Mass transfer in buildings
The phrase ‘mass transfer’ describes the net movement of mass from one place to another in liquids and gases.
In the simplest interpretation, mass transfer refers to the movement of mass by diffusion at a molecular level. Mass will diffuse from areas of high concentration to areas of low concentration, as described by Fick's law. In this interpretation, the movement of mass by fluid motion (such as convection) is more correctly a part of fluid dynamics rather than mass transfer. That is, mass transfer is dependent on a concentration gradient whereas fluid motion is dependent on a temperature or pressure gradient.
The evaporation of water is an example of simple mass transfer, as the humidity of the air close to the surface of water is higher than that in the surrounding air and so moisture vapour diffuses away from the surface of the water, allowing more water to evaporate.
However, mass transfer is also sometimes taken to refer to fluid flows, driven by temperature and pressure gradients and to phase change.
Mass transfer in buildings is particularly important in cooling processes, such as in cooling towers, chiller units, heat pumps and so on.
Mass transfer is sometimes considered alongside heat transfer, as they are very similar and related processes.
[edit] Related articles on Designing Buildings
Featured articles and news
The Building Safety Forum at the Installershow 2025
With speakers confirmed for 24 June as part of Building Safety Week.
The UK’s largest air pollution campaign.
Future Homes Standard, now includes solar, but what else?
Will the new standard, due to in the Autumn, go far enough in terms of performance ?
BSRIA Briefing: Cleaner Air, Better tomorrow
A look back at issues relating to inside and outside air quality, discussed during the BSRIA briefing in 2023.
Restoring Abbotsford's hothouse
Bringing the writer Walter Scott's garden to life.
Reflections on the spending review with CIAT.
Retired firefighter cycles world to raise Grenfell funds
Leaving on 14 June 2025 Stephen will raise money for youth and schools through the Grenfell Foundation.
Key points for construction at a glance with industry reactions.
Functionality, visibility and sustainability
The simpler approach to specification.
Architects, architecture, buildings, and inspiration in film
The close ties between makers and the movies, with our long list of suggested viewing.
SELECT three-point plan for action issued to MSPs
Call for Scottish regulation, green skills and recognition of electrotechnical industry as part of a manifesto for Scottish Parliamentary elections.
UCEM becomes the University of the Built Environment
Major milestone in its 106-year history, follows recent merger with London School of Architecture (LSE).
Professional practical experience for Architects in training
The long process to transform the nature of education and professional practical experience in the Architecture profession following recent reports.
A people-first approach to retrofit
Moving away from the destructive paradigm of fabric-first.
International Electrician Day, 10 June 2025
Celebrating the role of electrical engineers from André-Marie Amperè, today and for the future.
New guide for clients launched at Houses of Parliament
'There has never been a more important time for clients to step up and ...ask the right questions'
The impact of recycled slate tiles
Innovation across the decades.
EPC changes for existing buildings
Changes and their context as the new RdSAP methodology comes into use from 15 June.