Floor Plenum Testing

What is a Floor Plenum Air Test? A floor plenum is a void between a building’s floor structure and a raised access floor. The floor plenum is used for distributing conditioned air to the spaces above. It is important that conditioned air in a floor plenum flows into the occupied zone and does not leak into cavities, risers, stairwells, heating trenches or other adjacent zones.  A properly sealed floor plenum will allow the floor grills and diffusers to fulfil their primary role of delivering air at the correct flow rate. As a result, the air-tightness of floor plenums (or lack of) can be a serious energy efficiency issue and is essential for the whole air conditioning system to work. Testing procedure BG65 / 2016 , addresses these issues and places upper limits on the air leakage of floor plenums. Distinctions are made between air leakage to adjacent spaces - normally referred to as plenum leakage, and uncontrolled air leakage into conditioned zones...

The main terms used in the construction of floor plenums We often get asked many questions regarding the construction of floor plenums.   To try and help our customers we have offered an explanation of the main terms used in floor plenums. Floor Panel – the load bearing, horizontal component of a Raised Access Floor system Floor Pedestal – the vertical, adjustable supporting component of a Raised Access Floor system Subfloor – the existing floor upon which a raised Access Floor System is installed. Plenum wall – the new and/or existing walls to the plenum, that compartments the plenum from the surrounding the other plenum zones. Finished Floor Height – the finished floor height from the subfloor, void height and panel thickness combined. Plenum Void – the space between the underside of a raised floor and the existing sub floor, sometimes referred to as a cavity or plenum. Service penetrations – these are usually ducts or cable trays that penetrate the plenum envel...

Smoke Testing Failed Floor Plenums    A floor plenum is a void between a building’s floor structure and a raised access floor. The floor plenum is used for distributing conditioned air to the spaces above. It is important that conditioned air in a floor plenum flows into the occupied zone and does not leak through air leakage paths in the plenum envelope into cavities, risers, stairwells, heating trenches or other adjacent zones as this may lead to a plenum test failure . Video Showing Smoke Testing of Floor Plenums   If a floor plenum is properly sealed, it will allow the diffusers and floor grilles to fulfil their primary role of delivering air at the correct flow rate. The air tightness of floor plenums can be a serious energy efficiency issue if they suffer excess air leakage.   If the floor plenums fail the test, we can undertake smoke testing to identify the main air leakage paths; however we have to pressurise the plenum to enable us to loc...

What happens if I fail my Floor Plenum Test ? A large number of floor plenums (70-80%) fail the initial air tightness test so don’t panic! If we undertake the floor plenum test and it fails UKAS accredited test engineers will undertake a targeted smoke survey to highlight the main air leakage paths. We will then issue a detailed smoke survey report for your contractors to reference during the remedial sealing works. This will help us the remedial sealing works at they can quickly target the main air leakage paths within the floor plenum construction. We can also undertake thermal imaging surveys to pinpoint the main air leakage paths on the day of the plenum testing . We also allow for the option of visiting site during the sealing works to ensure your contractors are adequately sealing the plenum prior to the second air tightness test. If you would like more information in regards to the most common air leakage paths visit our Plenum Testing website page or call ...

The most common air leakage paths in floor plenums In order to create an effective airtight floor plenum and achieve a successful floor plenum air test, all mechanical and electrical penetrations and perimeter joints must be properly sealed. An evaluation of the following areas/components that can typically create Inefficiencies should be undertaken during the early design phases: 1. All service penetrations through the access floor, walls and sub-floor including:    a. Cable bundles and cable trays    b. Pipes    c. Fire/plenum barriers 2. Cable trunking – must be internally sealed within the void 3. Masonry work - incomplete or poorly jointed masonry walls will result in greater air leakage. All masonry joints must be filled and masonry paint applied as a finish. 4. Risers need to be properly sealed throughout all plenums/ducting need to be sealed. 5. Plasterboard on studs at board edges and the ends below the raised floor...

Constructing Floor Plenums to Pass Air Tightness Testing  There are many considerations when designing and constructing floor plenums to pass the air tightness testing .  In offices, carpet tiles are usually laid over the raised access floor, if joints between carpet tiles are not lined up with the joints between the raised access panel’s floor tiles or panels, the air leakage will be reduced, particularly if the carpet tiles are glued in place. That said, the laying of carpet tiles should not be relied on to achieve the target for the raised access floor itself as these can debond over time resulting in multiple air leakage paths throughout the raised access floor. Many raised access floors include electrical and date boxes. The air leakage of these boxes should be ascertained, to ensure that they will not significantly contribute to the raised access floor leakage, and reduce the air flow to the grills or diffusers. Where there are decorative or functional connect...