At CtrlTech, we combine our experience and expertise with Raised Floor System for 3 decades
A raised access floor, also known as a subfloor or fake floor, is a series of floor panels suspended above the actual floor or ground.
The plenum is the area between the ground/real floor and the raised floor where electrical wiring, fiber-optic cables, and UFAD-based HVAC systems can be installed.
Among other benefits, raised access flooring allows you to maximise floor area and reduce maintenance costs.
This article will discuss how to construct a raised floor over a concrete slab and will include six critical design recommendations and considerations.
The first step is to determine the location of raised access flooring, i.e., the type of structure. While both office buildings and data centres can benefit from increased access levels, this does not mean that their requirements and constraints are comparable.
Similarly, you must be aware of your limitations. For instance, due to inherent height limits, you may be unable to add a full-height access floor during a building retrofit.
Following that, choose if you require full-height access floors or low-profile raised floors.
Floors with Full-Height AccessA full-height access floor is typically 6 to 24 inches above the actual floor/ground, and so provides the most plenum volume. This course is suggested for new-build designs, but it also prepares you to install important building systems such as HVAC.
Raised Access Floors with a Low-Profile
Because the height difference between the raised floor and the real floor is typically 2.5 to 5 inches, it does not provide as much plenum space as full-height floors. It does, however, provide adequate space for electrical equipment and connections. Additionally, it is a viable solution for retrofitting older structures.
As mentioned previously, your choice will be highly dependent on the nature of the design project (new or retrofit) and the building type. For example, a large office building would considerably benefit from UFAD HVAC systems in terms of operational costs, as full-height floors would be required.
Raised access flooring is typically utilised to accommodate the large amount of power and communications wire required for a data centre, as well as a plenum for cooling the cabinets. However, in order to be beneficial for either, it must be sufficiently high. Depending on the size of the data centre and the amount of cooling equipment required, a raised floor should be at least 18 inches high, preferably 24 to 30 inches, to accommodate the necessary wire bundles without inhibiting the huge volumes of air required to cool modern technology. Few structures, unless they are specifically designed as data centres, can accommodate those heights.
Lower levels necessitate specific considerations, such as overhead wire runs or the use of additional, properly situated, smaller air conditioners. Our typical preference is to avoid fake ceilings in order to maximise room height and allow for the installation of cable trays, lighting, and other accessories. However, if inert gas fire suppression is utilised, a ceiling will almost certainly be required to decrease the room's volume and, hence, the amount and cost of the gas. To summarise, there is no single "correct" response to this topic.
Downflow cooling provides an effective "base cooling" platform for the data centre when planned, implemented, and managed properly. Because heated air rises, cooling from below has two advantages: To begin, hot air vented from the back of the equipment rises toward the air conditioners; second, pushing cold air from below can assist in moving heated air away from the equipment's front air intakes. However, this is far from ideal. Cold air also like to fall, making it harder to reach the top of a cabinet, and impediments can prevent warm air from returning to the air conditioners efficiently. Thermally, high ceilings are preferable. However, it is the quality of the design, not the type of design, that determines performance.
Alternatively, overhead cooling can be used. This is the common approach used in office buildings because when the cold air descends from above, it takes up the rising heat on the way down, so maintaining a fairly constant temperature throughout the room. The issue with a data centre is getting cold air where it is needed and keeping it away from warm air so that the air conditioners receive a true return air temperature, which is what determines how much cooling they give. Overhead cooling is best performed through the use of ductwork, which can become quite massive. The option is to send the cold air down the chilly aisles, which complicates the process of returning hot return air to the units, as it wishes to enter from above but must enter through the air conditioners from below.
You do not want the air conditioners drawing in their own cold air through their own returns. It is not only inefficient in terms of energy; it also provides the air conditioner with incorrect temperature information.
To mitigate this issue, some designs utilise the ceiling plenum as the return air path. This has been accomplished through the use of both overhead and under-floor cooling systems. It is possible if the data centre is securely sealed, with no passage through the ceiling to enter or exit the room. However, the heated air must be returned to the air conditioners, which may require additional fans and ductwork that must be coordinated with the overhead cable tray, which is now required if there is no elevated floor.
