Richard Pedranti Architect

Passive House

A Passive House is the most stringent building energy standard in the world. Buildings that meet the Passive House standard use 80% less energy than conventional buildings. A Passive House conserves energy by creating a virtually air-tight, super insulated, compact building envelope that uses the sun and internal gains to achieve space conditioning. A heat recovery ventilator (HRV) is used to condition extract air and provide superior indoor air quality. A Passive House can achieve Zero Energy Building (ZEB) building energy standard with the use of a small renewable energy system.

 

Passive House

 

Benefits of a Passive House
Extremely Low Energy Use
Up to 90% less heating/cooling energy use, 60-80% overall energy savings
High Quality Indoor Air
Controlled ventilation for a continuous, consistent supply of filtered fresh air
Comfortable Indoor Temperatures
Buildings are designed to easily maintain a steady, comfortable temperature without irritating temperature swings common in drafty buildings
Operational and Construction Savings
Vastly reduced utility bills; elimination of conventional HVAC system; much smaller alternative energy required, best start to reach a net-zero project; durable, tight building shell reduces maintenance over the life of the building
Proven Sustainability
Certified Passive House Buildings have been constructed in the United States from Minnesota to Louisiana, from Maine to California. Globally, more than 20,000+ buildings have been constructed using Passive House principles, some zero and even net-positive energy buildings. In fact, the standard is so beneficial; many European countries have already or are in process of adopting it in their building codes.
Helping the Earth
With buildings contributing as much 47 percent of all greenhouse gases, Passive Houses are exponentially friendlier to the environment because of their minimal energy and fossil fuel consumption. They also consider the C02 contributions to global warming and embodied energy characteristics of all its selected building materials. You don’t have to wait 18 years; Passive Houses can meet the Architecture2030 challenge, today! “Doing more, with less” to maximize the success of our local and now global communities while simultaneously improving our role as stewards of the earth, is the underlying spirit of the Passive House movement.

 

Design Strategies of a Passive House

“Maximize your gains, minimize your losses”. These are the basic tenants of the Passive House approach. A Passive House project maximizes the energy efficiency of the basic building components inherent in all buildings; roof, walls, windows, floors and the utility systems: electrical, plumbing & mechanical. By minimizing a building's energy losses, the mechanical system is not called to replenish the losses nearly as frequently, saving resources, operational costs and pollution. Unlike any other structures, Passive House buildings maintain occupant comfort for more hours of the year without the need for mechanical temperature conditioning of the indoor air. The opposite has been the norm in this country with a history of inexpensive fuel and construction techniques with little consideration for energy losses through thermal bridging, air-infiltration, let alone being conscious of using some or even any insulation. The Passive House approach focuses on the following:

Strategic Design and Planning
Passive House projects are carefully modeled and evaluated for efficiency at the design stage. Certified Passive House Consultants (CPHC) are trained to use the Passive House Planning Package (PHPP), a tool that allows designers to test “what-if” scenarios before construction begins. They are also trained to use other software tools to identify and address potential thermal bridges and moisture issues at the design stage.
Specific Climate, Siting and Sizing
Passive House design uses detailed, specific annual weather data in modeling a structure’s performance. Orientation of the windows can maximize or minimize solar gain and shading. Passive House theory leans towards minimizing the surface area to interior volume ratio, favoring an efficient shape to minimize energy losses.
Super-Insulated Envelope
To keep the heating/cooling in, wall assemblies require greater insulation values to “stop the conditioned air” from leaving. Walls are typically twice as thick as today’s standard construction, for good reason. Wall assemblies are analyzed to allow for proper water and moisture management to make a long lasting and an exceptionally healthy building.
Thermal Bridge-Free Detailing
Breaks in the insulation layer usually caused by structural elements and utility penetrations in the building envelope create a “thermal bridge,” allowing undesirable exterior temperatures to migrate to and “un-do” expensive interior conditioned air. Passive House design attempts to eliminate thermal bridges via progressive mindful architectural detailing.
Air-Tight Envelope (But Diffusion Open)
Anyone who has been in an older drafty home understands how stopping unconditioned air from squeezing to the inside, effects comfort and the efficiency of the mechanical system. Passive House takes great care in designing, constructing and testing the envelope for an industry-leading control of air leakage to the interior. Blower door testing is a mandatory technique in assuring high performance. Walls are designed to be virtually air tight, while allowing water vapors to dry out providing an excellent strategy to maintain a healthy environment.
Advanced Windows and Doors
Historically these items are the weak link of a building’s envelope and thermal defense system. Passive House places significant emphasis on specifying high performance windows and doors to address concern. To meet the high performance needs of various climate zones, windows must meet strict performance standards regarding: component insulation, air tightness, installation and solar heat gain values.
Energy Recovery Ventilation
The “lungs” of a Passive House come from a box called a heat (or energy) recovery ventilator (HRV/ERV). It provides a constant supply of tempered, filtered fresh air 24/7 and saves money by recycling the indoor energy that is typically found in exhaust air. The heat from outgoing stale air is transferred to the unconditioned incoming fresh air, while it is being filtered. It provides a huge upgrade in indoor air quality and consistent comfort, especially for people sensitive to material off-gassing, allergies and other air-borne irritants.
Heating
One of the best benefits to implementing Passive House design is the high performance shell and extremely low annual energy demand. This allows owners to save on operational costs as they can now significantly downsize a building’s mechanical system. Passive solar gains, plus heat from occupants and appliances supply most of the needed heat. Thus, Passive House design puts a project within reach for achieving true “Net Zero” performance (the building generates as much energy as it consumes over the course of a year), making use of alternative energy systems smaller thus more affordable and attainable.
Efficient Systems
Through fitting buildings designed to the Passive House Standard with efficient appliances, hot water distribution, and energy efficient lighting, electricity consumption is also slashed by 50% compared to the average housing stock, without any loss of convenience. Most Passive House residential ventilation systems, for instance, are typically driven by a highly efficient motor only consuming 40w.
Alternative Energy
Considering alternative energy systems on your project? Building to meet the Passive House Standard is the smartest starting point. The significant reduction in energy use, allows alternative energy to power a greater percentage of a buildings demands. Likewise smaller demand equates to smaller and more affordable alternative energy systems providing higher cost-benefit value. Passive House design puts a project within reach for achieving true “Net Zero” performance (the building generates as much energy as it uses).
© 2011 RICHARD PEDRANTI ARCHITECT | richard@richardpedranti.com