Designers tune the thermal characteristics of buildings so that they moderate external environmental conditions and maintain internal conditions using the minimum resources of materials and fuel.
Passive design maximises the use of 'natural' sources of heating, cooling and ventilation to create comfortable conditions inside buildings. It harness environmental conditions such as solar radiation, cool night air and air pressure differences to drive the internal environment. Passive measures do not involve mechanical or electrical systems.
This is as opposed to 'active' design which makes use of active building services systems to create comfortable conditions, such as boilers and chillers, mechanical ventilation, electric lighting, and so on. Buildings will generally include both active and passive measures.
Hybrid systems use active systems to assist passive measures, for example; heat recovery ventilation, solar thermal systems, ground source heat pumps, and so on. Very broadly, where it is possible to do so, designers will aim to maximise the potential of passive measures, before introducing hybrid systems or active systems. This can reduce capital costs and should reduce the energy consumed by the building.
However, whilst passive design should create buildings that consume less energy, they do not always produce buildings that might be considered 'sustainable' as sustainability is dependent on a range of criteria, only one of which is energy usage.
Passive design can include:
NB: Passive solar design is an aspect of passive building design that focusses on maximising the use of heat energy from solar radiation.
Passive design can include consideration of:
In its simplest form, a shallow building orientated perpendicular to the prevailing wind with openings on both sides, will allow sunlight to penetrate into the middle of the building and will enable cross ventilation. This should reduce the need for artificial lighting and may mean that cooling systems and mechanical ventilation are not necessary. In taller buildings, stack ventilation can be used to draw fresh air through a building, and in deeper buildings atriums or courtyards can be introduced to allow light into the centre of the floor plan.
However, difficulties arise, for example; when buildings have cellular spaces that block the passage of solar radiation and air, or where site constraints create complex massing or mean that windows cannot be opened because of noise or air quality issues. This can lead to the introduction of more complex passive measures, such as trombe walls, solar chimneys (or thermal chimneys), solar stacks, acoustic louvres, thermal labyrinths, and so on.
The situation is complicated further by different climates, changing seasons, and the transition from day to night, so that passive design may have to allow different modes of operation, sometimes rejecting external inputs and expelling the build up of internal conditions, whilst at other times, capturing external inputs and retaining internal conditions.
Typically, these variations can be dealt with through measures such as shading, shutters, overhangs and louvres that allow low-level winter sun to penetrate into the building, but block the higher summer sun. Thermal mass can be used to store peak conditions during the day and then to vent them to the outside at night. Even deciduous trees can be beneficial, their leaves shading buildings from summer sun, but then allowing the solar radiation to penetrate through their bare branches during the winter.
Additional complexities can be introduced by internal heat loads such as people and ICT equipment and by occupancy patterns. In a 9-to-5 office with a moderate amount of installed equipment, it may be possible to use thermal mass to store heat loads during the day and then to vent these and cool the thermal mass when the building is unoccupied at night. This may not be possible with a building such as a hospital that is continuously occupied.
Considering all these issues early in the design process, so that they can be incorporated into the fundamental design of the building, requires close working across the entire design team. The historic model, where the architect designed a building and then a structural engineer made it stand up and then last of all a services engineer made it comfortable, is unlikely to achieve a satisfactory result.
Passive design measures can require occupant involvement, for example to open windows, turn out lights, adjust louvres, and so on. This requires education so that occupants are able to understand the building and to operate it efficiently. Occupant behaviour is often cited as one of the prime causes of the 'performance gap', that is, the difference between the expected and actual energy consumption of completed buildings.
As well as reducing energy consumption, adopting passive design strategies can help building ratings across standards such as PassivHaus, BREEAM, the Code for Sustainable Homes and LEED.
NB: The urban heat island effect, is an effect found in urban environments where the predominance of hard, heat absorbing surfaces results in a higher ambient temperature than in rural environments. It has been found that simply selecting lighter coloured materials that reflect solar radiation rather than absorbing it can significantly reduce urban temperatures and so the need for active systems to provide cooling.
FAQs
'Passive design' is design that works with the local climate to maintain a comfortable temperature in the home. Good passive design should reduce or eliminate the need for additional heating or cooling depending on your location and often relies on an active occupant to work properly.
What is passive design in buildings? ›
'Passive design' is design that works with the local climate to maintain a comfortable temperature in the home. Good passive design should reduce or eliminate the need for additional heating or cooling depending on your location and often relies on an active occupant to work properly.
What are the 5 passive house principles? ›
Fundamental to the energy efficiency of these buildings, the following five principles are central to Passive House design and construction: 1) superinsulated envelopes, 2) airtight construction, 3) high-performance glazing, 4) thermal-bridge-free detailing, and 5) heat recovery ventilation.
What is an example of a passive building? ›
Examples of passive design include optimising spatial planning and orientation to control solar gains and maximise daylighting, manipulating the building form and fabric to facilitate natural ventilation strategies and making effective use of thermal mass to help reduce peak internal temperatures. '
What are the disadvantages of a passive house? ›
Pros and Cons of Passive Houses: Are They Worth It?
