irrigation. Clean water will continue to be a major concern for all.

Air quality and health

Morrissey Builders improves indoor air quality, which benefits health, by choosing eco-friendly products. Off-gassing of products, from carpets, paints, and varnishes, can impact health. Eco-friendly products with fewer toxins are chosen. Whole house ventilation and point-of-use powered vents are installed, where needed, to reduce humidity, cooking exhaust, and indoor air pollution. The HVAC system is designed for the way you live.

Resource protection

Morrissey Builders takes deliberate actions to reduce waste, saving money and the environment. Use of Atomic Recycling bins diverts an average of 70% of waste away from landfills. Materials are chosen by recycled content, low volatile organic compounds, and durability. A deliberate effort is made to reduce material waste through careful estimating; returning overages quickly.

Design and durability

At Morrissey Builders, our philosophy is “Building for the Future Today.” Within the construction industry, this can be referred to as ‘sustainable design.’ Sustainable design is about environmental equilibrium - balancing human needs for durable homes with nature’s ability to replenish herself. To be executed properly, sustainable design encompasses the seven core principles (FORWARD). The principles can also be grouped as five components:

1) environment;
2) exterior envelope;
3) mechanical systems;
4) interiors; and
5) occupants.