Top 5 Design Considerations for Complex Refrigerated Processing Facilities
During the last 12 months VHD Studio have been working on complex refrigerated processing facilities. Building Designer, Jordon Waters, shares a glimpse into the five most significant design elements and parameters that need to be considered when working on these projects.
DESIGN CONSIDERATION 1: PIR (polyisocyanurate) Insulated Panel
The use of the PIR insulated panel has become the standard across most of the Australian refrigerated manufacturing scene. Compared to the previous and widely used EPS (expanded polystyrene) insulated panels they can achieve much greater spans between fixings, provide higher insulating properties and are fire resistant. The specification of PIR panels has come with learnings regarding spans, thicknesses, deflections and temperatures.
As one example the required clearances to structural steel elements (columns and beams) can vary due to a number of contributing factors. These may include: the internal vs external temperatures, wind loads and the thickness of panel selected. As a standard we now allow for a minimum 75mm clearance dimension from face of column to PIR panel face from the start of the project. This more often than not will be adequate for any future elements that are introduced including: column base plates. However you can never cover every instance from the beginning and in a recent project the columns housing the diagonal bracing for the portal framed structure had much larger than anticipated base plates and adjustments had to be made during the coordination process.
DESIGN CONSIDERATION 2: Coordination of Services
One of the most important processes to be undertaken in any large scale project these days is the coordination of services. These can include: electrical, plumbing, mechanical or A/C, refrigeration, fire sprinkler systems etc. The most useful tool in a designers belt to assist with this process is BIM (Building Information Modelling). Being able to import each consultant’s design model to ensure there are no clashing elements prior to construction ensures a streamlined construction process and timeline.
The below images show most of the services in one of our projects through the “attic” space and the coordination required to ensure smooth installation for each trade. 
DESIGN CONSIDERATION 3: Condensation
The formation of condensation in and around any building is far from ideal, however when it comes to a refrigerated building that actually helps generate condensation it provides its own set of challenges.
Due to the vast temperature differences between inside and outside of a refrigerated building, consideration has to be given to design options to assist with condensation prevention. One of the biggest issues is in the structure of the building, concrete and steel, which is only amplified the lower the required temperature gets. For example a recent 3900m² freezer and chiller project saw desired temperatures of -25° and -2° respectively. Now comparing that to average summer temperatures in the low to mid 30°s outside, a standard concrete slab would sweat more than a gypsie with a mortgage.
To assist the structural concrete slab in dealing with these large varying temperatures the we tend to suspend them off the ground on large concrete columns and piers. The air movement under the building helps remove the condensation forming on the underside of the slab. The other addition to assist the slab in by having a triple layered floor system: structural slab, PIR insulated panel and a wear slab. By including a PIR panel in the floor system it drastically reduces the temperature transfer through the concrete.
The other culprit mentioned earlier for temperature transfer causing condensation is the structural steel. Typically these buildings use a portal frame system to achieve large spans and therefore large internal spaces. However in some instances the client desired internal space can exceed free spanning portal frames and you end up with mid span supporting columns. These columns can be open to the internal refrigerated temps of the facility, which then carry through the steel into the “attic” space (between PIR ceiling panel and roof structure). Due to mostly being enclosed by roof and wall sheeting there typically isn’t much air movement. However, by providing a large ridge vent as well as keeping a vermin proofed gap between the PIR wall panels and external wall sheeting (refer detail under PIR panel section above), this forces air flow through the attic from a low point up to the ridge vent. Additionally we can wrap the column above the ceiling panel to assist with the temperature transfer and in extreme cases provide a heat trace wire that combats the cold travelling too far up the column.
DESIGN CONSIDERATION 4: Internal windows
The use of internal windows in a food processing facility has certain requirements when it comes to the glass specified due to the hazard of breakage. The initial specification that comes to mind might be a perspex product given that it can’t shatter etc. However, discussions with the client found that cleaning perspex windows in the existing facility tends to scratch the material and hinder the observation of the processing floor. The solution was to specify a double glazed toughened glass product. This avoids the window being able to be scratched etc. while maintaining strength to avoid shattering. The addition of double glazing compared to a single pane was to assist with fogging on the window. Typically these windows are from an office or viewing area that is not refrigerated like the processing areas so there can be varying temperatures on either side of the glass.
DESIGN CONSIDERATION 5: Fire Sprinklers
Another challenge when designing a large building is the class and construction categories it may fall in. If triggering fire sprinklers when designing a refrigerated building is unavoidable then the temperature being maintained internally has an effect on the sprinkler system that can be specified.
The current project in our work flow is a 4500m² processing facility with a typical internal temperature of 5°- 7° meaning that a stand fire sprinkler system is sufficient to provide cover. However if designing a building intended to be a freezer like the previously mentioned 3900m² project, a different approach has to be taken. Due to the such low temperatures a traditional system would end up having frozen water the the pipes and potentially cracked pipes from the expansion. A potential solution would be engaging a fire engineer to assess the viability of a fire starting in a freezer environment.
Our team are experts in designing Industrial Processing Facilities. We are proud to have worked with some of the biggest food manufacturing companies in our region. If you would like to talk further about upgrading current industrial facilities, we would be happy to chat.
All Images by VHD Studio.