Glossaire

An air handling unit conditions and moves air through a ventilation system. Depending on its configuration, it may filter, heat, cool or recover heat from air.

An air-source heat pump transfers heat between outdoor air and a building’s heating or cooling system. It can supply warm air or heated water, depending on its design.

An application programming interface is a defined way for software systems to exchange data or request functions, supporting connections between building platforms and other applications.

BACnet is a standard communication protocol that enables building automation devices and systems to exchange data, commands and status information.

Baseload is the relatively persistent level of demand present across a defined period. In buildings, it can include essential equipment and systems running continuously.

Boiler short cycling is frequent starting and stopping over short periods. It can arise from oversizing, low demand or control issues and may reduce efficiency.

BREEAM is a sustainability assessment and certification framework for buildings and other built-environment projects. The criteria depend on the selected scheme and project type.

The valuation penalty applied to energy-inefficient buildings relative to comparable, better-rated assets. The inverse of the green premium.

A building automation and control system combines equipment, software and control functions to manage building services automatically. It overlaps with the terms BMS and building automation system.

Building control optimisation improves control settings, schedules and operating sequences so equipment responds more effectively to demand and operating constraints.

Building data quality describes whether information is sufficiently accurate, complete, consistent and timely for its intended use. Poor data can undermine control, analysis and reporting.

Building decarbonisation reduces greenhouse gas emissions associated with a building through measures such as lowering energy demand, changing energy sources and reducing material-related emissions.

A building digital twin is a digital representation linked to information about a physical building. Its detail, update frequency and analytical capabilities depend on its purpose.

A building energy management system monitors and controls building services with a focus on energy performance. Its functions often overlap with those of a building management system.

Building energy optimisation is the process of improving how building systems operate to reduce energy use while maintaining required comfort, safety and service levels.

A building management system supervises and controls building services such as heating, ventilation and cooling. Its capabilities depend on the installed equipment, configuration and access permissions.

The building performance gap is the difference between predicted and actual building performance. It can result from modelling assumptions, installation issues, operating practices or occupant behaviour.

Capital expenditure is spending on acquiring, replacing or substantially improving long-term assets, such as building plant or insulation. Accounting treatment depends on the expenditure and applicable rules.

Carbon dioxide equivalent expresses the warming impact of different greenhouse gases using a common unit based on their global warming potentials over a specified time horizon.

Carbon intensity is greenhouse gas emissions per unit of activity, energy or floor area. Building comparisons must specify the denominator, reporting period and emissions boundary.

A chiller removes heat from a liquid, usually water, which is then circulated to provide cooling to building spaces or equipment.

Closed-loop control uses measured feedback to adjust equipment towards a target condition, such as changing heating output in response to room temperature.

Coefficient of performance is useful heating or cooling output divided by energy input at specified conditions. A heating COP of three means three units of heat per unit of input.

Commissioning is a structured process of checking, testing and documenting that building systems meet specified requirements and operate as intended.

A condensing boiler recovers additional heat by condensing water vapour in its exhaust gases. Its ability to condense depends partly on sufficiently low return-water temperatures.

Continuous commissioning uses ongoing monitoring, analysis and corrective action to maintain and improve building-system performance over time.

A control sequence describes how equipment should respond to operating conditions, including start-up, shutdown, staging, interlocks and changes in demand.

Cooling degree days measure how much and for how long outdoor temperatures exceed a selected base temperature. They help explain weather-related cooling demand.

CSRD is an EU directive establishing sustainability reporting requirements for companies within its scope. Applicability and implementation timing must be checked against current legislation.

The Carbon Risk Real Estate Monitor. Science-based decarbonisation pathways for real estate, used to identify which assets are on track and which face stranding risk.

CRREM Misalignment Year is the projected year when an asset’s performance exceeds its applicable CRREM pathway. Formerly called “stranding year,” it indicates climate-pathway misalignment rather than a definitive loss of asset value.

A deadband is a range within which a controller takes no corrective action. In temperature control, it can separate heating and cooling thresholds.

A decarbonisation pathway describes how emissions should reduce over time towards a target. A building’s measured or projected performance can be compared with that trajectory.

A deep retrofit combines substantial improvements across building systems and fabric to achieve a major reduction in energy demand or emissions. The threshold depends on the framework used.

Demand response changes electricity consumption in response to a signal, incentive or system need, such as shifting flexible building loads away from periods of high demand.

Demand-controlled ventilation adjusts ventilation airflow according to indicators of demand, such as occupancy or carbon dioxide concentration, within required ventilation limits.

A Display Energy Certificate shows a building’s operational energy performance using actual consumption data, with adjustments under the applicable scheme. In England and Wales, it applies to qualifying public buildings.

A heat network distributes heat from one or more sources to multiple buildings or users through insulated pipes. Its emissions depend on the heat sources and system performance.

Domestic hot water is heated water supplied for washing, bathing and similar uses, separate from water circulating through a space-heating system.

Embodied carbon refers to greenhouse gas emissions associated with materials and construction activities across specified life-cycle stages, including production, transport, installation, replacement and disposal.

An emission factor converts activity data, such as fuel or electricity consumption, into an estimate of greenhouse gas emissions for a specified source, location and period.

An energy audit is a systematic assessment of energy use that identifies opportunities to improve efficiency. Its depth can range from an initial review to detailed engineering analysis.

An energy baseline is a reference level of energy consumption used to assess changes in performance. Its period, operating conditions and measurement boundary must be defined.

Energy benchmarking compares a building’s performance with its own historical results or suitable peer buildings, using consistent metrics and accounting for relevant differences.

An energy conservation measure is an operational or physical change intended to reduce energy consumption, such as correcting schedules, improving controls or upgrading equipment.

An Energy Performance Certificate rates a building’s assessed energy performance and identifies potential improvements. Assessment methods and rating scales depend on the jurisdiction; it is not a direct record of actual consumption.

An energy retrofit upgrades an existing building to improve energy performance. Measures can include controls, equipment, insulation, glazing and changes to energy supply.

ESOS is a UK scheme requiring qualifying organisations to assess energy use and identify energy-saving opportunities. Eligibility, reporting and compliance requirements are defined in current government guidance.

Energy use intensity is a building’s energy consumption divided by its floor area over a defined period, commonly expressed as kWh/m²/year. Comparisons require consistent boundaries and floor-area definitions.

The EU Energy Performance of Buildings Directive. Sets binding national renovation targets, plus solar and EV charging requirements.

Estimated energy savings are predicted reductions based on calculations, models or assumptions. They describe potential benefits before those benefits have been demonstrated through measurement.

The EU Taxonomy is a classification system for environmentally sustainable economic activities. Alignment requires meeting applicable criteria, rather than simply describing an activity as green.

ESRS specify sustainability information reported by companies subject to the applicable CSRD requirements, covering environmental, social and governance topics.

Fault detection and diagnostics uses operating data and analytical rules or models to identify abnormal system behaviour and investigate its likely causes.

Flow temperature is the temperature of water leaving a heating or cooling source to supply the distribution system. It influences heat delivery and system efficiency.

A green lease includes provisions supporting environmental performance, such as energy-data sharing, cooperation on improvements and agreed responsibilities between landlord and tenant.

A green premium is an observed price or rental advantage associated with stronger environmental characteristics. Its presence and size depend on the market and supporting evidence.

The benchmark institutional investors use to compare real estate funds on sustainability performance, built from asset-level data.

A ground-source heat pump exchanges heat with the ground through buried pipes or boreholes to provide building heating and, in suitable systems, cooling.

Heat electrification replaces fossil-fuel heating with electrically powered alternatives, such as heat pumps. Its carbon impact depends on equipment efficiency and electricity emissions.

A heat pump uses electricity to transfer heat from one place to another for heating or cooling. Its efficiency depends on temperatures, design and operating conditions.

Heat recovery captures heat that would otherwise be rejected and uses it elsewhere, such as transferring heat from exhaust air to incoming ventilation air.

The rule that sets flow temperature against outside temperature. One of the most common sources of avoidable energy waste in a building.

Heating degree days measure how much and for how long outdoor temperatures fall below a selected base temperature. They help explain weather-related heating demand.

HVAC stands for heating, ventilation and air conditioning: the systems that manage indoor temperature, air supply and, where provided, humidity.

Hydraulic balancing adjusts water flow through heating or cooling circuits so each part receives the required flow, supporting effective heat distribution and control.

IPMVP is a framework for planning and reporting measurement and verification of energy and water savings. It provides approaches suited to different projects and measurement boundaries.

The Internet of Things connects physical devices, such as sensors and meters, so they can collect and exchange data through communication networks.

Interval data records consumption or other measurements at regular time steps, such as every 15 or 30 minutes, revealing patterns that monthly totals can hide.

ISO 50001 is an international standard for energy management systems, providing a framework to establish objectives, measure performance and continually improve energy management.

ISO 52120-1 provides a framework for assessing how building automation, controls and technical building management contribute to building energy performance.

Measurement and verification is the process of quantifying energy savings by comparing measured performance with an appropriately adjusted baseline using a documented method.

Minimum Energy Efficiency Standards. The UK regulation that makes it unlawful to let property below a set EPC rating.

Modbus is a communication protocol used to exchange data between devices such as meters, controllers and industrial equipment over serial or network connections.

Model predictive control uses a model and forecasts to select control actions over a future time horizon, while respecting constraints such as comfort limits and equipment capacity.

Net asset value is the value of an entity’s assets minus its liabilities. For property portfolios, valuation assumptions and liabilities influence the reported figure.

Rental income less operating expenses. Energy is one of the few operating costs an owner can reduce without touching the lease.

Net present value is the present value of an investment’s expected future cash flows minus its initial cost, calculated using a stated discount rate.

A net zero carbon building balances emissions within a stated boundary and period after substantial reductions, addressing residual emissions under the chosen framework. Operational and whole-life claims differ.

The reference consumption an asset would have had without intervention, adjusted for weather and occupancy. What savings claims are measured against.

Operating expenditure is spending on ongoing operations, such as energy, maintenance and services. Whether a cost falls to an owner or tenant depends on contractual arrangements.

Operational carbon refers to greenhouse gas emissions arising from a building’s operation, including energy used for heating, cooling, ventilation, lighting and equipment. The reporting boundary should be stated.

Operational energy performance describes how much energy a building actually uses under real operating conditions, including its occupancy, weather and equipment schedules.

Optimum start and stop controls adjust equipment operating times so required conditions are reached when needed, while limiting unnecessary operation before or after occupancy.

Out-of-hours energy use is consumption outside a building’s intended occupied or operating periods. Some is necessary; avoidable consumption may indicate scheduling or control problems.

Peak demand is the highest rate of energy use recorded during a defined interval. It affects equipment capacity requirements and, under some tariffs, energy charges.

A plant room is a space containing building services equipment, such as boilers, pumps, heat exchangers and associated controls.

Recommissioning repeats commissioning activities in a previously commissioned building to address changed requirements, deterioration or operational problems.

Retro-commissioning applies a commissioning process to an existing building that was not previously commissioned, identifying and correcting operational problems.

A retrofit roadmap sets out a sequence of building improvements over time, considering performance targets, equipment replacement cycles, costs and dependencies between measures.

Return on investment compares the net financial benefit of an investment with its cost. The calculation should state the period, included costs and included benefits.

Return temperature is the temperature of water returning from the distribution system to the heating or cooling source after exchanging heat.

Direct emissions from fuel burned on site, and indirect emissions from purchased energy. Together they make up a building's operational carbon footprint.

Scope 3 emissions are indirect value-chain emissions outside an organisation’s Scope 2 emissions. For property businesses, they can include relevant tenant operations, purchased materials and investments.

Seasonal coefficient of performance represents heat-pump heating efficiency across standardised seasonal conditions, rather than at a single operating point. Actual building performance may differ.

The target value a control system works toward — a room temperature, a flow temperature, a ventilation rate. Where optimisation actually happens.

Simple payback period is the upfront investment divided by annual net savings. It does not account for the time value of money or benefits after payback.

Solar photovoltaic systems convert sunlight into electricity. Their output depends on factors including installed capacity, orientation, shading and local solar conditions.

Solar self-consumption is the share of electricity generated by a solar PV system that is used on site rather than exported. The calculation boundary should be specified.

A split incentive occurs when the party paying for an energy improvement does not receive all its benefits, as when a landlord funds upgrades but tenants save on bills.

A stranded asset is an asset whose economic value or usefulness is impaired by changes such as market expectations, technology or regulation. A pathway exceedance alone does not prove financial stranding.

SECR is a UK reporting framework requiring qualifying companies and limited liability partnerships to disclose specified energy and greenhouse gas information in their annual reports.

Submetering measures energy or water use separately for particular systems, spaces or tenants within a building, providing detail beyond the main utility meter.

Temperature differential is the difference between two measured temperatures, often the flow and return temperatures of a heating or cooling circuit.

Tenant emissions are emissions associated with a tenant’s activities, including energy use in leased premises. Their classification in landlord and tenant inventories depends on reporting boundaries and control.

Transition risk is financial or operational exposure arising from the shift towards a lower-carbon economy, including changes in policy, technology, demand and investor expectations.

A variable-speed drive controls an electric motor’s speed to match demand. In suitable pump and fan applications, it can reduce energy use compared with constant-speed operation.

Verified energy savings are reductions in energy use established through a documented measurement and verification process that accounts for relevant changes in operating conditions.

Weather compensation adjusts heating flow temperature in response to outdoor temperature, typically supplying cooler water in milder weather and warmer water when it is colder.

Weather normalisation adjusts energy consumption or a baseline to account for weather differences, allowing more meaningful comparisons between periods with different heating or cooling requirements.