Passive House Design: How It Works and Misconceptions Explained
Do you dream of an off-the-grid life? Are you traumatized by utility bills? Are you in despair over climate change and wondering what you can do to save the earth? If so, building a passive house may well be in your future. Passive houses optimize the most innovative and up-to-the minute construction technologies to lower owners’ utility bills by ninety percent—or even more.
The secrets of a passive house are a versatile wall system that seals the house, admitting no unwanted cold or heat; triple paned windows that further insulate the house; window placement that accounts for cold winds and makes use of the sun’s power; and an energy exchange system that recycles heat from the kitchen and shower while an underground reservoir cools or warms the home’s air to keep it temperate year round.
Advantages of a Passive House
The advantages of building and owning a passive house are numerous. These are the high points:
- Energy efficiency and savings — Thick walls, superior insulation, and clever use of passive solar power come together to substantially lower heating and air conditioning bills. Industry leaders estimate that passive homes save their owners an average of ninety percent on their utility bills. Some passive homes even achieve the green design gold standard: donating energy back to the grid while the homeowner pays no utility bills whatsoever.
- Individualism — The principles of passive house building can be achieved in many different ways and with many different designs and materials. That means that passive houses can be tailored to the tastes and lifestyle of the owner. When you build passive, you may well be building a home that doesn’t look like anyone else’s. Want three bedrooms and four bathrooms? No problem. Want your house to look like it belonged to the Bronte sisters? Passive home modelers can do it. The flexibility of design and house exterior options also mean that you can build a passive house that is respectful to the architectural idiom of the neighborhood. Passive houses need not stick out like sore thumbs or offend the neighbors.
- Environment-friendly — Building an energy efficient home is always the right thing to do—for the planet and your grandchildren. Passive house designs gives you a flexible way to build a green home.
Disadvantages of a Passive House
There are far more advantages than disadvantages to building a passive house. However, homeowners and builders will want to carefully weigh the costs against the likely future value of the home.
The main disadvantage to building a passive house is the upfront cost. Industry leaders generally agree that the cost of building a passive house is ten percent higher than building a house that simply meets local code requirements. However, it should be noted that one building consultant, Tim McDonald, claims to have brainstormed a passive design, multi-family structure for the cost of a conventional structure. McDonald credits the prefabricated wall system for the building’s low cost.
Another broad disadvantage to passive design is that it can be implemented to optimal standards only in new construction. A home remodel can certainly take advantage of some aspects of the passive standard, most notably triple paned window replacements and high efficiency insulation. However, the elaborate exhaust system and heat exchange technology of a newly constructed passive house is likely to be cost prohibitive for most remodelers.
Another consideration is whether a well-built passive house will retain its value. Energy efficiency is still a low priority for the majority of homebuyers, especially in the under $400,000 range. While there is certainly an argument for educating homebuyers about the virtues of energy responsibility, builders will want to carefully consider which neighborhoods will value a virtually net zero home and which will not.
There are two factors to consider: political bias and local property values. Politically progressive cities and neighborhoods like San Francisco, California and Austin, Texas are fertile ground for passive houses. In such cities and neighborhoods, where many people value environmental conservation and believe in the science of climate change, a passive house is likely to be a good investment. In archly conservative regions, such as eastern Kentucky and rural South Carolina, homebuyers may react with indifference or even contempt to a house that is built to protect the planet’s resources.
The other factor to consider is the value of houses in the neighborhood where the passive house is projected for construction. A passive house is likely to retain or improve its value in an upscale neighborhood where the average home costs $300,000 or more. A neighborhood where home prices are well under $200,000 or where there is a high percentage of foreclosures is, at best, a risky place to build a passive house.
The builder should be aware that, in many neighborhoods across the United States, the home could end up being worth less than the construction costs. If the homeowner/builder is constructing a retirement home or plans to live in a passive home for the rest of his life, then it may not matter whether it increases in value. For the purposes of investment, however, if there has been no new construction or major remodeling in the neighborhood for a year or more, a passive house will not be a good investment.
Common Misconceptions About a Passive House Design
It is important to differentiate between the few and true disadvantages to building a passive house and the common misconceptions, many of them held by veteran builders who ought to know better.
One of the most common beliefs about passive homes is that they are necessarily ugly. Admittedly, this belief is based on earlier energy-efficient home designs such as the earth home which was typically constructed of unpainted cement blocks. Green design has a long and illustrious past of unattractive materials, but that is simply no longer the case. For years, green designers have paid careful attention to the attractiveness of their houses and to homeowner comfort and the ability to utilize every square inch of the home.
One tremendous advantage of passive homes is that they require no particular materials. If you like cement, you can build with that. If you prefer a house with the warmth of natural wood cladding, you can incorporate that material into the design. Basically, you can design a passive house exterior that’s as futuristic as Blade Runner or as traditional as a nineteenth-century Vermont farmhouse.
Another misconception about passive houses is that the walls take up a substantial amount of space that could otherwise be used by the inhabitants. It is true that passive design walls are roughly six inches thicker than most walls that are built to minimum code standards. However, most homes have hot and cold spots that make parts of the house effectively unusable.
A Florida room with a bank of windows may be too cold in the winter and too hot in the summer. Conventional homeowners often resort to light and window obscuring thermal draperies that darken the home and make it much less a pleasure to live in. Passive houses, by contrast, are designed to be the same temperature throughout. That means that owners can enjoy the winter sun and scenery out their windows just as much as the spring and fall scenery.
Passive House: An Inevitable Trend
Tree huggers will always want homes with a low ecological footprint, but green design has evolved to also benefit off-the-gridders. Everyone wants low utility bills and a comfortable home. Passive house design promises to deliver all that and more.