Laboratory buildings are among the most energy-intensive buildings in Canada, largely because they move large volumes of outdoor air that must be heated, cooled and exhausted. Many were built with constant volume fume hoods, high fixed air change rates and controls that are now obsolete. Retrofitting the airflow controls can reduce energy use substantially while improving safety, because modern systems monitor and alarm conditions older systems never measured.
A lab retrofit is not a simple equipment swap. It touches life-safety systems in occupied research spaces. This guide outlines how to assess, plan, execute and verify the work.
Why retrofit
Common drivers include:
- Energy and carbon. Reducing airflow cuts fan, heating, cooling and reheat energy. Many institutions have carbon targets that make lab buildings a priority.
- Obsolete controls. Older airflow controllers may be unsupported, with no spare parts and proprietary software.
- Safety concerns. Constant volume hoods with no monitors, rooms with unknown pressure direction, and failing exhaust valves are common findings.
- Changing use. Labs converted to computational or dry use may no longer need high airflow.
- Capacity. Reducing lab airflow can free up air handler and plant capacity for new research space without new equipment.
Assessing the existing building
Start with what is actually there and how it performs. A thorough assessment includes:
- Inventory of hoods and exhaust devices: type, size, sash configuration, condition, current flows and certification history.
- Room-by-room airflow survey: measured supply, exhaust, air change rate and pressure direction.
- Controls review: controller types, age, communication, sequences, and whether setpoints match design.
- Hazard review: with the health and safety office, identify what each lab does and what ventilation it needs.
- Air handler and exhaust fan review: capacities, condition, variable speed capability and static pressure.
- Utility and trend data: energy use, operating hours and existing BAS trends.
This often overlaps with retro-commissioning existing buildings and an energy audit, and the findings frequently include low-cost fixes before capital work.
Retrofit measures
| Measure | What it involves | Typical considerations |
|---|---|---|
| Convert hoods to VAV | Add sash sensors, VAV exhaust valve, monitor | Hood suitability, exhaust fan control, room supply must track |
| Replace or add room controls | New supply and exhaust valves and room controller | Space for valves, duct modifications, static pressure |
| Reduce minimum air changes | Lower occupied and unoccupied ACH per risk assessment | Hazard assessment, valve turndown, cooling loads |
| Occupancy-based setback | Occupancy sensors trigger lower minimums | User acceptance, sensor coverage |
| Sash management | Automatic closers or behaviour programs | Obstruction detection, training |
| Exhaust fan optimization | Variable speed, staging, reduced bypass, wind-responsive control | Dispersion study, stack velocity |
| Decouple cooling | Add fan coils or chilled beams for equipment loads | Space, piping, condensation control |
| Exhaust heat recovery | Run-around loops or heat pipes | Corrosive service, frost control, space |
| Demand-based ventilation | Multipoint air quality sensing to vary minimum ACH | Sensor maintenance, safety program acceptance |
Each measure affects others. Lower airflow may make cooling load the governing requirement, which is why decoupling cooling often goes with ventilation reductions. Lower exhaust flow affects stack discharge, which links to exhaust fan control.
Planning and design
Set the performance targets
Before selecting equipment, agree with stakeholders on face velocity targets, minimum air change rates by lab type, offset and pressure requirements, response times and alarm criteria. ANSI/ASSP Z9.5 recommends documenting these in a laboratory ventilation management program.
Check existing infrastructure
New valves need adequate duct pressure and space. Existing ducts may need transitions, and exhaust fans may need variable speed drives. Valve selection must cover the new, lower minimum flows; see air valve sizing and turndown.
Address hood suitability
Not every old hood is a good candidate for VAV conversion. Hoods with poor containment, damaged sashes or obsolete designs may be better replaced. Each hood's containment should be tested after conversion.
Plan the BAS integration
Decide which points the BAS will monitor and how the new airflow system interfaces with existing air handlers and exhaust fans.
Phasing work in occupied labs
Most lab retrofits happen while research continues. Phasing is essential.
- Coordinate with researchers well in advance. Identify experiments that cannot be interrupted and labs that need special handling.
- Work one lab or zone at a time, keeping adjacent spaces at correct pressure.
- Maintain hood exhaust for active hoods or schedule shutdowns when hoods are not in use and chemicals are secured.
- Use temporary controls where needed to keep systems operating during changeover.
- Test each zone before returning it to service, including face velocity, offsets and alarms.
- Communicate clearly with lab users about changes to hood monitors and alarms, and provide training.
Retrofit work in labs often requires coordination with the health and safety office for chemical removal or decontamination of ducts before work starts.
Verifying results
Safety verification
Every converted hood and every retrofitted room should be tested before use: face velocity, response time, containment where required, offsets, pressure direction and alarms. This is a good time to establish baseline data for future fume hood certification.
Energy verification
To confirm savings, follow a measurement and verification plan, often aligned with IPMVP. Measure airflow, fan power and heating and cooling energy before and after. Utility incentive programs in several provinces require M&V for lab retrofits. See measurement and verification of energy savings.
Persistence
Savings can erode as sashes are left open, setpoints are overridden or sensors drift. Trending sash positions, air change rates and offsets, with periodic review, keeps the retrofit performing.
Frequently asked questions
How much can a lab airflow retrofit save?
Savings vary widely with the existing system, climate and measures chosen. A well-planned retrofit that reduces airflow in a cold Canadian climate can be among the most cost-effective energy projects available for a lab building, but estimates should come from a site-specific audit.
Does reducing air changes reduce safety?
Not if it follows a hazard assessment. Fume hoods and local exhaust provide primary protection; general air changes provide dilution. Many institutions have safely reduced minimums with proper assessment and monitoring.
Can we keep the existing valves?
Sometimes. Existing pressure-independent valves can often be reused with new actuators or controllers if they are in good condition and sized appropriately for the new flow range.
Key takeaways
- Lab airflow retrofits can cut energy significantly and improve safety through monitoring and alarms.
- