Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. "Refrigeration" is sometimes added to the field's abbreviation as HVAC&R or HVACR, or "ventilation" is dropped, as in HACR.
A low-energy house is characterized by an energy-efficient design and technical features which enable it to provide high living standards and comfort with low energy consumption and carbon emissions. Traditional heating and active cooling systems are absent, or their use is secondary. Low-energy buildings may be viewed as examples of sustainable architecture. Low-energy houses often have active and passive solar building design and components, which reduce the house's energy consumption and minimally impact the resident's lifestyle. Throughout the world, companies and non-profit organizations provide guidelines and issue certifications to guarantee the energy performance of buildings and their processes and materials. Certifications include passive house, BBC—Bâtiment Basse Consommation—Effinergie (France), zero-carbon house (UK), and Minergie (Switzerland).
Passive house is a voluntary standard for energy efficiency in a building, which reduces the building's carbon footprint. Conforming to these standards results in ultra-low energy buildings that require less energy for space heating or cooling. A similar standard, MINERGIE-P, is used in Switzerland. Standards are available for residential properties and several office buildings, schools, kindergartens and a supermarket have also been constructed to the standard. The design is not an attachment or supplement to architectural design, but a design process that integrates with architectural design. Although it is generally applied to new buildings, it has also been used for refurbishments.
Building science is the science and technology-driven collection of knowledge in order to provide better indoor environmental quality (IEQ), energy-efficient built environments, and occupant comfort and satisfaction. Building physics, architectural science, and applied physics are terms used for the knowledge domain that overlaps with building science. In building science, the methods used in natural and hard sciences are widely applied, which may include controlled and quasi-experiments, randomized control, physical measurements, remote sensing, and simulations. On the other hand, methods from social and soft sciences, such as case study, interviews & focus group, observational method, surveys, and experience sampling, are also widely used in building science to understand occupant satisfaction, comfort, and experiences by acquiring qualitative data. One of the recent trends in building science is a combination of the two different methods. For instance, it is widely known that occupants' thermal sensation and comfort may vary depending on their sex, age, emotion, experiences, etc. even in the same indoor environment. Despite the advancement in data extraction and collection technology in building science, objective measurements alone can hardly represent occupants' state of mind such as comfort and preference. Therefore, researchers are trying to measure both physical contexts and understand human responses to figure out complex interrelationships.
A Zero-Energy Building (ZEB), also known as a Net Zero-Energy (NZE) building, is a building with net zero energy consumption, meaning the total amount of energy used by the building on an annual basis is equal to the amount of renewable energy created on the site or in other definitions by renewable energy sources offsite, using technology such as heat pumps, high efficiency windows and insulation, and solar panels.
Underfloor heating and cooling is a form of central heating and cooling that achieves indoor climate control for thermal comfort using hydronic or electrical heating elements embedded in a floor. Heating is achieved by conduction, radiation and convection. Use of underfloor heating dates back to the Neoglacial and Neolithic periods.
Building insulation is material used in a building to reduce the flow of thermal energy. While the majority of insulation in buildings is for thermal purposes, the term also applies to acoustic insulation, fire insulation, and impact insulation. Often an insulation material will be chosen for its ability to perform several of these functions at once.
Passive ventilation is the process of supplying air to and removing air from an indoor space without using mechanical systems. It refers to the flow of external air to an indoor space as a result of pressure differences arising from natural forces.
The Home Energy Rating is an American estimated measurement of a home's energy efficiency based on normalized modified end-use loads (nMEULs). In the United States, the Residential Energy Services Network (RESNET) is responsible for creation and maintenance of the RESNET Mortgage Industry National Home Energy Rating Standards (MINHERS), a proprietary system of standards, which includes standards language for the certification and quality assurance for RESNET Provider organizations. RESNET is an EPA recognized Home Certification Organization (HCO) that also help's create standards in compliance with the American National Standards Institute, namely ANSI 301, ANSI 310, ANSI 380, and ANSI 850. The Building Science Institute, Ltd. Co. (BSI) is another EPA recognized HCO that maintains the ANSI Standards to produce Energy Ratings and compliance with above-code programs such as the ENERGY STAR New Homes Program.
Design standards, reference standards and performance standards are familiar throughout business and industry, virtually for anything that is definable. Sustainable design, taken as reducing our impact on the earth and making things better at the same time, is in the process of becoming defined. Also, many well organized specific methodologies are used by different communities of people for a variety of purposes.
The International Energy Conservation Code (IECC) is a building code created by the International Code Council in 2000. It is a model code adopted by many states and municipal governments in the United States for the establishment of minimum design and construction requirements for energy efficiency. The code is updated every 3 years, to provide an ongoing standard of best practices for energy efficiency.
The International Green Construction Code (IGCC) is a set of guidelines that aim to improve the sustainability and environmental performance of buildings during their design, construction, and operation. It was introduced by the International Code Council (ICC), a non-profit organization that provides building safety and fire prevention codes for the United States and other countries. It is a model code designed to be mandatory where it is implemented.