In short, overhead cooling can become more complex and expensive to design than a well-designed elevated floor, yet it is the only reasonable solution in some buildings. And, of course, when a ceiling grid is built, all flexibility for lighting, cable tray, and duct work placement is lost.
Engineering is a trade-off-based profession. You cannot obtain anything without sacrificing something else. There are no "one-size-fits-all" solutions, although it is widely accepted that the higher the ceiling, the better, and no ceiling is even better. You inquired as to my thoughts. I hope these prove beneficial.
Though we have specified the height ranges for each floor type, you will need to choose one based on the specifications of the building.
For instance, in a data centre, you must ensure that the plenum has the capacity to accommodate the UFAD HVAC system, fiber-optic cables, electrical wiring, as well as flood and disaster protection systems (e.g., earthquake, fire, etc).
However, in a multi-story condominium, you must ensure that the plenum has enough room to accommodate HVAC, wiring, cables, and plumbing. Due to the fact that it affects water management and sewage maintenance, the latter may be subject to local regulatory frameworks.
Finally, you must ensure that the height specification does not conflict with other parts of the building's design (for example, it should not interfere with a load-bearing pillar).
This is why it is vital to define the building's intended use. A typical raised access floor is made up of three primary components: the panel, the stringer, and the pedestal.
You must guarantee that these components can withstand the weight that your end-user may apply to the floor. For instance, if you're constructing a corporate office that won't have any heavy equipment, you might be able to get away with lighter grade flooring components. Industrial locations, on the other hand, will require heavy or extra-heavy grade flooring to support machining systems, vehicles, and other heavy equipment.
Your design choice may also have an effect on the facility's maintainability. In general, a design with a heavy or extra-heavy grade will be more difficult to maintain than one with a low grade.
This relates to part four because it is one of the three primary components of your raised access floor system, but you must chose based on a variety of factors.
To begin, you must check that your panels give the appropriate durability and load bearing for your projects. Additionally, you must guarantee that the panel contains all of the necessary capabilities, such as wiring modules for power outlets and fiber-optic data ports.
Second, because some structures may incorporate the panel as a floor tile, you must consider the panel's finish, design, and quality. A five-star hotel, for example, will require panels made of stone, porcelain, carpet, or other materials.
For Additional Information on Raised Access Floors:
The Complete Guide to Elevated Access Floors
The Benefits of Raised Access Floors: Four Warning Signs That You're Missing the Boat
Five Types of Buildings That Should Utilize Raised Access Floors
Finally, you must adhere to local rules and industry best practises throughout the process of designing a raised access floor. If you're creating a flooring system that will contain plumbing, you're introducing a regulatory hazard - and you must comply.
The second component of this relates to rising industry standards like LEED and WELL. To comply with these guidelines, you must incorporate specified design components into your raised access levels (e.g., specific acoustic requirements).
This article has explained the considerations that must be made while constructing elevated access flooring over concrete. If you're currently designing one, you can consult with turnkey raised access floor integrators to ensure you're making the best choices at each phase.
CtrlTech enables architects to design and execute raised access floors that enable building owners to save money in the long run while increasing the value of their buildings. Utilize our FREE guide to learn how you may benefit from our experience immediately.
Raised floor is a physical construction composed of square-shaped moveable tiles that are supported by height-adjustable pedestals. They form a parallel floor between the room's floor and roof, so creating a service area. Additionally, it is referred to as an Access floor or a Raised Access floor. This type of artificial floor is frequently used in datacenters, server rooms, telecom rooms, and laboratories, among other places. The primary benefit of a raised floor in a data centre is the creation of easily accessible service areas. Raised floor tiles are constructed from a variety of materials, whereas the raised floor pedestal is constructed entirely of galvanised steel. Each pedestal is joined to the surrounding four pedestals via a horizontal metal frame called a stringer, which adds rigidity to the entire construction. Raised flooring systems in datacenters give space for power cable, chilled water piping, refrigerant piping, data cable, and ground wire grid. Most notably, raised floors aid in the dispersion of cold air throughout a data centre equipped with down flow precision air conditioners. Access floors assist in distributing cold air evenly across the room while consuming less energy. The disadvantage of a raised access floor is that it restricts floor loading and makes determining the seismic rating of a datacenter equipped with access flooring difficult. It is always desired for flooring to have a good load bearing capability.
