What Are Zero Energy Building Materials?

Zero-energy building (ZEB), also referred to as net-zero-energy building, any building or building characterized by zero net energy consumption and zero measured over time carbon emissions. Zero-energy buildings (ZEBs) typically use less energy than conventional buildings and produce their own on-site energy for building use; many are also independent of the national (electricity) grid. In response to strict environmental requirements, both legislative and voluntary, ZEBs have emerged to resolve increasingly important environmental concerns such as climate change, conservation of natural resources, pollution, biodiversity and population.


Many people still live in zero-energy buildings in developing countries (and elsewhere) out of necessity, including huts, tents, and caves exposed to freezing temperatures and without access to electricity. Since the 1970s, the idea of a 'zero-energy house' has been debated in a modern context, sparked by the petroleum shocks of the decade and subsequent fears about the effects of reliance on fossil fuels.


ZEB concepts differ from those related to net energy inputs versus outputs to those that balance the economic costs of energy usage with the costs of equipment used in the energy production structure, such as photovoltaics (solar cells) and wind turbines, along with the advantages of exporting energy generated by the structure. Energy can be calculated in many ways in a building ( e.g. cost, energy or carbon emissions), and there are various opinions on the relative importance of energy production and energy efficiency in maintaining a net energy balance.


ZEB Energy Generation


To fulfill their electricity and heating or cooling needs, ZEBs need to generate their own energy on site. Different microgeneration technologies, including the following, may be used to supply heat and electricity to the house.:


  • Solar (solar hot water, photovoltaics [PV]).

  • Wind (wind turbines).

  • Biomass (heaters and stoves, boilers, and community heating schemes).

  • Combined heat and power (CHP) and micro-CHP for use with natural gas, biomass, sewerage gas, and other biogases.

  • Community heating (including utilizing waste heat from large-scale power generation).

  • Heat pumps (air source [ASHP] and ground source [GSHP] and geothermal heating systems).

  • Water (small-scale hydropower).

  • Other (including fuel cells using hydrogen generated from any of the above renewable sources).


Many homebuilders are seriously concerned about whether micro-generation and renewable energy technologies can fulfill the requirements for energy generation to generate sufficient, cost-effective working ZEBs. Builders worry that owners and occupiers will not embrace the modern technology needed and will prefer to retrofit energy-intensive appliances and systems that would eventually undermine the goals of zero energy. Further concerns exist that failure to properly maintain modern systems and technologies could expose owners and occupiers to health and safety risks.


Home Energy Rating System


A Home Energy Rating System (or HERS) is an energy efficiency indicator of a home used mainly in the United States. HERS ratings make use of the HERS Metric, a relative energy-use index. Usually, the HERS Index varies from 0 to 150, with a home with a score of 150 being highly energy intensive in terms of energy purchased. A HERS Index of 100 reflects the "American Standard House" energy usage and a zero index means that no net purchased energy (a zero-energy building) is used by the proposed building.


Some countries have systems that are similar. It is known as the National House Energy Rating Scheme in Australia and is based on a ten-star rating, and Energy Efficiency Certificates (EPCs) are graded from A to G in the United Kingdom. HERS offers a standardized estimate of the energy quality and projected energy costs of a building. The evaluation shall be performed in compliance with uniform standards and shall include a comprehensive assessment of home energy usage carried out by a state-certified assessor using a set of nationally validated procedures and software resources. The rating can be used to measure a home's current energy efficiency or to estimate the efficiency of a home being constructed or refurbished. A Home Energy Rating study was recommended by the U.S. Department of Energy, and would usually include the following:


  • Overall rating score of the house.

  • Recommended cost-effective energy modifications.

  • Estimates of the cost, annual savings, and useful projected life of the modifications.

  • After the implementation of recommended modifications, the future enhanced rating score.

  • The estimated projected annual energy costs, before and after the improvements, for the existing house.

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