ASHRAE HBDP key terms

Computer modeling of a building's annual energy use by calculating heat flows, equipment performance, and schedules hour by hour. Designers use it to compare options and demonstrate compliance with performance-based codes.

A reference model representing the minimum code-compliant design, against which a proposed design is compared to show percentage energy savings. It must use the same geometry, schedules, and weather data as the proposed model.

Adjusting model inputs so simulated energy use closely matches measured utility data for an existing building. Calibration supports retrofit decisions and measurement-and-verification baselines.

Annual energy consumed per unit of floor area, typically expressed in kBtu per square foot or kWh per square meter. It normalizes consumption across buildings and supports benchmarking.

Comparing a building's energy performance against similar buildings or a national database using normalized metrics. Results identify poor performers and prioritize retrofit investment.

A typical meteorological year dataset of hourly temperature, humidity, and solar radiation for a location. Energy simulations use it to represent long-term average climate conditions.

A climate index summing, over a season, the degrees by which daily mean outdoor temperature falls below a reference base. It estimates heating loads and supports simplified energy comparisons.

A climate index summing, over a season, the degrees by which daily mean outdoor temperature exceeds a reference base. It estimates cooling loads and supports simplified energy comparisons.

Shaping building form, orientation, envelope, and shading so that heating, cooling, and daylighting needs are reduced before active systems are sized. It lowers loads rather than adding equipment efficiency.

Lowering peak and annual heating, cooling, and lighting demands through envelope, shading, and internal-load strategies. Smaller loads allow smaller, less costly mechanical systems.

How well the building skin resists heat flow, described by insulation level, glazing properties, airtightness, and thermal bridging. Strong performance reduces heating and cooling loads.

A path of high-conductance material that bypasses insulation, such as a balcony slab or steel stud. It causes localized heat loss, cold surfaces, and possible condensation.

Insulation placed outside the structural frame so it covers studs, slabs, and other penetrations without interruption. It reduces thermal bridging and improves effective R-value.

The area of glazing divided by the gross above-grade wall area of a facade. It strongly influences daylight, solar gain, and envelope heat loss, so codes often cap it.

The fraction of incident solar radiation admitted through glazing as heat, including absorbed and re-radiated energy. Lower values reduce cooling loads in sunny climates.

The ratio of solar heat gain through a given glazing assembly to that through clear single glazing under identical conditions. It predates and relates numerically to solar heat gain coefficient.

The capacity of building materials to store and later release heat, moderating indoor temperature swings. Exposed masonry or concrete can shift peak cooling loads to later hours.

Using controlled natural light to illuminate interior spaces and reduce electric lighting energy. Success depends on aperture design, glare control, and automatic dimming.

The percentage of occupied hours when a space reaches a target illuminance from daylight alone. It quantifies daylight sufficiency and supports lighting power reductions.

Excessive or poorly distributed brightness that causes discomfort or reduces visibility. Daylighting design controls it with shading, light shelves, and appropriate surface luminance.

The condition of mind expressing satisfaction with the thermal environment, influenced by air temperature, radiant temperature, humidity, air speed, clothing, and activity. Standards define acceptable ranges.

A comfort index predicting the average thermal sensation of a large occupant group on a scale from cold to hot. It pairs with predicted percentage dissatisfied to judge acceptability.

A single temperature combining air temperature and mean radiant temperature, weighted by air speed. It better represents occupant thermal sensation than dry-bulb air temperature alone.

The volumetric flow of outdoor air supplied to a space per unit time or per person and floor area. Adequate rates dilute contaminants and support occupant health and productivity.

Modulating outdoor-air supply based on measured occupancy, often via carbon dioxide sensors, rather than running at design flow continuously. It saves fan and conditioning energy while protecting air quality.

Measuring indoor carbon dioxide concentration as an indicator of occupancy and ventilation adequacy. Rising levels signal stale air or insufficient outdoor-air delivery.

The condition of air inside a building as it affects occupant health and comfort, shaped by pollutant sources, ventilation, filtration, and moisture control. Poor quality causes complaints and lost productivity.

Carbon-based chemicals that readily evaporate at room temperature, emitted by adhesives, coatings, and furnishings. Many irritate occupants, so low-emitting materials are specified.

Release of gases or particles from building products into indoor air over time. Specification of low-emitting products and flush-out procedures reduces occupant exposure.

A quality-focused process verifying that building systems are designed, installed, and operate to meet the owner's requirements. It begins in design and continues through handover and warranty.

A documented procedure that exercises a system under simulated conditions to confirm it responds correctly and meets specified performance. Results are recorded and deficiencies tracked to closure.

Applying the commissioning process to an existing building that was never commissioned, to identify and correct operational deficiencies. It typically delivers low-cost energy savings.

A structured method for quantifying savings from efficiency measures by comparing measured post-installation energy use with an adjusted baseline. It supports performance guarantees and persistence tracking.

Confirming that control logic, setpoints, and interlocks operate as written in the sequence of operations. Discrepancies are common causes of excess energy use.

Annual potable water consumption per unit of floor area or per occupant, used to compare buildings and track conservation results. It supports benchmarking and code compliance.

Using treated or captured water such as rainwater, greywater, or condensate for non-drinking purposes like flushing and irrigation. It reduces potable demand and site runoff.

An accounting of all water entering, leaving, and being stored within a building or site, including supply, reuse, and discharge. It sizes reuse systems and verifies conservation goals.

A method quantifying environmental impacts of materials and systems from extraction through disposal across defined stages. It informs comparisons among design alternatives beyond operating energy.

Greenhouse gas emissions associated with extracting, manufacturing, transporting, installing, and disposing of building materials. It complements operational emissions in whole-life carbon accounting.