A Deep energy retrofit can be broadly categorized as an energy conservation measure in an existing building also leading to an overall improvement in the building performance. While there is no exact definition for a deep energy retrofit, it can be defined as a whole-building analysis and construction process, that aims at achieving on-site energy use minimization in a building by 50% or more compared to the baseline energy use making use of existing technologies, materials and construction practices. Such a retrofit reaps multifold benefits beyond energy cost savings, unlike conventional energy retrofit. It may also involve remodeling the building to achieve a harmony in energy, indoor air quality, durability, and thermal comfort. An integrated project delivery method is recommended for a deep energy retrofit project. An over-time approach in a deep energy retrofitting project provides a solution to the large upfront costs problem in all-at-once execution of the project.
United States building energy codes are a subset of building codes that set minimum requirements for energy-efficient design and construction for new and renovated buildings. The intent of these energy codes is to moderate and reduce energy use and emissions throughout the lifetime of a building. Energy code provisions may include various aspects of building design and construction, such as: HVAC systems, building envelope, electrical, and lighting systems. There are building energy codes for both commercial and residential buildings. However, just as the United States does not have a national building code, it also does not have a national building energy code; rather, state, and local governments choose to adopt—and potentially revise—national model energy codes and standards. Consequently, building energy codes, and building codes in general, vary between states and jurisdictions.
ANSI/ASHRAE/IES Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings is an American National Standards Institute (ANSI) standard published by ASHRAE and jointly sponsored by the Illuminating Engineering Society (IES) that provides minimum requirements for energy efficient designs for buildings except for low-rise residential buildings. The original standard, ASHRAE 90, was published in 1975. There have been multiple editions to it since. In 1999 the ASHRAE Board of Directors voted to place the standard on continuous maintenance, based on rapid changes in energy technology and energy prices. This allows it to be updated multiple times in a year. The standard was renamed ASHRAE 90.1 in 2001. It has since been updated in 2004, 2007, 2010, 2013, 2016, and 2019 to reflect newer and more efficient technologies.
United States Lighting Energy Policy is moving towards increased efficiency in order to lower greenhouse gas emissions and energy use. Lighting efficiency improvements in the United States can be seen through different standards and acts. The Energy Independence and Security Act of 2007 laid out changes in lighting legislation for the United States. This set up performance standards and the phase-out of incandescent light bulbs in order to require the use of more efficient fluorescent lighting. EISA 2007 is an effort to increase lighting efficiency by 25-30%. Opposition to EISA 2007 is demonstrated by the Better Use of Light Bulbs Act and the Light Bulb Freedom of Choice Act. The efforts to increase lighting efficiency are also demonstrated by the Energy Star program and the increase efficiency goals by 2011 and 2013. A ban on the manufacture and sale of most general purpose incandescent bulbs in the U.S. took effect on August 1, 2023.
Sustainable refurbishment describes working on existing buildings to improve their environmental performance using sustainable methods and materials. A refurbishment or retrofit is defined as: "any work to a building over and above maintenance to change its capacity, function or performance' in other words, any intervention to adjust, reuse, or upgrade a building to suit new conditions or requirements". Refurbishment can be done to a part of a building, an entire building, or a campus. Sustainable refurbishment takes this a step further to modify the existing building to perform better in terms of its environmental impact and its occupants' environment.
The American Society of Heating, Refrigerating and Air-Conditioning Engineers is an American professional association seeking to advance heating, ventilation, air conditioning and refrigeration (HVAC&R) systems design and construction. ASHRAE has over 50,000 members in more than 130 countries worldwide.
Building performance simulation (BPS) is the replication of aspects of building performance using a computer-based, mathematical model created on the basis of fundamental physical principles and sound engineering practice. The objective of building performance simulation is the quantification of aspects of building performance which are relevant to the design, construction, operation and control of buildings. Building performance simulation has various sub-domains; most prominent are thermal simulation, lighting simulation, acoustical simulation and air flow simulation. Most building performance simulation is based on the use of bespoke simulation software. Building performance simulation itself is a field within the wider realm of scientific computing.
Ventilative cooling is the use of natural or mechanical ventilation to cool indoor spaces. The use of outside air reduces the cooling load and the energy consumption of these systems, while maintaining high quality indoor conditions; passive ventilative cooling may eliminate energy consumption. Ventilative cooling strategies are applied in a wide range of buildings and may even be critical to realize renovated or new high efficient buildings and zero-energy buildings (ZEBs). Ventilation is present in buildings mainly for air quality reasons. It can be used additionally to remove both excess heat gains, as well as increase the velocity of the air and thereby widen the thermal comfort range. Ventilative cooling is assessed by long-term evaluation indices. Ventilative cooling is dependent on the availability of appropriate external conditions and on the thermal physical characteristics of the building.
