Proof of concept first was the construction in 1991 of the first Passivhaus project built in Kranichstein, Darmstadt. This multi-family residence was designed and built employing each of the five tenets described above.
Direct southern exposure maximized desired heat gains in primary living spaces; it was detailed using 10 to 18 inches (250-450 millimeters) of polystyrene and blown-in mineral wool insulation for the basement, roof and exterior walls; the windows were triple-pane krypton-filled insulated frames; and air-to-air heat recovery ventilators were used with 80 percent efficiency.
The fresh air intake for each home was located on the northern face of the building with the air ducted below ground for preheating before traveling to the heat exchanger. The housing complex included an unconditioned north-facing glass atrium that performed as a thermal buffer.
Once completed, extensive monitoring began with results confirming the merit of the idea and the attainability of its goals. As published by the Institut, the inaugural Passivhaus uses 88 percent less energy than a typical German home.
The 2007 version of the PHPP is a sophisticated software package available for both residential and non-residential buildings, for new construction and renovations. Validated against 300 projects, the tool facilitates calculation of thermal conductivity values, internal heat gains, energy balance, ventilation rates, total energy demands, and electricity demands from fans and other plug-in loads.
It can be used during the design process to parametrically model the effect of external walls, windows, ventilation rates, solar absorption of external materials, and internal loads on energy use.
Tens of thousands of buildings have already been built using the standard, mostly in Central Europe where the climate is optimal. Yet many of its tenets are just as effective in cooling-dominated environments that depend on air conditioning for thermal comfort.
Highly insulated building skins, minimized thermal bridging, air tightness and energy recovery ventilators are necessary for minimizing the consumption of energy in hot and humid climates. And where abundant solar radiation can be found, the Institut promotes the use of low-tech solar hot water collectors to further offset energy consumption.
These chapters offer access to a wide array of services including certification of consultants and buildings, thermal modeling, and the testing and monitoring of homes and equipment.
The certification process endorses designer/consultants and building inspector/certifiers involved in the delivery of buildings, as well as actual building components tested for performance, including wall and construction systems, glazing, doors, and curtain-wall systems. Certified designers can be found in over 35 different countries including Latvia, United Arab Emirates and Bulgaria.
In the United States, nearly 200 PHIUS consultants help with the decision-making process during the early design phase of a project, during construction as well as during post-construction monitoring. Consultants verify homes to ensure they are built air tight and without thermal bridging; details necessary for achieving the Passive House Building Energy Standard and for securing official certification.
Located in Camden, the two-bedroom, two-storey home is 118 square meters (1,270 square feet) and, in keeping with Passivhaus standards, built using a heavily insulated exterior envelope made of 3-meter-tall retaining walls and prefabricated timber frames.
It features glazed openings to the south for maximizing winter solar heat gains, and it is cool in the summer and warm in the winter.
The PHPP software was employed in siting the house and in establishing the amount and location of fenestration. Triple-glazed windows were used alongside automatic retractable shades for protecting against summer solar exposure. It employs a highly efficient energy recovery ventilator (ERV) that contributes directly to the home's 90 percent reduction in energy consumption over a typical London residence.
In desiring to implement larger ecological strategies, rainwater is harvested and a solar thermal panel is used for supplying the house's domestic hot water needs. Urban landscaping strategies include a green roof and south-facing green wall.
And as noted by bere:architects, the project surpasses the minimum standards of the UK Building Regulations Part L 2006 by 70 percent as well as being compliant with the UK 2016 definition for zero-carbon homes.
The firm's commitment to the Passivhaus program continues, having completed a 6-Month Post-Construction and Initial Occupation Study, and having initiated a 24-Month In-Use Performance and Post-Occupancy Evaluation, both of which were funded by the UK's Technology Strategy Board.
In autumn 2009, the very first Japanese certified Passivhaus was built in Kamakura city, Kanagawa prefecture, Japan, by KEY Architects.
The two-storey home was designed to integrate within its setting as well as to promote the tenets of energy-efficient design.
To this end, it was clad with locally sourced cedar, detailed with an abundance of insulation, glazed with triple-pane windows from Germany and built according to the best practices for achieving air tightness. Light wood-frame techniques were used for the house's main structure and wood fibers were used for insulation.
Its particular invention lay in updating Passivhaus standards for the Japanese climate, being a great deal more humid than the temperate climate of Europe.
Unconventionally, this house used a vapor barrier/retarder that allows the air moisture to travel in both directions across the wall, avoiding the very real possibility of condensation in the building envelope. In so doing, this Passivhaus demonstrates the program's capacity to accommodate to local conditions.
The four-bedroom, 311-square-meter (3,350-square-foot) house was designed to take advantage of passive solar heating for free winter heating. Its compact building volume minimizes heat loss to the exterior, as do the insulated windows and integrated shading.
The building's cross-section clearly identifies the house as designed according to the principles of Passivhaus. The southern exposure is carefully profiled for solar heat gain during the winter season while the northern facade, roof and basement perimeter walls are highly insulated (400-600 millimeters) and barely fenestrated.
The floors to the south of the house are designed for maximizing the benefits of thermal mass. And the house is host to three forms of renewable energy technology including a ground-heat exchanger, photovoltaic solar electric power and solar hot water collectors.
Villa Alstrup has passed post-construction inspections and is in the process of being Passivhaus certified.
Passive House Worldwide
These, and other such projects demonstrate the design potential of adopting Passivhaus standards, be they in Japan, Denmark or the UK; with certification primarily a function of the compactness of the building's volume and the detailing of its skin.
The construction of the roof, exterior walls, and foundations directly impact the home's energy equation. Their materials, detailing and craftsmanship affect the efficacy of the overall standard.
Said otherwise, maximum insulation and minimal air leakage are of greatest value when building a Passivhaus. Recommended operable openings are limited to those used for controlled ventilation, such as the air intake used to transport limited amounts of outside air to the heat exchanger.
These principles, however, may tend to inadequately address the human desire for operable windows, privilege the use of highly engineered insulation materials for the building's exterior finish (to minimize thermal bridging), and limit the amount of fenestration permissible on facades other than the south.
Passivhaus is currently in a class by itself with regard to proven energy performance.
Nonetheless, there are limitations of the system. To extend the portfolio of building options capable of meeting stringent, "2050 proof" performance standards, there is an ongoing need for additional and extended solutions, which will for instance allow increased operability of the building envelope, and more flexible deployment of light transmission.
Franca Trubiano is a Registered Architect (O.A.Q., Int. Assoc. AIA) and is an Assistant Professor at Penn Design, University of Pennsylvania where she also received her doctoral degree. She conducts research in construction technology, emerging materials, tectonic theory, integrated design, and architectural ecologies.