Functional unit of buildings
The New Rules of Measurement (NRM) are published by the Royal Institute of Chartered Surveyors (RICS). They provide a standard set of measurement rules for estimating, cost planning, procurement and whole-life costing for construction projects.
According to NRM1: Order of cost estimating and cost planning for capital building work, a functional unit is: ‘…a unit of measurement used to represent the prime use of a building or part of a building (e.g. per bed space, per house and per m2 of retail area). It also includes all associated circulation space.'
NRM1 defines the functional unit method as: ‘…a rough budget-setting technique which consists of selecting a suitable standard functional unit of use for the project, and multiplying the projected number of units by an appropriate cost per functional unit.’
BRE's Environmental impact of biomaterials and biomass defines a functional unit as: '...a qualitative description of function specifically defined for the product/service under study and any alternative product/services to which it is compared. The use of a functional unit means that the alternative designs under study are, in theory, compared fairly. For example, a comparison of external walls may be based on every external wall design in the study achieving a U-value of 0.3 W/m²K and compliance with building regulations.'
Embodied Carbon, The Inventory of Carbon and Energy (ICE), By Prof. Geoffrey Hammond and Craig Jones, Ed. Fiona Lowrie and Peter Tse, published by BSRIA in 2011, defines a functional unit as: ‘A reference unit of study normally used for comparative purposes, e.g. “1 m2 of carpet over a lifetime of 10 years”. A fair functional unit is necessary for such assessments.’
PAS 2080:2023 Carbon management in buildings and infrastructure, second edition, published by The British Standards Institution in March 2023, defines the functional unit as the: ‘…quantified performance of a product or system for use as a reference unit. NOTE The functional unit takes into account a function, a quantity, a duration, and a quality of the asset, network or system being assessed. Refer to the Guidance document for PAS 2080 for further explanation and examples of functional units.’
[edit] Related articles on Designing Buildings
Featured articles and news
Deputy editor of AT, Tim Fraser, discusses the newly formed society with its current chair, Chris Halligan MCIAT.
Barratt Lo-E passivhaus standard homes planned enmasse
With an initial 728 Lo-E homes across two sites and many more planned for the future.
Government urged to uphold Warm Homes commitment
ECA and industry bodies write to Government concerning its 13.2 billion Warm Homes manifesto commitment.
Places of Worship in Britain and Ireland, 1929-1990. Book review.
The emancipation of women in art.
CIOB Construction Manager of the Year 2025
Just one of the winners at the CIOB Awards 2025.
Call for independent National Grenfell oversight mechanism
MHCLG share findings of Building Safety Inquiry in letter to Secretary of State and Minister for Building Safety.
The Architectural Technology Awards
AT Awards now open for this the sixth decade of CIAT.
50th Golden anniversary ECA Edmundson awards
Deadline for submissions Friday 30 May 2025.
The benefits of precast, off-site foundation systems
Top ten benefits of this notable innovation.
Encouraging individuals to take action saving water at home, work, and in their communities.
Takes a community to support mental health and wellbeing
The why of becoming a Mental Health Instructor explained.
Mental health awareness week 13-18 May
The theme is communities, they can provide a sense of belonging, safety, support in hard times, and a sense purpose.
Mental health support on the rise but workers still struggling
CIOB Understanding Mental Health in the Built Environment 2025 shows.
Design and construction material libraries
Material, sample, product or detail libraries a key component of any architectural design practice.
Construction Products Reform Green Paper and Consultation
Still time to respond as consultation closes on 21 May 2025.
Resilient façade systems for smog reduction in Shanghai
A technical approach using computer simulation and analysis of solar radiation, wind patterns, and ventilation.