In the past few years, Environmental Specialties has undertaken a ‘green initiative’.  This initiative has been to look for, and incorporate, energy efficient elements of environmental chamber design relating to mechanical, electrical, and architectural.  States such as California already require certain design elements by specification, while other states may soon follow with similar design requirements.

Examples of energy efficient design elements are:

-          Hot gas (i.e. three pipe) refrigeration and defrost systems:  ES promotes the three pipe refrigeration system based on using the hot gas of the refrigeration system to provide heating as needed for temperature control and to heat warm rooms.  This is done in lieu of using a two pipe system to overcool the air then electric ‘reheat’ing the air back up to the room condition.  This requires the electricity demand for both the refrigeration system and the electrical heater(s).  A hot gas / three pipe system requires only the electricity for the refrigeration system.  On larger systems, operating 24 hours a day, every day, this translates to $1,000’s of savings in annual operating costs.  ES also promotes hot gas for defrost considering that the refrigeration system electricity is useful in defrosting the coil with only minor supplemental electric heating.  Without hot gas defrost, more electricity is required, and for longer intervals, to provide adequate defrosting.

-          Compressor-to-load matching:  As noted above, ES uses three pipe systems which allows for constant operation (no cycling) and excellent temperature control.  A benefit of three pipe systems is that they are provided with a special compressor pressure regulating valve which limits the suction pressure of a given compressor.  By limiting suction pressure and therefore cooling capacity, the actual compressor capacity, via the valve, can be matched closely to the normal steady state cooling demand of the room.  The lower suction pressure results in lower amperage draw from the compressor, resulting in lower operational costs.

-          PSC and EC evaporator motors:  ES uses primarily PSC (permanent split capacitor) and EC (electronically commutated) motors in the environmental chamber unit coolers.  Both motor types are very energy efficient versus traditional shaded pole motors (EC is the most energy efficient of the two).  Energy efficiency translates into lower electricity demand to the motors, lowering operational cost.  The lower efficiency also translates into lower heat output, reducing cooling system size and ultimately reducing operational cost.

-          Fluorescent and LED lighting:  ES uses modern T-8 fluorescent lamps, energy efficient ballasts, and special 95% back-reflective fixtures for low electricity demand per lumen of light in the room (lumen is unit of visual measure).  The ballasts are also high output, meaning that they drive the T-8 lamps for considerably higher lumen output than traditional ballasts.  ES also uses T-5 fluorescent fixtures in freezers down to -25 C.  This type of fixture is much more efficient than traditional incandescents, generally requiring only 20-30% of the light count with the fluorescents.  LED fixtures are also considered as they offer very low electricity demand per lumen of light output, direct light downward more efficiently into the workspace vs fluorescent, and are provided in color temperatures which provide high visual acuity (i.e. easier to see by).  This can actually translate to lower light count due to the higher visual acuity.  As LED’s become more popular in the lighting market, increased efficiency and lower costs will result.

-          Chilled water cooling:  By using building chilled water for direct cooling of the chamber, or indirect cooling of the refrigeration system, ES can provide simple, energy efficient cooling systems.  Direct cooling chilled water is commonly considered for warm rooms, or those operating at 10 C or higher.  This does not require the electricity demand for an intermediate air cooled refrigeration system; the heat transfer is direct air-to-water.  Chilled water is also used for indirect cooling of the condenser for water cooled refrigeration systems, such that the heat rejection from the refrigeration system is not into the ambient space, thus avoiding the upsizing of the air conditioning system for that space.  This ultimately avoids an increase in the size and operational cost of the space air conditioning system.

-          Foamed panel floors:  Many customers suggest the use of the building concrete floor for cold rooms and, sometimes, freezers.  ES often suggests the consideration of foamed panel floors as it pertains to energy efficiency, electricity demand, and operational costs.  The concrete floor acts as a poor insulator and constant heating source for such cold rooms, and this affects the refrigeration system size and operational costs of such.  An insulated floor, however, is an excellent insulator, allowing smaller refrigeration equipment and lower operational costs.  An insulated floor does carry an initial material and installation cost, but long term payback is relatively quick on larger rooms which generally require very large refrigeration equipment.

