Passive houses

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design of eco-friendly houses, hermetically sealed homes for tropical uplands

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Passive houses

  1. 1. A Seminar Report on THERMALLY-COMFORTABLE PASSIVE HOUSES FOR TROPICAL UPLANDS For The Subject of ‘Elements of Civil Engineering’ -Compiled by: Pratheek Manjunath 2nd Semester, EEE RVCE, Bangalore
  2. 2. CONTENTS 1. PREFACE 2. INTRODUCTION 3. DESIGN &CONSTRUCTION 4. CHARACTERISTICS & TRAITS 5. ADVANTAGES OVER CONVENTIONAL HOMES 6. BIBLIOGRAPHY
  3. 3. PREFACE In many countries located close to the equator, such as India, Sri Lanka, Myanmar, Thailand, Malaysia, Indonesia, and countries in parts of Africa and South America, certain regions can be considered tropical uplands. Tropics of the world highlighted In such regions, the cold discomfort that occurs during the night and warm discomfort that occurs during the daytime could become a problem unless houses are planned with careful consideration. This led architects and designers to come up with an ingenious idea of house-planning. These types of houses are called ‘Passive’ houses. INTRODUCTION
  4. 4. What is a ‘passive’ house? A passive house is a building in which a comfortable interior climate can be maintained without active heating and cooling systems. Essentially, the house heats and cools itself, hence "passive". The combined energy consumption of a passive house is less than the average new European home requires for household electricity and hot water alone. The combined end energy consumed by a passive house is therefore less than a quarter of the energy consumed by the average new construction that complies with applicable national energy regulations. How does it work? There are four key areas that comprise the Passive Home system: 1. Very high levels of insulation with minimal thermal bridges (glossary) 2. Intelligent use of solar and internal gains 3. Excellent level of airtightness 4. Good indoor air quality provided by a mechanical ventilation system With these features in place, a Passive House does not need a traditional heating system or active cooling to be comfortable to live in. HISTORY The term passive house, Passivhausin German means ‘Energy efficiency in a Building’. The Passivhaus standard originated from a conversation in May 1988 between Professors Bo Adamson of Lund University, Sweden, and Wolfgang Feist of the 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.
  5. 5. The first Passivhaus residences were built in Darmstadt, Germany in 1990, and occupied by the clients of the professors’ firm. PRESENT DAY SENARIO Current day estimate is that there are around20,000 passive houses around the world. Based on research and study of the existing passivhauses, designers have arrived at a standard for all technicalities and construction specifications and have termed it as 'Passivhaus Planning Package' (PHPP). The standard is not confined to residential properties; several office buildings, schools, kindergartens and a supermarket have also been constructed to the standard. DESIGN & CONSTRUCTION To achieve the standards of PHPP, a number of techniques and technologies are used in combination. 1) Passive solar design and landscape 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 principle windows oriented towards the equator - south in the northern hemisphere and north in the southern hemisphere - to maximize passive solar gain. However, the use of solar gain, especially in
  6. 6. temperate climate regions, is secondary to minimizing the overall house energy requirements. In climates and regions needing to reduce excessive summer passive solar heat gain, whether from the direct or reflected sources, can be done with trees attached with vines; vertical gardens, green roofs and other techniques. 2) Super-insulation 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 (typically in the range of 0.10 to 0.15 W/m²K). 3) Airtightness Building envelopes under the Passivhaus standard are required to be extremely airtight compared to conventional construction. Air barriers, careful sealing of every construction joint in the building envelope, and sealing of all service penetrations through it are all used to achieve this. Airtightness minimizes the amount of warm - or cool- air that can pass through the structure, enabling the mechanical ventilation system to recover the heat before discharging the air externally. 4) Window Technology To meet the requirements of the Passivhaus standard, windows are manufactured with exceptionally high R-values (typically 0.85 to 0.70 W/(m².K) for the entire window including the frame). These normally combine triple-pane insulated glazing (with a good solar heat-gain coefficient, low- emissivity coatings, sealed argon or krypton gas filled inter-pane voids, and 'warm edge' insulating glass spacers) with air-seals and specially developed thermally broken window frames. 5) Ventilation Passive methods of natural ventilation by singular or cross ventilation; by a simple opening or enhanced by the stack effect from smaller ingress - larger egress windows and/or clerestory-open able skylight use; is obvious when the exterior temperature is acceptable. 