Depending on the use, the type of floor access panel must be chosen. 60 × 60 cm is the standard size of a floor panel. The thickness of the floor panel is adjustable between 28 and 42 mm. Panels can be supplied with a steel galvanised sheet or aluminium foil at the bottom to increase their resistance to excessive humidity.
Different types of flooring systems exist based on the composition of the raised floor tile. In server rooms and datacenters, calcium sulphate and wood core raised flooring systems are frequently used. It is always desirable for floor panels to have a high load bearing capacity, to be incompatible with nature, to be highly fire resistant, to be lightweight, and to be constructed entirely of environmentally benign materials.
As the name implies, Calcium Sulphate (CaSO4) is the primary component. Calcium sulphate or fiber-reinforced calcium sulphate floor panel. At the bottom and top of the core panel, aluminium foil or galvanised steel sheet is given. Due to the inherent features of CaSO4, this type of flooring has superior mechanical and load bearing characteristics. Calcium sulphate is less vulnerable to temperature and humidity changes, making it an ideal material for tiling. Additionally, the galvanised steel strip at the bottom of the tile increases its resilience to humidity and temperature changes. The calcium sulphate raised floor is ideal for datacenters due to its high load bearing ability, fire resistance, and non-combustible nature. This panel is fully environmentally friendly, as it contains no volatile organic compounds.
Access floors with a wood core are used in places with minimal loads and require a modest raised flooring height. Wood core panels provide great dimensional precision, high rolling load performance, and excellent fire resistance at a reasonable cost. The floor panel is constructed entirely of wood clipboards. At the bottom of the panel, aluminium foil or galvanised steel sheet is used to reinforce it against changes in humidity and temperature. Due to the large proportion of wood in this panel, it has excellent antistatic qualities. Due to the ease with which the panel may be cut, it is possible to obtain high dimension accuracy and interchangeability, which is challenging with calcium sulphate floor panels. Because wood core panels are lightweight, they are simple to install and carry. This form of elevated flooring provides cost-effective options with high-quality specifications and features.
LINDNER is a well-known German manufacturer of floor panels. They provide a variety of floor panel options, including LIGNA, NORTEC, VENTEC, and LUMEN. LIGNA is a wood core panel available in thicknesses ranging from 30.5 to 38.5 mm. Nortec is a calcium sulphate panel that is available in thicknesses ranging from 16 to 44 mm. Ventec is a perforated tile with a variable air discharge capacity. LINDNER panels are the highest quality and most reliable on the market. Within its range, the LINDNER panel has a good load bearing capacity. Each panel is equipped with a galvanised steel strip at the bottom to increase the panel's rigidity in areas of high humidity. The panel's edges are timed and altered to facilitate installation. The raised floor panel's covering surface is available in a variety of materials including high pressure limited (HPL), stoneline, woodline, steel sheet, and textile.
Raised access floor systems are utilised in a wide variety of applications that require a significant number of installations. Several examples include the following:
Companies in the banking, insurance, government, corporate, and administrative sectors with advanced computer and/or telecommunications equipment.
Contact centres. Big, open offices necessitate a large number of workstations for computer and telemetric applications.
Processing centres for data. Rooms for the storage and processing of data. They have numerous installations, including acclimatisation, that are channelled beneath the raised access flooring.
Centers for culture and education. In these types of venues, which are specifically created for cultural and educational events, raised access floors are used.
Raised access floor systems incorporate a plenum into which the following installations and services can be routed: electric power, data cabling, telecommunications cabling, air conditioning and acclimatisation, fire detection and suppression, security cabling, and water and drain cabling.
Utilizing a raised access floor enables rapid access to essential utilities for maintenance without requiring disruptive and costly work. The underfloor air distribution system, or "UFAD," is a critical technology.
The following are the critical components of raised access flooring:
Panels: raised access floor horizontal part to step on with a standard dimension of 600x600 mm, although various dimensions can be ordered. There are several types of panels based on their core, which affects their technical qualities. The system panels are available with or without pre-fabricated floor coverings. Discover more.