-          Custom internal air conditioning (plenum) units:  As we see many requests for external AHU (air handling units), ES recommends consideration of internal air conditioning (plenum) units with the room/chamber space.  Air handling units involve ductwork, often insulated, and the static pressure to move the air over long distances.  This static pressure requires more motor power.  Air handling units also have leak points, as well as the ductwork.  This introduces more cooling demand from incoming warm air leakage.  Both the static and cooling demand increase electricity demand from the system, and operational costs.  ES internal air conditioning (plenum) units avoid the use of external ductwork and the resulting leakage, as well as the static from long duct runs.  Electricity demand and operational costs are reduced.

In recent years, customers have become more and more conscious of the price per square foot of storage space, energy efficiency, and the ease of installation.  As engineering firms have become more involved with environmental chamber purchases, these issues have become critical to the review of options.

When a situation arises where the chamber is small, i.e. a ‘step-in’ chamber less than 8’ x 8’ in footprint, ES recommends consideration of a large reach-in chamber in lieu of the step-in.  For information on both products, refer to the website tabs on walk-in chambers and reach-in chambers.

For a specific comparison, let’s consider the following step-in chamber scenario:

-          Overall size:  7’ wide x 6’-6” deep x 8’-6” high, 4” insulated panels; 345 cu ft interior

-          Left and right wall shelving (usable):  41.5” long x 17.5” deep x 6 tiers spaced at 12”

-          Back wall shelving (usable):  71.5” long x 17.5” deep x 6 tiers spaced at 12”

-          Overall shelving area:  ( 41.5” x 17.5” x 6 ) x 2  +  71.5” x 17.5” x 6 = 16,222 sq in. = 113 sq ft.

Notes:

- Usable shelving is slightly smaller than nominal size due to end posts and shelf edging.

- There is an allowance of approximately 38” width x 48” depth for the user to enter the room and move product into place.

Let’s compare this to a triplewide reach-in chamber:

-          Overall size:  10’-3” wide x 3’ deep x 7’-8” high, 2.5” insulated walls; 114 cu ft interior (usable)

-          Shelving (usable):  116” long x 28” deep x 5 tiers spaced at 12”

-          Overall shelving area:  ( 116” x 28” x 5 ) = 16,240 sq in. = 113 sq ft.

This example shows that a triplewide reach-in chamber, at a nominal 114 cu ft, can provide the same shelf storage area as a step-in chamber, at a nominal 345 cu ft. 

Note that the step-in chamber requires field erection, meaning that site construction and site start-up and testing is required.  The reach-in chamber, on the other hand, is factory assembled, factory tested, then shipped to site. 

Between the two options, the triplewide reach-in chamber is considerably less overall cost (materials and labor), and is a much faster installation (simply unload and roll into the final location).  Both options are energy efficient, but the cost and installation considerations make the triplewide reach-in chamber a highly favorable choice for small to medium volume storage needs.

Environmental Specialties has supplied hundreds of ‘standard’ cold rooms, warm rooms, and freezers over the past 30 years.  While this still represents a large part of the business, a growing part of the business in recent years has included cold cleanrooms and ultra low freezers.  As a Product Engineer, I find these types of rooms most interesting, and a good fit for a company such as ours with depth in engineering and project management resources.

The cold cleanrooms (40 F +/-) are a niche market for environmental chambers companies such as Environmental Specialties, understanding that standard temperature (70 F +/- range) cleanrooms are generally provided by typical cleanroom builders.  Environmental Specialties provides Class 100 to Class 100,000 cleanrooms, with internal stainless steel conditioning units or external air handlers.  Of important note, ES offers the custom internal conditioning units in order to provide a more energy efficient, cost efficient, and space efficient method of cooling and air circulation.  This unique approach has gained popularity over the years with major pharmaceutical companies, using such an approach versus the more traditional (and more expensive) air handler approach.

Ultra-low freezers have been a part of the product line for many years, but have gained more interest in the recent years as biorepository designers have become aware of, and even promote, the revolutionary designs of Environmental Specialties.  Traditional biorepositories rely upon numerous, individual reach-in chambers.  While this is easy to order through a catalog, it is not energy efficient, not cost efficient, and not space efficient.  ES offers multiple solutions for biorepositories, including multiple reach-in units operated by singular (or redundant) cooling systems, multiple chest units operated by similar cooling systems, or the popular walk-in style with multiple ultra-low compartments, operated by similar cooling systems.  The walk-in approach is extremely attractive considering that multiple storage compartments (10, 20, or more) are offered within (1) walk-in system.

Contact the Sales Department at Environmental Specialties to discuss cleanrooms, ultra-low freezers, or any other special design chambers you may require.

Brian Philbeck, PE

Senior Product Engineer