Low-energy house

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A thermogram compares the "heat radiation" of the windows and walls of two buildings: sustainable low-energy passive house (right) and conventional leaking house (left)

A low-energy house is a building that has a very high energy performance and nearly zero or a very low amount of energy required. The house should be covered to a significant extent by energy from renewable sources, including energy produced on-site or nearby (provided that no public grid is used between their production and use).[1][2] In the practice of sustainable design, (or sustainable architecture, low-energy building, energy-efficient landscaping), low-energy houses often use active solar and passive solar building design techniques and components to reduce their energy expenditure.

Background[edit]

In the seventies many experimental initiatives towards low-energy buildings were made in countries like Denmark, the United States, Sweden, Canada and Germany until the German Passivhaus Institute introduced the first passive house in 1990. Today the implementation of standardized low-energy building concepts has developed differently in each country.[3]

United States[edit]

Interest in low-energy buildings has increased in the U.S. over the past few years mainly due to rising energy prices, decreasing costs for on-site renewable energy systems, and increasing concerns over climate change. For example, California now requires that all new residential construction be "zero net energy" by 2020.[4]

Germany[edit]

Triggered in the 1970s by the first energy crisis and a growing environmental consciousness, saving energy became increasingly important in Germany.[5] Due to these reasons, in 1977 an energy-related building standard was introduced by law for the first time. About ten years later, the annual heating requirement was introduced as an important parameter by the third German Thermal Insulation Ordinance (1995). However, in 2013 there is currently no clear legal requirement for the nearly zero-energy building standard in Germany. Some opinions presented by people like Fuller that a review about the definitions, policies and construction activity of zero energy buildings needs to be clear.[6] The law of Energy Performance Directive requires that from 2021 only nearly zero-energy buildings– very low energy demand in the utilization– may be built in the European Union.[7]

United Kingdom[edit]

Several changes to national policies have occurred in the period since May 2015 in the UK. One of the most significant has been the withdrawal of the Code for Sustainable Homes (CfSH) as a system for assessing and effectively encouraging improvements in the environmental design of dwellings.[8] This has meant the abandonment of the schematic which gave a framework of levels of achievement, which had been set up within the CfSH, and to which low energy designers could aspire to meet or surpass. Energy conservation legislation still exists as it did previously within the Building Regulations,[9] however there is something of a vacuum regarding suitable standards that exceed basic regulatory needs. As a result the Passive House Standard has the potential to expand its influence and impact in to energy efficient houses.[10]

National standards[edit]

In some countries the term relates to a specific building standard.[11] In particular, these seek to limit the energy used for space heating, since in many climate zones it represents the largest energy use. Other energy use may also be regulated. The history of passive solar building design gives an international look at one form of low-energy building development and standards.

Europe[edit]

Standards for low-energy buildings in Europe have proceeded differently in each country and today there is no common certification or legislation for low-energy buildings valid for all European member states. As a movement towards reducing energy use and emissions, a common legislation concerning buildings’ energy performance, the Energy Performance of Buildings Directive (EPBD) was published in 2002 and came into force January 2003.[12]

Norway[edit]

In the draft of the upcoming official standard NS 3700 low-energy buildings are defined. Concerning the buildings energy performance two alternatives for rating the primary energy are being discussed:

  • Limit values for the buildings annual CO2-emission; the emission shall be calculated by multiplying the annual supplied energy with CO2-factors;
  • Required percentage of the heating demand must be covered by renewable energy.

Denmark[edit]

Low-energy houses are defined in the national building regulation Building Regulations 08, divided into two classes; low-energy buildings class 1 and class 2. And they are regulated in chapter 7.2.4 Low-energy.

Germany[edit]

Low-energy houses certified by RAL-GZ 965 are mainly regulated by having 30% lower heat losses by transmission than regulated in the EnEV, a national building code. Besides there are other criteria on things like insulation, air tightness and ventilation. Low-energy buildings certified by the RAL-GZ 965 have two options:

  • Certified building for "Planning"
  • Certified building for "Construction"[13]

Switzerland[edit]

Low energy buildings are being promoted by non-profit organisation MINERGI®. MINERGI® is registered as a "quality label for new and refurbished buildings". "MINERGI-Standard" requires that buildings do not exceed more than 75% of the average building energy consumption and that fossil fuel consumption must not be higher than 50% of the consumption of such a buildings.[14]

North America[edit]

Whereas the recast of the European Union's directive has provided a focus for the clarification of low-energy houses in Europe, a large portion of the discussions on zero energy building in North America derive from the work at the U.S. National Renewable Energy Laboratory (NREL).[15]

United States[edit]

In the United States, the ENERGY STAR program is the largest program defining low-energy homes and consumer products. Homes earning ENERGY STAR certification use at least 15% less energy than standard new homes built to the International Residential Code, although homes typically achieve 20%–30% savings.[16]

In addition, the U.S. Department of Energy launched a program in 2008 with the goal of spreading zero-energy housing over the U.S..[17]

Canada[edit]

In Canada, builders may voluntarily use a range of standards, labels, and certification programs to demonstrate that they have achieved a very high level of energy performance in a given project. These include:

In British Columbia, all of the above programs align with the BC Energy Step Code, a provincial regulation that local governments may use, if they wish, to incentivize or require a level of energy efficiency in new construction that goes above and beyond the requirements of the base building code. The BC Energy Step Code is designed as a technical road map to help the province reach its target that all new buildings will attain a net zero energy ready level of performance by 2032.

