Celsius Toolbox Glossary

A chiller using heat to supply cooling. There are many different types of absorption chillers, but they all work on a similar principle. In a low-pressure system, an absorption fluid is evaporated, removing heat from the chilled water. A heat source such as steam, exhaust gas or hot water is used to regenerate the absorption solution.

An absorption heat pump is an air-source heat pump driven not by electricity, but by a heat source such as solar-heated water, or geothermal-heated water.

An actuator is a component of a machine that is responsible for moving and controlling a mechanism or system, for example by opening a valve. In simple terms, it is a "mover".

An actuator requires a control signal and a source of energy. The control signal is relatively low energy and may be electric voltage or current, pneumatic or hydraulic pressure, or even human power. Its main energy source may be an electric current, hydraulic fluid pressure, or pneumatic pressure. When it receives a control signal, an actuator responds by converting the signal's energy into mechanical motion.

Antifouling is the ability of specifically designed materials and coatings to remove or prevent biofouling by any number of organisms on wetted surfaces.

Artificial neural networks (ANN) are computing systems that are inspired by, but not identical to, biological neural networks that constitute animal brains. Such systems "learn" to perform tasks by considering examples, generally without being programmed with task-specific rules.

Automatic balancing valves are utilised in central heating and cooling systems that rely on a flow of water through the system. They use the latest flow technology to ensure that the design flow rate is achieved at all times irrespective of any pressure changes within the system.

Building Research Establishment's (BRE) Environmental Assessment Method is a best practice standard for the environmental performance of buildings through design, specification, construction and operation.

BREEAM (Building Research Establishment Environmental Assessment Method) is a sustainability assessment method that is used to masterplan projects, infrastructure and buildings. Launched in 1990, by the Building Research Establishment (BRE) it sets standards for the environmental performance of buildings through the design, specification, construction and operation phases and can be applied to new developments or refurbishment schemes.

Coefficient of Performance is a metric for heat pumps. Defined as the ratio of the heating or cooling provided by the heat pump to the work consumed by the heat pump.

The Context and Critical Conditions tool (CCC) may be of help to sort the context in relation to time and system levels, and also to focus on what the critical contextual conditions are for the change.

Cost–benefit analysis (CBA), sometimes also called benefit–cost analysis or benefit costs analysis, is a systematic approach to estimating the strengths and weaknesses of alternatives used to determine options which provide the best approach to achieving benefits while preserving savings.

Demand response is a change in the power consumption of an electric utility customer to better match the demand for power with the supply.

System for distribution of cooling in a district or city.

System for distribution of heating in a district or city.

Digital up converter, increases the sample rate of signals.

In domestic installations, potable water heated for uses other than space heating is also called domestic hot water (DHW).

An energy audit is an inspection survey and an analysis of energy flows for energy conservation in a building. It may include a process or system to reduce the amount of energy input into the system without negatively affecting the output.

The Energy Performance of Buildings Directive (EPBD) is the European Union’s main legislative instrument aiming to promote the improvement of the energy performance of buildings within the Community. It was inspired by the Kyoto Protocol which commits the EU and all its parties by setting binding emission reduction targets.

The method of Energy potential mapping (EPM) aims to visualise the energy potentials and demands by making information on quantity, quality and location of demand and supply accessible. The aspect of quality specifically applies to heat and cold.

An energy service company (ESCO) is a business that provides a broad range of energy solutions including designs and implementation of energy savings projects, retrofitting, energy conservation, energy infrastructure outsourcing, power generation and energy supply, and risk management.

The Energy Technology Systems Analysis Program (ETSAP) is one of the longest running Technology Collaboration Programme of the International Energy Agency (IEA). ETSAP currently has as contracting parties 20 countries, the European Commission and two private sector sponsors.

The Environmental Protection Agency (EPA) is an independent agency of the United States federal government for environmental protection.

A forced-air central heating system is one which uses air as its heat transfer medium. These systems rely on ductwork, vents, and plenums as means of air distribution, separate from the actual heating and air conditioning systems.

Fouling is the accumulation of unwanted material on solid surfaces to the detriment of function. The fouling materials can consist of either living organisms (biofouling) or non-living substances (inorganic and/or organic). Fouling is usually distinguished from other surface-growth phenomena in that it occurs on a surface of a component, system, or plant performing a defined and useful function and that the fouling process impedes or interferes with this function.

A geo-fence is a virtual perimeter for a real-world geographic area. A geo-fence could be dynamically generated—as in a radius around a point location, or a geo-fence can be a predefined set of boundaries (such as school zones or neighbourhood boundaries).

The use of a geo-fence is called geo-fencing, and one example of usage involves a location-aware device of a location-based service (LBS) user entering or exiting a geo-fence. This activity could trigger an alert to the device's user as well as messaging to the geo-fence operator. This info, which could contain the location of the device, could be sent to a mobile telephone or an email account.

A geothermal heat pump (GHP) or ground source heat pump (GSHP) is a central heating and/or cooling system that transfers heat to or from the ground.

Heat exchanger is a device used to transfer heat between one or more fluids.

A heat pump is a device that transfers heat energy from a source of heat to a heat sink

High-temperature district cooling (HTDC) is district cooling system operating at temperatures just below the limit set by comfort temperature requirements.

Heating, ventilation and air conditioning (HVAC) is the technology of indoor and vehicular environmental comfort. 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.

Hydronics is the use of a liquid heat-transfer medium in heating and cooling systems. The working fluid is typically water, glycol, or mineral oil.

Information and communications technology (ICT) is an extensional term for information technology (IT) that stresses the role of unified communications and the integration of telecommunications (telephone lines and wireless signals) and computers, as well as necessary enterprise software, middleware, storage, and audiovisual systems, that enable users to access, store, transmit, and manipulate information.

The internal rate of return (IRR) is a measure of an investment’s rate of return. The term internal refers to the fact that the calculation excludes external factors, such as the risk-free rate, inflation, the cost of capital, or various financial risks.

Key Performance Indicators (KPI) evaluate the success of an organization or of a particular activity (such as projects, programs, products and other initiatives) in which it engages (e.g. COP, greenhouse gas emissions).

Leadership in Energy and Environmental Design (LEED) is one of the most popular green building certification programs used worldwide. Developed by the non-profit U.S. Green Building Council (USGBC) it includes a set of rating systems for the design, construction, operation, and maintenance of green buildings, homes, and neighborhoods that aims to help building owners and operators be environmentally responsible and use resources efficiently.

Low-Temperature District Heating. District heating systems operating at temperatures at or just above the limit set by domestic hot water temperature requirements.

Monte Carlo methods, or Monte Carlo experiments, are a broad class of computational algorithms that rely on repeated random sampling to obtain numerical results. The underlying concept is to use randomness to solve problems that might be deterministic in principle. They are often used in physical and mathematical problems and are most useful when it is difficult or impossible to use other approaches. Monte Carlo methods are mainly used in three problem classes: optimization, numerical integration, and generating draws from a probability distribution.

Net energy metering (NEM) or net metering, is an electricity billing mechanism that allows consumers who generate some or all of their own electricity to use that electricity anytime, instead of when it is generated. This is particularly important with renewable energy sources like wind and solar, which are non-dispatchable (when not coupled to storage).

The net present value (NPV) is the sum of the present values of the assets and cash flows (incoming and outgoing benefits or cost cash flows) over a period of time.

OJEU stands for the Official Journal of the European Union (previously called OJEC - the Official Journal of the European Community). This is the publication in which all tenders from the public sector which are valued above a certain financial threshold according to EU legislation, must be published.

Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry.

A prosumer is a person who consumes and produces a product. The term is derived from prosumption, a dot-com era business term meaning "production by consumers".

Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating.

A refrigerant is a substance or mixture, usually a fluid, used in a heat pump and refrigeration cycle. In most cycles, it undergoes phase transitions from a liquid to a gas and back again.

Retrofitting refers to the addition of new technology or features to older systems, for example:

• power plant retrofit, improving power plant efficiency / increasing output / reducing emissions
• home energy retrofit, the improvement of existing buildings with energy efficiency equipment
• seismic retrofit, the process of strengthening older buildings in order to make them earthquake-resistant
• Naval vessels often undergo retrofitting in dry dock to incorporate new technologies, change their operational designation, or compensate for perceived weaknesses in their design or gun plan.

The temperature in district heating or cooling distribution back from consumers to production facilities

Sensitivity analysis (SA) is the study of how the variation in the output of a system can be quantitatively apportioned to parameter variations.

The solar azimuth angle is the azimuth angle of the sun's position. This horizontal coordinate defines the sun's relative direction along the local horizon, whereas the solar zenith angle (or its complementary angle of solar elevation) defines the sun's apparent altitude.

In discussing solar energy, the solar savings fraction or solar fraction (fsol) is the amount of energy provided by the solar technology divided by the total energy required.

The temperature in district heating or cooling distribution from production facilities to consumers.

Thermal Energy Storage (TES) is achieved with widely differing technologies. Depending on the specific technology, it allows excess thermal energy to be stored and used hours, days, or months later, at scales ranging from the individual process, building, multiuser-building, district, town, or region.

Thermal shock is a type of rapidly transient mechanical load. By definition, it is a mechanical load caused by a rapid change in temperature at a certain point. It can be also extended to the case of a thermal gradient, which makes different parts of an object expand by different amounts.

The IEA works to ensure reliable, affordable and clean energy for its 30 member countries and beyond. The mission of IEA is guided by four main areas of focus: energy security, economic development, environmental awareness and engagement worldwide.

Infrared thermography (IRT), thermal imaging, and thermal video are examples of infrared imaging science. Thermographic cameras usually detect radiation in the long-infrared range of the electromagnetic spectrum (roughly 9,000–14,000 nanometers or 9–14 µm) and produce images of that radiation, called thermograms. Since infrared radiation is emitted by all objects with a temperature above absolute zero according to the black body radiation law, thermography makes it possible to see one's environment with or without visible illumination.

Underfloor heating and cooling is a form of central heating and cooling which achieves indoor climate control for thermal comfort using conduction, radiation and convection.

Underground thermal energy storage (UTES), in which the storage medium may be geological strata ranging from earth or sand to solid bedrock, or aquifers.