X Международная студенческая научная конференция Студенческий научный форум - 2018

Passive house is a rigorous, voluntary standard for energy efficiency in a building, reducing its ecological footprint. It results in ultra-low energy buildings that require little energy for space heating or cooling. Passive design is not an attachment or supplement to architectural design, but a design process that is integrated with architectural design. Although it is mostly applied to new buildings, it has also been used for refurbishments.

The Passivhaus standard originated from a conversation in May 1988 between Bo Adamson of Lund University, Sweden, and Wolfgang Feist of the Institut für Wohnen und Umwelt (Institute for Housing and the Environment, Germany). Their concept was developed through a number of research projects, aided by financial assistance from the German state of Hessen.

The eventual building of four row houses (terraced houses or town homes) was designed for four private clients by the architectural firm of Bott, Ridder and Westermeyer. The first Passivhaus residences were built in Darmstadt, Germany in 1990, and occupied by the clients the following year.

In September 1996 the Passivhaus-Institut was founded, also in Darmstadt, to promote and control the standards. Since then, thousands of Passivhaus structures have been built, to an estimated 25,000 as of 2010. Most are located in Germany and Austria, with others in various countries worldwide.

After the concept had been validated at Darmstadt, with space heating 90% less than required for a standard new building of the time, the Economical Passive Houses Working Group was created in 1996. This group developed the planning package and initiated the production of the innovative components that had been used, notably the windows and the high-efficiency ventilation systems. Meanwhile, further passive houses were built in Stuttgart (1993), Naumburg, Hesse, Wiesbaden, and Cologne.

The world's first standardised passive prefabricated house was built in Ireland in 2005 by Scandinavian Homes, a Swedish company that has since built more passive houses in England and Poland.

The Passivhaus standard requires that the building fulfills the following requirements:

The building must be designed to have an annual heating and cooling demand as calculated with the Passivhaus Planning Package of not more than 15 kWh/m² per year in heating or cooling energy OR be designed with a peak heat load of 10 W/m².

Total primary energy (source energy for electricity, etc.) consumption (primary energy for heating, hot waterand electricity) must not be more than 60 kWh/m² per year.

The building must not leak more air than 0.6 times the house volume per hour (n₅₀ ≤ 0.6 / hour) at 50 Pa as tested by a blower door, or alternatively when looked at the surface area of the enclosure, the leakage rate must be less than 0.05 cubic feet per minute.

Further, the specific heat load for the heating source at design temperature is recommended, but not required, to be less than 10 W/m².

These standards are much higher than houses built to most normal building codes.

By achieving the Passivhaus standards, qualified buildings are able to dispense with conventional heating systems. While this is an underlying objective of the Passivhaus standard, some type of heating will still be required and most Passivhaus buildings do include a system to provide supplemental space heating.

In Passivhaus buildings, the cost savings from dispensing with the conventional heating system can be used to fund the upgrade of the building envelope and the heat recovery ventilation system. On average passive houses are reported to be more expensive upfront than conventional buildings – 5% to 8% in Germany, 8% to 10% in UK and 5% to 10% in USA.

Achieving the major decrease in heating energy consumption required by the standard involves a shift in approach to building design and construction.

To achieve the standards, a number of techniques and technologies are used in combination.

Passive solar building design and energy-efficient landscaping support the Passive house energy conservation and can integrate them into a neighborhood and environment. Following passive solar building techniques, where possible buildings are compact in shape to reduce their surface area, with principal windows oriented towards the equator - south in the northern hemisphere and north in the southern hemisphere - to maximize passive solar gain.

Passivhaus buildings employ superinsulation to significantly reduce the heat transfer through the walls, roof and floor compared to conventional buildings. A wide range of thermal insulation materials can be used to provide the required high R-values (low U-values, typically in the 0.10 to 0.15 W/(m²·K) range). Special attention is given to eliminating thermal bridges.

To meet the requirements of the Passivhaus standard, windows are manufactured with exceptionally high R-values . These normally combine triple-pane insulated glazing with air-seals and specially developed thermally broken window frames.

Building envelopes under the Passivhaus standard are required to be extremely airtight compared to conventional construction. They are required to meet either 0.60 ACH50 (air changes per hour at 50 pascals) based on the building's volume.

In addition to using passive solar gain, Passivhaus buildings make extensive use of their intrinsic heat from internal sources—such as waste heat from lighting, white goods (major appliances) and other electrical devices (but not dedicated heaters)—as well as body heat from the people and other animals inside the building. This is due to the fact that people, on average, emit heat equivalent to 100 watts each of radiated thermal energy.

Typically, passive houses feature:

Fresh, clean air: Note that for the parameters tested, and provided the filters are maintained, HEPA quality air is provided. 0.3 air changes per hour are recommended, otherwise the air can become "stale" and any greater, excessively dry. This implies careful selection of interior finishes and furnishings, to minimize indoor air pollution from VOC's . This can be counteracted somewhat by opening a window for a very brief time, by plants, and by indoor fountains.

Because of the high resistance to heat flow, there are no "outside walls" which are colder than other walls.

Homogeneous interior temperature: it is impossible to have single rooms at a different temperature from the rest of the house. Note that the relatively high temperature of the sleeping areas is physiologically not considered desirable by some building scientists. Bedroom windows can be cracked open slightly to alleviate this when necessary.

Slow temperature changes: with ventilation and heating systems switched off, a passive house typically loses less than 0.5 °C per day, stabilizing at around 15 °C in the central European climate.

Quick return to normal temperature: opening windows or doors for a short time has only a limited effect; after apertures are closed, the air very quickly returns to the "normal" temperature.

Some have voiced concerns that Passivhaus is not a general approach as the occupant has to behave in a prescribed way, for example not opening windows too often. However modelling shows that such concerns are not valid.

References

1. Gröndahl, Mika; Gates, Guilbert. "The Secrets of a Passive House". The New York Times.

2. Feist, Wolfgang. "15th Anniversary of the Darmstadt - Kranichstein Passive House".

3. Delleske, Andreas. "What is a Passive house?".

4. https://en.wikipedia.org.

5. http://community.worldheritage.org/

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