Modular laboratories offer a practical solution to energy efficiency and handling dangerous pathogens we encounter today and in the future.
With the recent news about Ebola, MERS, extremely drug-resistant TB and other emerging and re-emerging diseases, the world-wide need for high-containment laboratories is at an all-time high. These laboratories are highly complex buildings that serve as a barrier between the dangerous pathogens handled in the laboratory and the surrounding environment.
The sophisticated heating, ventilation and air-conditioning (HVAC) systems with single-pass air, N+1 redundancies, dedicated electrical connections with backup generators and enhanced security measures make these buildings costly to build and expensive to operate. The majority of performance guidance documents are written in developed countries, while the greatest need is sometimes in remote and underserved areas of the world. This dichotomy has brought the need for modular laboratory buildings as an alternate to attempts at locally engineered and constructed laboratories.
In addition, some parts of the world lack the electrical and mechanical resources required to support a high-containment laboratory. Greater levels of quality control can be achieved when constructing modular laboratories, as they enable complicated construction and testing to be completed in a controlled factory setting prior to delivery. Of equal importance, a modular laboratory allows for the incorporation of unique options for energy savings.
The CDC/NIH Biosafety in Microbiological Biomedical Laboratories (BMBL) defines different levels of containment—from Biosafety Level 1 (BSL-1) for working with materials that pose minimal potential risk of illness, to BSL-4 where the agents pose extremely high risk of illness or death. BSL-3 is suitable for handling moderate risk agents, many of which are prevalent in nature. A BSL-3 laboratory is uniquely suited for studying agents that can be transmitted through the air and cause serious or potentially lethal infection. Historically, BSL-3 laboratories have been constructed as part of a larger building where they are separated from lower BSL laboratories and support space, and surrounded by non-containment spaces. A modular laboratory differs from this traditional model as the laboratory and the support space are contained in a single modular building.
Specialized HVAC systems and air filtration are at the heart of the operation of biocontainment laboratories. They are characterized by high-efficiency particulate air (HEPA) filtered exhaust air and cascades of increasing directional airflow as you move from clean spaces into potentially contaminated laboratory spaces. Conditioned air isn’t recirculated like in a typical HVAC system, meaning the system is forced to cool 100% of the required air from hot, humid outdoor air. To facilitate drawing any airborne pathogens into the building HEPA filter, the rate of airflow per room volume, known as air changes per hour (ACH), is also elevated. The combination of these features is responsible for the containment benefits inherent in these buildings, but they are also responsible for extremely high levels of energy consumption. Traditionally, the air within a BSL-3 laboratory is changed eight to 12 times per hour, but it isn’t uncommon to find the heat load from the equipment within drives the air exchange rate higher. Modular laboratories allow for some unique opportunities to reduce energy consumption while providing the highest levels of containment expected of BSL-3 laboratories.
Recently, two modular laboratories of similar size and function were constructed and deployed in two separate locations around the globe (Southeast Asia and the Caribbean), utilizing similar equipment, and into regions with similar peak HVAC design loads. Both regions were found to have similar peak temperatures and humidity levels, allowing them to be compared as some key energy-saving features were incorporated into the second laboratory. Each BSL-3 laboratory was built into two standard, refrigerated shipping containers, yielding a gross area of 640 sf.
Within each laboratory, the same equipment required for operating a BSL-3 laboratory, such as autoclaves, ultra-low temperature (ULT) freezers, laboratory-grade refrigerators and freezers, were installed. The HVAC design called for single-pass cooling air that’s exhausted without recirculation, which accounts for a significant amount of electrical power. The initial design for the first laboratory called for 158 kW (Table 1).
Since the majority of the electrical load came from the HVAC system, the energy-saving modifications were designed to reduce this load. A number of strategies were implemented, each netting a modest savings of 3 to 5%. These strategies included energy-efficient laboratory equipment and fluorescent tubes, a modified air-handler and an increased internal operational temperature set point (72 F to 75 F). In total, these modifications netted a savings of 25 kW, bringing the overall consumption to 133 kW.
Realizing the autoclave, refrigerator/freezer and ULT freezer were the major sources of heat added to the space, engineers modified the equipment installation to remove heat sources from the laboratory. In doing so, the cooling demand for the space was reduced from a condition requiring 30 ACH to 12 ACH of single-pass air. These modifications netted significant savings on the electrical load, bringing the total demand down to 93 kW (Table 2). The removal of the heat-generating sources netted additional savings of 40 kW. The overall reduction to the HVAC energy requirements was 41%.
By fabricating and attaching stainless steel panels to laboratory equipment, creating a bio-seal between the laboratory and surrounding spaces, the heat-generating elements removed from the laboratory not only reduced heat load, but increased available laboratory space, allowed for maintenance to be conducted in non-contained spaces further reducing labor time/cost and reduced cost associated with personal protective equipment. The initial project placed the entire piece of laboratory equipment and its full heat load within the laboratory environment.
The estimated cost for the energy-saving strategies added approximately $25,000 in cost to the project. The energy saved is estimated to reduce the electrical cost by $8,125/yr, based on an estimated cost of $0.20/kWh on the island where the project is installed. This equates to a ROI in just over three years. With a facility life span of 20 to 30 years, this not only makes for a sound financial investment, it might be the difference in the laboratory remaining operational when in low resource settings. By taking advantage of innovative engineering solutions to reduce energy consumption, the modular BSL-3 laboratory is a practical way to offer a safe environment to handle the dangerous pathogens we encounter today and in the future.