PASSIVE HAUS

Regarded as the most stringent global energy efficiency standard, Passive House has been shown to deeply reduce the carbon intensity of buildings in every climate. The standard has been developed as a performance-based protocol, which informs the design process of a building from its earliest stages of design development to occupancy. The result is a energy savings of 80-90% for heating and cooling, as well as a significantly more comfortable living environment.

Passive House or Passivhaus (meaning “passive building” in German) is a certified building system developed in Darmstadt, Germany and administered by the Passive House Institute. The PHI actively develops building science methodologies and testing to quantify and verify the performance of buildings in all climate conditions and programs. Passive House (PH) differs from passive solar in a number of ways. Primarily, PH utilizes detailed accounts of energy loss and gain in every season, resulting in the ability to design for specific conditions in a given climate, rather than relying solely on solar exposure and glazing placement. 

The most important design motivator for a PH structure is to achieve low annual energy consumption. In order to predict energy usage, an essential tool for every PH designer is the PHPP (Passive House Planning Package) modeling software, which parametrically provides feedback to optimize design decisions. The goal of PHPP is to help the designer meet the stringent energy targets of 4.75 kBTU per square foot a year for heating and cooling, 38 kBTU per square foot a year for total primary energy usage, and a number of other criteria.

The standard focuses on two interdependent goals. Energy reduction is achieved through a fabric-first approach utilizing high performance windows and doors, increased insulation levels, air tightness, reduced thermal bridging, and reduced envelope penetrations. These elements are synthesized with program, budget, and aesthetic values to provide the core of a passive house design process. A balanced energy load accounts for all heat gains and losses in the building on an annual and peak basis resulting in a small amount of energy required to maintain a comfortable environment.

Occupant comfort is achieved though stable indoor air temperatures, especially near windows, and a nearly silent fresh air system that eliminates stale air and improves overall indoor air quality. The high performance building envelope greatly reduces outdoor noise but still allows flexibility for occupants to open and close windows whenever they want. The effect is an optimal level of well-being throughout the year, unmatched by any other building system. 

A robust interface with the building’s surroundings also results in a host of benefits—including durability, resiliency to heat waves and cold snaps, and predictably even when used outside of the scope of the original design intentions. Due to their inherently low annual energy consumption, these buildings are also well suited to achieve zero net energy goals with minimal renewable energy infrastructure.