- Expensive Construction.
- Special Maintenance Knowledge Required.
- Passive Homes Don't Fit in Every Location.
- Internal Noise Concerns.
- Remodeling an Old Home Into a Passive Home Is Expensive.
- Passive Homes Must Meet Standards.
Passive design strategies use ambient energy sources instead of purchased energy like electricity or natural gas. These strategies include daylighting, natural ventilation, and solar energy. Active design strategies use purchased energy to keep the building comfortable.
Are passive houses more expensive to build? ›
Passive Design Solutions is designing homes that can be constructed at the same cost as a code-built home with equivalent square footage in many markets. The cost increase for building envelope upgrades ranges from 5% to 10% of the total construction budget for a single-family home.
What are the walls in a Passive House? ›
The typical passive house will have very thick walls and roofs, a fairly simple shape, and high performance windows and doors. Typical walls might be 12" to 24" thick (R35 to R60) and roofs might be 18" to 36" thick (R50 to R100).
What windows are used in a Passive House? ›
Passive house windows use either triple glazing or super-efficient double glazing. The glass and materials used to make the frames must have low thermal conductivity. Specially coated glass is used, and the cavity between the glass is filled with a gas with low conductivity such as argon.
What is the R value of a Passive House? ›
The Passive House recommended standard is </ 0.8 W/m2/K (</ 0.14 Btu/hr-sf-F) equivalent to an R-7. To achieve this performance, windows are constructed with nonconductive frame materials such as wood or fiberglass and with triple-pane, gas-filled lites.
These are just a handful of passive design strategies in action.
- Emphasize Cross Ventilation. ...
- Keep Spaces Open. ...
- Rethink Mechanical Design. ...
- Control Heat. ...
- Have Optimal Insulation. ...
- Use High-Performance Windows and Doors. ...
- Have Proper Solar Orientation. ...
- Design an Airtight Envelope.
The Passive House criteria allow buildings to go by either criterion - the 15 kWh/(m²yr) heat demand OR the 10W/m² heating load. The minimum fresh air flow rate for one person is 30 m3/h (according to the DIN 1946 – health criterion). At 21°C and standard pressure, air has a heat capacity of 0.33 Wh/(m3K).
What materials are used in a Passive House? ›
What Materials Are Used In A Passive House?
- Bio-based spray foam insulation.
- Closed panel timber frames for doors and windows.
- Engineered and recycled lumber.
- Environmentally-friendly paint types with low VOC.
- Fluorescent light bulbs.
- Formaldehyde-free cabinets.
- Insulated concrete forms for foundations.
A Passive House is designed to be highly-insulated and air-tight, and is primarily heated by passive solar gain and internal gains from people and equipment. Energy losses are minimal. The window U-value recommendation for a Passive House is ≤0.8 W/m2/K (≤0.14 Btu/hr-sf-°F).
What do you need for a Passive House? ›
Passive homes need to be air-tight, have continuous insulation, triple-paned windows, and a great system for controlling air quality.
Can you open windows in passive house? ›
Can you open windows in a Passive House? Passive House occupants may open windows whenever they want. The beauty of Passive House design, however, is that they won't have to.
Do passive houses need ventilation? ›
Therefore, a Passive House requires ventilation systems with a heat recovery efficiency of at least 75% and power consumption should not exceed 0.45Wh/m³ of the transport air volume. Moreover, the acoustic load of the ventilation systems should not exceed 25dB in living rooms and 35dB in the ventilation system room.
Does passive house need AC? ›
Even though a Passive House is designed to not need a traditional heating and cooling system, a ductless heat pump can serve as the perfect accessory for any energy-efficient and ecologically conscious home. This is because a Passive House building and a ductless heat pump share many of the same design principles.
What is the advantage of passive building system? ›
The design of passive houses allows them to be highly energy efficient. In fact, passive houses have the potential to use up to 90% less energy than the current building stock while still performing the same functions as traditional buildings. Sometimes even, passive houses can perform way better.
What is the opposite to a Passive House? ›
Active House is basically an evolution of Passive House that goes one step further than a zero carbon footprint, by encouraging homes to produce positive energy which can then be fed back to the grid, often via photovoltaic panels.
'Passive House' is a design standard that achieves thermal comfort with minimal heating and cooling by using insulation, airtightness, appropriate window and door design, ventilation systems with heat recovery, and elimination of thermal bridges.
What is the best roof for Passive House? ›
The Passive House Institutes Certification represents the highest energy efficiency rank for residential homes. Metal roofing is seen as the ideal option for those looking to achieve a net-zero energy emittance, thanks to the material's ability to reflect solar and thermal energy.
Can you turn a normal house into a Passive House? ›
By slowly renovating your older home to move towards the passive house standards, you can save money, reduce carbon emissions, and increase your home's comfort and value. At the same time, you'll also avoid the high embodied energy cost of building a new home!
What is the most efficient style of house to build? ›
Like geodesic dome homes, tiny homes are more energy efficient than other builds because they have less surface area. However, tiny homes are more efficient because they are smaller overall while geodesic dome houses are efficient because of their particular shape.
What is the best wall construction for Passive House? ›
Insulated concrete form (ICF) construction provides the best solution to passive house design because they create air-tight walls with continuous insulation (CI), moisture resistance, and high thermal mass — vital components of a passive house design.
How thick are exterior walls in a Passive House? ›
The walls of a passive home are at a minimum of 6-inches thick, and in some places, may go to as much as 12-inches thick to accommodate additional insulation.
How are passive houses insulated? ›
A continuous layer of insulation wraps Passive House buildings, keeping them warm in the winter and cool in the summer. Passive House designers also harness this insulative layer to prevent condensation inside the building and its assemblies.
How does a Passive House get fresh air? ›
The ventilation systems used in Passive Houses provide unparalleled indoor air quality through the use of a high quality, F7 filter at the suction point (the unit must also be equipped with a drain). During heat recovery, the exhaust air must not mix with the supply air.
Are passive houses worth it? ›
Because passive houses are so efficient, it's easy to maintain a comfortable indoor temperature no matter the season. Savings on heating and cooling costs can be as high as 90% compared to conventionally built homes, since passive buildings use just 15 kWh of heating energy per 10 square feet per year.
What insulation is best for passive homes? ›
Materials such as wood fibre insulation or Porotherm blocks (perforated clay blocks) have high mass, high specific heat capacity and store large quantities of heat. Standard masonry also works well although it does release heat rather quicker and so less effective at storing heat.
A Passive House requires as little as 10 percent of the energy used by typical central European buildings – meaning an energy savings of up to 90 percent!
How much insulation is needed for passive house? ›
For a passive house, the U-values should be as low as possible, typically between 0.10 and 0.15 W/m²K.
Do passive houses stay cool in summer? ›
Passive House buildings are designed to be comfortable all year round – cozy and warm in winter (20°C), comfortably cool in summer (25°C).
Do we need underfloor heating in passive house? ›
Floor heating systems are a great choice for passive house projects, bringing radiant warmth to every room of your home. Using a Warmup underfloor heating system alongside a renewable heat source can also improve the energy performance of your home and provide you with significant energy savings.
How much air can a passive house change in an hour? ›
Very low air leakage rates are required by the Passivhaus standard and must be demonstrated for each certified building by means of a “blower door” air tightness test. The air change rate must be less than or equal to 0.6 air changes per hour, under test conditions.
Do passive houses get dusty? ›
Passive houses are airtight, with a ventilation system that filters out pollen and allergens more quickly due to its efficiency. As a result, it also lets in far less dust as well, keeping the air fresh and free of pollutants and odors that may irritate those with allergies.
Do passive houses need solar panels? ›
Passive homes are heated primarily by the sun, but unlike solar-powered houses, which use solar panels to convert sunlight to electricity, passive houses capture the sun's energy in the form of heat, using the design and construction of the home itself to eliminate the need for a furnace, fireplace or other ...
What is the largest passive house? ›
The largest building in the world to meet the Passive House Institute standards for energy efficiency, comfort and affordability is the 270,000 ft2 (25,084 m2) Cornell Tech's House residential tower in New York, USA.
What is the thermal comfort for a passive house? ›
Passive Houses are buildings that need very little energy to achieve a comfortable temperature without the help of either a conventional heating or air conditioning system.
What is the first thing to consider when designing a passive house? ›
The main things to focus on when deciding the performance of the building fabric will be determined by the type of insulation used, the thermal performance of this insulation (also known as the lambda value), the U-value for the components and any potential thermal bridging where these components intersect.
A passive solar house should be constructed on the south-facing slope of a mountain to avoid the extreme shading created where the low-angled sun is blocked by the mountain on the north side.
What are the advantages of passive architecture? ›
Passive house design strives to maintain a comfortable, even temperature throughout the home, with low temperature variations from room to room. The difference between radiant temperature (i.e., the temperature of windows, doors and other surfaces) and air temperature remains small, helping to eliminate drafts.
What is passive space in architecture? ›
Passive Architecture describes buildings that are designed to cope with the climate factors by providing comfortable indoor conditions enduringly and naturally [18], [19].
What are the design features of a passive house? ›
The five principles of passive house design
- No thermal bridging.
- Superior windows.
- Mechanical ventilation with heat recovery.
- Quality insulation.
- Airtight construction.
Can you open windows in a Passive House? Passive House occupants may open windows whenever they want. The beauty of Passive House design, however, is that they won't have to.
What is the difference between a Passive House and a LEED? ›
Both LEED and Passive House have criteria that involve user health and comfort. LEED covers materials and fixture selection while Passive House focuses on providing filtered fresh ventilation to every space. Also, meeting the Passive House thermal comfort criteria are fundamental aspects of certification.
What is the purpose of a Passive House? ›
Passive house (German: Passivhaus) is a voluntary standard for energy efficiency in a building, which reduces the building's ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling.
