Passive construction follows a voluntary standard for ultra-low energy buildings. Intended for both residential and commercial construction, the passive building movement is becoming more popular every year. The world now has thousands of passive homes, several passive office buildings, passive schools, and even a passive supermarket.
The passive construction approach creates extremely energy efficient, basically airtight structures. As Oregon demolition experts, we closely follow construction trends, including passive construction. We must understand how today’s buildings are constructed, so that we can optimize demolition going forward. If you, like most Americans, are unfamiliar with how passive construction works, you will find the following list of basic facts useful.
Portland Demolition Experts’ Top 5 Facts to Know about Passive Construction
- Passive construction greatly reduces a building’s ecological footprint.
According to the PassivHaus standards, a passive structure’s annual heating and cooling demand must be less than 15 kWh/m2 OR a peak heat load of 10W/m2. Additionally, the structure’s total primary energy consumption (for heating, hot water and electricity) must be less than 120 kWh/m2 per year. In general, a passive house will use 75-95% less heating and cooling energy than required for typical US buildings. The PassivHaus Institute defines a passive structure as one that is so energy efficient that no active heating or cooling system is needed. (However, passive structures may include an active heating/cooling component, often a heat pump within the exhaust system, to mollify skeptical clients.) A passive structure’s ecological footprint is further minimized via energy efficient appliances and alternative energy sources, such as solar arrays and wind turbines.
- Most passive structures are in German-speaking countries and Scandinavia.
As of August 2010, there were 25,000 certified Passivhaus buildings in Europe, and only 13 in the US. The co-creators of the passive building movement, Bo Adamson and Wolfgang Feist, are from Sweden and Germany, respectively. The passive building concept sprung from a conversation these two innovators had in May 1988. After numerous research projects funded by the German state of Hessen, the first passive homes were built in 1990. The Passivhaus-Institut was founded in 1996 to promote and control the Passivhaus standards.
- Passive construction includes passive solar building design.
Passive homes use the power of the sun, but in a different way than solar panels. Instead of converting sunlight to electricity, passive buildings are created to capture heat from sunlight. Each passive structure is designed to retain solar heat to such a high degree that no other heating element is needed. Extended window shields may be positioned to allow as much light and heat in as possible during short winter days, but provide shade and cooling during the summer months. Trellises and trees can be placed to block harsh winter winds and shading the home in the summer.
- Passive structures are super-insulated and virtually free of air leaks.
An infrared image of a traditional structure next to a passive structure would show where heat escapes (in red) and where there is no heat lost (in blue). A passive structure aims to prevent heat loss through exceptional insulation, and a remarkably tight building envelope overall. The super-insulation in passive structures may be up to 13 inches thick. Passive construction windows have exceptional R-values, thanks to triple-pane insulating glazing, sealed argon or krypton in between panes, air seals, and specially designed window frames. Bonus: the high quality building methods needed to meet PassivHaus standards translates to less required maintenance over the building’s lifespan.
- Passive structures boast exceptional air quality, thanks to advanced ventilation systems.
Energy-efficient, cutting edge ventilation systems are integral to passive structures. Sophisticated ventilation is required to minimize humidity and keep interior air fresh. Passive buildings’ ventilation systems pull air out of high-moisture rooms (bedrooms, bathrooms) and odor-producing rooms (kitchens, bathrooms) and deliver fresh air to the home’s interior, maintaining humidity at 30% to 60%. While passive structures’ windows may be opened, they may also remain closed to minimize the amount of allergens entering the home. Each ventilation system includes a powerful filter to remove dust and other allergens before air is pumped throughout the system.
Passive construction creates a cozy, quiet indoor environment, in which all of the rooms are the same temperature and super insulation provides noise control.
In 2009, the G8 met to set a lofty goal: reduce global greenhouse gas emissions by 80%. According to the U.S. Energy Information Administration, buildings cause 48% of greenhouse gas emissions. Passive buildings can slash heating/cooling energy requirements and emissions by as much as 95%! As such, we can expect passive construction to become the new standard in the next few years. As Portland building demolition experts, we are excited to watch the passive building movement grow in the years to come.