Equilibrium moisture content EMC
Technical paper 35: Moisture measurement in the historic environment, published by Historic Environment Scotland in 2021, defines equilibrium moisture content as: ‘The moisture content at which a material is neither gaining nor losing moisture through exchanges with the ambient environment.’
Equilibrium Moisture Content (EMC) refers to the specific state of a hygroscopic material in relation to its moisture content, and relative to its surrounding environment. It is the point at which the material is neither gaining nor losing moisture and remains in balance or equilibrium with its local environment. The value of the EMC depends on the material being described, as well as the relative humidity and the temperature of its surrounding environment or the air within which it is in contact.
For example, wood is a hygroscopic material, so its moisture levels can rise and fall relative to its local environment. In timber the EMC is most likely to be lower than its Fibre Saturation Point (FSP) which is generally around hen 30%. The exact EMC figure will vary depending on a number of variables which include the type and age of the wood, the area in the cross section of timber and the moisture and temperature of the local environment. For more information see: Fibre saturation point.
This characteristic of hygroscopic materials to help balance moisture and temperature levels can be beneficial to internal environments when left exposed internally.
[edit] Related articles on Designing Buildings
Featured articles and news
The increasing costs of repair and remediation
Highlighted by regulator of social housing, as acceleration plan continues.
Free topic guide on mould in buildings
The new TG 26/2024 published by BSRIA.
Greater control for LAs over private rental selective licensing
A brief explanation of changes with the NRLA response.
Practice costs for architectural technologists
Salary standards and working out what you’re worth.
The Health and Safety Executive at 50
And over 200 years of Operational Safety and Health.
Thermal imaging surveys a brief intro
Thermal Imaging of Buildings; a pocket guide BG 72/2017.
Internally insulating a historical building
An experimental DIY approach using mineral thermal lime plaster.
Tree species selection for green infrastructure: A guide for specifiers.
50 million new trees over 25 years.
Art of Building CIOB photographic competition public vote
The last week to vote for a winner until 10 January 2025.
The future of the Grenfell Tower site
Principles, promises, recommendations and a decision expected in February 2025.
20 years of the Chartered Environmentalist
If not now, when?
Journeys in Industrious England
Thomas Baskerville’s expeditions in the 1600s.
Top 25 Building Safety Wiki articles of 2024
Take a look what most people have been reading about.
Life and death at Highgate Cemetery
Balancing burials and tourism.
The 25 most read articles on DB for 2024
Design portion to procurement route and all between.
The act of preservation may sometimes be futile.
Twas the site before Christmas...
A rhyme for the industry and a thankyou to our supporters.
Plumbing and heating systems in schools
New apprentice pay rates coming into effect in the new year
Addressing the impact of recent national minimum wage changes.