Types of low-energy houses[edit]

Low-energy houses have a very broad definition and are generally known as houses with a lower energy demand than common buildings regulated in the national building code. The term low-energy house is in some countries used for a specific type of building and therefore the overall term buildings with lower heating demand include the different types, such as:[13]

Ultra house[edit]

Ultra houses are distinguished by the same characteristics as low-energy houses, but with additional focus on using building materials and components with better thermal technical qualities such as lower U-values.[13]

The difference between low-energy house & passive house[edit]

The low-energy house is rather a guideline and rarely specified in practical values--heat load or space heating minimum; passive house is a standard and gives specific recommendations in regard to the achievement of heating energy savings.

Another classifying method[edit]

At one end of the spectrum are buildings with an ultra-low space heating requirement that therefore require low levels of imported energy, even in winter, approaching the concept of an autonomous building.

At the opposite end of the spectrum are buildings where few attempts are made to reduce the space heating requirement and which therefore use high levels of imported energy in winter. While this can be balanced by high levels of renewable energy generation throughout the year, it imposes greater demands on the traditional national energy infrastructure during the peak winter season.

Barriers and opportunities for low-energy house[edit]

The take up of energy efficient design often relies on the use of new technologies and techniques which can introduce difficulties and problems because of their innovation. This can create technical barriers and risks, but there are also a number of social, cultural, and economic non-technical barriers. Whilst there are clearly some barriers, perhaps more importantly there are a range of opportunities too: opportunities to improve energy efficiency in buildings and opportunities for suitably skilled and knowledgeable professions to create cost efficient solutions.[10]

Low-energy technology[edit]

Introduction[edit]

The low energy design of buildings has been considered an important goal both to encourage resource efficiency and to reduce the potential for global climate change associated with the consumption of fossil fuels. Broadly speaking, the design involves two strategies – minimizing the need for energy use in buildings (especially for heating and cooling) through EEMs (energy-efficient measures) and adopting RETs (renewable energy and other technologies) to meet the remaining energy needs. EEMs include building envelopes, internal conditions, and building services systems; RETs cover photovoltaic or building-integrated photovoltaic, wind turbines, solar thermal (solar water heaters), heat pumps, and district heating and cooling. These include life-cycle cost and environmental impacts, climate change and social policy issues.[18]

The primary design strategy[edit]

Reduction of energy consumption is more environmentally and financially advantageous than simply increasing on-site production to achieve the low energy goal. The less a home consumes, then the smaller a renewable energy system it requires to reach nearly net-zero. Energy efficiency should always be the primary design strategy of a low-energy house.[1]

Improvements to heating, cooling, ventilation and water heating[edit]

Passive solar design and landscape[edit]

Passive solar building design and energy-efficient landscaping support the low-energy house in 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. However, the use of solar gain, especially in temperate climate regions, is secondary to minimizing the overall house energy requirements. On the other hand in hot climates temperatures excess heat can create uncomfortable indoor conditions. Passive alternatives to air conditioning systems such as temperature-dependent venting have been shown to be effective in regions with cooling needs.[19] Other techniques to combat excessive solar heat gains include brise-soleils, trees, attached pergolas with vines, vertical gardens, green roofs among others.

Low-energy houses can be constructed from dense or lightweight materials, but some internal thermal mass is normally incorporated to reduce summer peak temperatures, maintain stable winter temperatures, and prevent possible overheating in spring or autumn before the higher sun angle "shades" mid-day wall exposure and window penetration. Exterior wall color, when the surface allows choice, reflection or absorption qualities depends on the predominant year-round ambient outdoor temperature. The use of deciduous trees and wall trellised or self attaching vines can assist in climates not at the temperature extremes.

Lighting and electrical appliances[edit]

To minimize the total primary energy consumption, the many passive and active daylighting techniques are the first daytime solution to employ. For low light level days, non-daylight spaces, and nighttime; the use of creative-sustainable lighting design using low-energy sources such as 'standard voltage' compact fluorescent lamps and solid-state lighting with Light-emitting diode-LED lamps, organic light-emitting diodes, and PLED - polymer light-emitting diodes; and 'low voltage' electrical filament--Incandescent light bulbs, and compact Metal halide, Xenon and 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. Low voltage systems can be used for more controlled or independent illumination, while still using less electricity than conventional fixtures and lamps. Timers, motion detection and natural light operation sensors reduce energy consumption, and light pollution even further for a Low-energy house setting.

