Physics / Engineering Labs: “Top Five” Energy Efficiency Strategies by Building Type
“Physics” and “Engineering” style labs, though different in their research focus, share many design characteristics. Labs for these disciplines vary wildly in their needs, from “office” type spaces containing only light computing, to highly intensive controlled environment rooms with multiple, expensive mechanical, electrical, and plumbing services. Design requirements could include low structure-borne vibration, low acoustical noise, minimal electromagnetic interference, humidity control, temperature control, and/or filtration of airborne particulates. These labs generally have minimal or no chemical use, few or no fumehoods, and no biological hazards. So laboratory safety ventilation is not a major factor for energy usage. Energy use is driven by the environmental controls, particularly dehumidification and/or particulate filtration.
The most effective EEMs for Physics / Engineering labs are those that target decoupling heating / cooling from ventilation. Also effective is systematic attention to the differences between local environmental controls at the labs vs. building centralized air handling. Use of within-lab fan coils, chilled beams, fan filter units, humidification / dehumidification equipment, and/or specialized “packaged air handling units” (PAHUs) can be highly effective at reducing overall building energy consumption. EEMs that target the building envelope, such as increased airtightness, increased building insulation, reduced glazing, triple glazing, or reduced thermal bridging are important to minimize air quality changes, temperature swings, and humidity irregularities within the research space. EEMs that target lighting efficiency, electrical transformation, and efficient pure water (RODI) and pure lab gas (N2, He, CA) production are also highly effective, as the electrical, water, and gas requirements of these spaces can be extreme.
Our “TOP FIVE” EEMs for Physics / Engineering style labs are:
- Optimize building program distribution
- Space planning for energy efficiency
- Locate high-intensity labs either in basements, or internal to the building, ideally with minimal or no windows
- Optimize building envelope
- Optimized lab envelope is very important for interior environment stability, and thus has an effect on the energy performance of the mechanical systems. This impacts energy demand much more than in a typical “biology lab” setting. Interestingly, “lab envelope” can be a boundary around the room itself, not just the exterior building envelope, requiring unusual provisions, such as air/vapor barriers and/or thermal insulation between interior rooms. Also important is the reversal of relative importance between the various envelope strategies, with minimizing glazing and increased air / vapor tightness being more critical than increased insulation value.
- <40% glazing
- Obsessive detailing to avoid thermal bridging and maximize air tightness
- High R-value walls and roofs
- Separate heating / cooling from fresh air delivery
- Building systems that use high volume delivery of outdoor air to control / temper lab temperature, humidity, or particulates can have significant energy penalties. By separating environmental control from fresh air, much more efficient, localized mechanical systems can be used. (see next strategy for more information)
- Separate lab safety ventilation from lab criteria ventilation
- Labs with tight environmental controls that are also controlled to minimum fresh / outdoor “air change rates” have an enormous inherent energy penalty. We suggest that the team conduct a chemical and biological control band study to determine precise nature of hazards in labs. Work with Environmental Health and Safety (EHS) officers to set lab “air change rates” to minimum possible requirement, based on best knowledge of hazards.
- Similarly, labs with tight environmental controls that also contain fumehoods have an enormous energy penalty. We suggest that the HVAC system decouple fumehood makeup air from general room exhausts. The HVAC system should not rely on the hood being the only exhaust for the space; instead the HVAC system should provide additional room return air registers, valves, and ductwork systems. The architect should specify “low flow” fumehoods, with auto sash closers, small sash openings, and/or “energy awareness systems”.
- Reduce other fresh / outdoor air requirements to minimum (i.e. minimize ventilated enclosures, ventilated chemical storage cabinets, snorkels, etc.).
- Recirculate air as needed for particulate, temperature, and humidity tempering.
- Strategies include: radiant slabs, radiant panels, within-lab fan coils, chilled beams, fan filter units, humidification / dehumidification equipment, and/or specialized “packaged air handling units”
- Demand Control Ventilation
- Use thermostat, humidistat, particulate, and/or Oxygen depletion sensors to control room environmental systems. Do not overdesign and overoperate systems in a “better safe than sorry” high energy mode; instead use sensors to allow HVAC systems to vary in operation with sensed demand.
- Use occupancy sensors to create unoccupied mode for fresh air delivery (maintaining constant temperature and humidity)
- Optimize Mechanical Equipment
- Use central plant resources if available
- High Efficiency boilers, chillers, cooling towers, etc.
- 100% Outside Air Ventilation System
- Enthalpy Wheel AHU
- We note that use of Enthalpy (“Heat”) Wheels in laboratories requires careful consideration. Fumehoods should only be connected to enthalpy wheel AHUs after careful study of the chemical processes to be used in the hoods has determined that cross contamination is highly unlikely.
- Under some circumstances, fumehoods can bypass the enthalpy wheel without significant energy penalty to the overall building systems. Given the relatively low number of fumehoods in these types of labs, this can be effective.
- Airside Economizer
- High efficiency lighting
- Low Ambient / Targeted Task lighting
- Vacancy Sensing
- LED Lighting: some physics and engineering labs have critical electromagnetic interference (EMI) concerns. In these spaces, LED lighting can be important tool to minimize interference, with increased lighting efficiency as a bonus. However, precise selection of LED lighting is very important, since many LEDs contain electronic dimming technology that creates significant EMI.
“GO BEYOND” STRATEGIES
- Geothermal Heat Pump