6) Dehumidification: In tropical climatic conditions, it is imperative to remove excess moisture from within the house. Hence, dehumidifiers working on solar power are adopted in some cases. Even solar air-conditioning exists which have a cooling capacity equivalent to 1ton. 7) Lighting and electrical appliances To minimize the total primary energy consumption, the many passive and active daylight techniques are the first daytime solution to employ. For low light level days, non-day lighted spaces, and nighttime; the use of creative-sustainable lighting design using low-energy sources such as 'standard voltage' compact fluorescent lamps and LED/OLED/PLEDlamps; and 'low voltage' Incandescent bulbs, and compact Halogen lamps, can be used. Solar powered exterior circulation, security, and landscape lighting - with photovoltaic cells on each fixture or connecting to a central Solar panel system, are available for gardens and outdoor needs.Timers, motion detection and natural light operation sensors reduce energy consumption. Consumer appliances must meet the certified energy star agency’s norms. The appliances should have a certificate of power rating on them.
  7. 7. CHARACTERISTICS Due to their design, passive houses usually have the following traits: The air is fresh, and very clean. Note that for the parameters tested, and provided the filters (minimum F6) are maintained, HEPA quality air is provided. 3 air changes per hour (ACH) are recommended, otherwise the air can become "stale" (excess CO2, flushing of indoor air pollutants) and any greater, excessively dry (less than 40% humidity). This implies careful selection of interior finishes and furnishings, to minimize indoor air pollution from VOC's (e.g., formaldehyde). The use of a mechanical venting system also implies higher positive ion values. This can be counteracted somewhat by opening a window for a very brief time, by plants, and by indoor fountains. However, failure to exchange air with the outside during occupied periods is not advisable. Because of the high resistance to heat flow (high R-value insulation), there are no "outside walls" which are colder than other walls. Inside temperature is homogeneous; it is impossible to have single rooms (e.g. the sleeping 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. The temperature changes only very slowly - with ventilation and heating systems switched off, a passive house typically loses less than 0.5 °C (1 °F) per day (in winter), stabilizing at around 15 °C (59 °F) in the central European climate. Opening windows or doors for a short time has only a very limited effect; after the windows are closed, the air very quickly returns to the "normal" temperature.
  8. 8. ADVANTAGES OVER CONVENTONAL HOMES Sustainability: A Passive House requires as little as 10 percent of the energy used by typical central European buildings. Vast have also been demonstrated in warm climates where buildings typically require active cooling throughout the summer. As energy savings equals emissions reductions, the Passive House is a sustainable alternative to conventional construction. Affordability: Passive Houses not only save money over the long term, especially in light of rising energy costs, but are surprisingly affordable to begin with. The investment in higher quality building components required by the Passive House standard is mitigated by the elimination of expensive heating and cooling systems. The financial support increasingly available in many countries makes building a Passive House all the more feasible. Even so, Passive Houses do cost more upfront than their conventional counterparts. On average, someone building a Passive House might expect to spend more, and this cost differential is likely more in countries where Passive House components are not yet readily available. As the number of Passive House suitable components on the market increases, however, prices in these countries will drop. Financial support for Passive Houses, as currently available in a number of countries, further reduces their cost. In this light then, building a Passive House may even be more affordable over the long term than building a conventional home. Comfort:Passive Houses may be known for their drastically lower energy use and associated energy costs, but it is the level of comfort they offer that their residents appreciate most. An extremely well insulated building envelope as well as triple glazed windows and insulated frames keep the desired warmth or lack thereof inside. This means that the floor and all interior walls stay at the same pleasant temperature. Along with comfort, aesthetics may also be given a lot of importance. The houses look modern and hi-tech! Versatile:The Passive House Standard, being a quality standard, dictates no particular methods of construction. Whether solid construction, wood or composite- architects can design Passive Houses according to their own preferences. This gives the builder and owner a lot of flexibility for design and choice of materials. As the Passive House concept is based on physical principles, each building can and should be adapted to a particular climate.
  9. 9. BIBLIOGRAPHY The information presented in the report was referenced from various websites. Wikipedia- http://en.wikipedia.org/wiki/Passive-houses International Passive House Association - http://www.passivehouse- international.org/index.php?page_id=79&level1_i http://www.sciencedirect.com/science/tcphpdf087?2/ http://www.passivhaustagung.de/Passive_House http://www.wolf-thermomodule.de/en/passivhaus.php The images were gathered through ‘Google Images’. -Compiled by: Pratheek Manjunath 2nd Semester, EEE RVCE Bangalore

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