Appliance consumer products meeting independent energy efficiency testing and receiving Ecolabel certification marks for reduced electrical-'natural-gas' consumption and product manufacturing carbon emission labels are preferred for use in Low-energy houses. The ecolabel certification marks of Energy Star and EKOenergy are examples.

Summary[edit]

The best low energy designs not only produce reductions in energy costs but also offer occupants the potential for higher quality environments and more stable and controlled levels of thermal comfort.

See also[edit]

References[edit]

  1. ^ a b "Energy performance of net-zero and near net-zero energy homes in New England". Energy and Buildings. 67: 551–558. 2013-12-01. doi:10.1016/j.enbuild.2013.08.047. ISSN 0378-7788.
  2. ^ "The convergence of life cycle assessment and nearly zero-energy buildings: The case of Germany". Energy and Buildings. 76: 551–557. 2014-06-01. doi:10.1016/j.enbuild.2014.03.028. ISSN 0378-7788.
  3. ^ "European Embedding of Passive Houses" (PDF). www.pibp.pl. Retrieved 2018-12-10.
  4. ^ "Energy performance of net-zero and near net-zero energy homes in New England". Energy and Buildings. 67: 551–558. 2013-12-01. doi:10.1016/j.enbuild.2013.08.047. ISSN 0378-7788.
  5. ^ "Basiswissen Bauphysik" (PDF). www.newbooks-services.de. Retrieved 2018-12-10.
  6. ^ "Progress in ZEBs—A review of definitions, policies and construction activity". Energy Policy. 62: 196–206. 2013-11-01. doi:10.1016/j.enpol.2013.06.099. ISSN 0301-4215.
  7. ^ "32010L0031 - Richtlinie (EU) 31/2010". www.jurion.de. Retrieved 2018-12-10.
  8. ^ "2010 to 2015 government policy: energy efficiency in buildings". GOV.UK. Retrieved 2018-12-10.
  9. ^ "Conservation of fuel and power: Approved Document L". GOV.UK. Retrieved 2018-12-10.
  10. ^ a b Pitts, Adrian; Pitts, Adrian (February 2017). "Passive House and Low Energy Buildings: Barriers and Opportunities for Future Development within UK Practice". Sustainability. 9 (2): 272. doi:10.3390/su9020272.
  11. ^ Raad Z. Homod, (2014) “Assessment regarding energy saving and decoupling for different AHU (air handling unit) and control strategies in the hot-humid climatic region of Iraq” Energy, 74 (2014) 762-774
  12. ^ Linden, Belinda (February 2011). "Resuscitation guidelines: 2010 updateResuscitation Council UK, (2010) Resuscitation Guidelines 2010 October. http://www.resus.org.uk/ pages/guide.htm (accessed 14 January 2011)". British Journal of Cardiac Nursing. 6 (2): 84–86. doi:10.12968/bjca.2011.6.2.84. ISSN 1749-6403. External link in |title= (help)
  13. ^ a b c "Low-energy buildings in Europe – standards, criteria and consequences". lup.lub.lu.se. Retrieved 2018-12-10.
  14. ^ "Home". MINERGIE Schweiz. Retrieved 2018-12-10.
  15. ^ "Shifting from net-zero to net-positive energy buildings". www.tandfonline.com. doi:10.1080/09613218.2014.950452. Retrieved 2018-12-10. line feed character in |title= at position 46 (help)
  16. ^ "Features of ENERGY STAR Qualified New Homes." - EnergyStar.gov, Retrieved 7 March 2008.
  17. ^ "About Builders Challenge." Archived 2011-09-03 at the Wayback Machine. - March 2008. Energy Efficiency and Renewable Energy, U.S. Department of Energy. Retrieved 7 March 2008.
  18. ^ "Zero energy buildings and sustainable development implications – A review". Energy. 54: 1–10. 2013-06-01. doi:10.1016/j.energy.2013.01.070. ISSN 0360-5442.
  19. ^ Reda, F., Tuominen, P., Hedman, Å., Ibrahim, M.G.E.: Low-energy residential buildings in New Borg El Arab: Simulation and survey based energy assessment. Energy and Buildings, Volume 93, 15 April 2015, Pages 65-82.

Literature[edit]

  • Voss, Karsten and Musall, Eike: Net zero energy buildings - International projects of carbon neutrality in buildings 2nd edition, November 2012, Institut für internationale Architektur-Dokumentation GmbH & Co. KG, München, ISBN 978-3-920034-80-5
  • Raad Z. Homod, Intelligent HVAC Control for High Energy Efficiency in Buildings,LAP LAMBERT Academic Publishing, (2014), ISBN 978-3-8473-0625-2.

External links[edit]

External links - examples[edit]