Pedestals: the structure's vertical component that adjusts in height from 70 to 1500 mm. Discover more.
Stringers: steel rods fastened or clipped to the pedestal head are used to brace the raised access floor tiles horizontally in modules of 600x600 mm.
The most frequently used access floor panels on the market are:
Steel core injected panel: it is made up of two electrowelded steel sheets that are then injected with lightened cement. It can support enormous loads, is fire-resistant and completely waterproof, and offers the best sound absorption.
The chipboard and steel core panel is constructed of a high density chipboard core, a galvanised steel bottom tray, and a top covering. It achieves the highest fire resistance and load resistance ratings. Damp-proofing increases as a result of the usage of galvanised steel.
For raised access flooring, a high load resistance is required.
Classification of fire-resistant materials, fire ratings, and smoke production
Resistant to moisture and humidity
Sustainability of the elevated access floor.
The distinction between steel and aluminium access floor panels is as follows:
The addition of a steel panel bottom tray significantly boosts its capacity for big loads. Steel is a malleable, high-strength material that deforms but does not break. By wrapping aluminium foil around the panel's bottom sheet, you can simply create a broken panel, reducing the panel's load-bearing capacity.
According to UNE-EN 13501, steel has a substantially higher fire classification than aluminium.
Steel safeguards the panel against external aggressors such as dampness, improper use, and grime. Aluminum is easily brittle, exposing the system to external aggressions.
At production centres, a variety of coverings are put to raised floor panels. For example, light floorings like as vinyl, laminate, linoleum, rubber, and carpet, as well as natural coverings like granite, ceramic, and natural wood.
We evaluate the feasibility of installing any new covering that meets our customer's requirements, assuming that it is compatible with our system.
When cold air is pushed into a raised floor, it is anticipated to reach its intended destination, the server racks, but it frequently ends up somewhere else, wasting thousands of dollars in wasted energy each year. According to one study conducted by Innovative Research Inc., this air leakage is largely due to the perforated tiles used in raised floor systems, specifically their placement.
Perforated raised floor tiles are a critical component of an effective raised floor system but are frequently overlooked. All too frequently, owners of raised floors place them arbitrarily in regions that "feel warm," overuse these tiles, or have an insufficient number in their design. Distributed air leakage typically accounts for a significant portion of the overall airflow into the raised floor plenum, and can account for up to 15% of all airflow leaving the data centre room. This not only wastes cooling, but also necessitates the use of more power to cool the equipment.
The authors of the study by Innovative Research Inc. discovered that air leakage is most noticeable in elevated floor systems with a smaller ratio of perforated data centre floor tiles to total floor space, and that fewer perforated tiles actually results in increased air leakage. The company also built a miniature data centre with a 12-inch elevated floor system to do additional study on this subject, measuring air leakage through 4, 8, 12, 16, and 20 perforated tiles. They discovered that four tiles leak nearly twice as much as twenty perforated tiles, and that not all of the airflow exits through the tiles themselves.
Increase the number of perforated tiles in data centres to reduce bypass airflow, provided they are sending cool air to the equipment and all other potential leakage points are closed.
Perforated raised floor tiles are interspersed with solid data centre floor tiles to allow cold air from air conditioners to rise through the floor and cool server racks. Even yet, if raised floor systems are not created properly, air may be forced through other unintended spaces in the floor, causing damage to equipment.
Air can escape through loose cable cutouts beneath cabinets, between computer floor tiles and walls, between misaligned or missing floor tiles, or even through superfluous perforated elevated floor tiles. This is why it is critical to carefully seal any inadvertent openings, such as cable cuttings and edges, and to replace any missing or damaged floor tiles.
Of course, adding perforated computer floor tiles should not be done merely because an area feels warm, and the best method for determining the optimal placement of these tiles is through Computer Fluid Dynamics (CFD) modelling. Insufficient perforated tiles will result in air recirculation, whereas an excessive number will result in increased bypass air.
Because the installation of perforated tiles can significantly improve the energy efficiency of raised floor systems, it's essential to begin with a full CFD analysis that maps out air flow and hot areas and works from there.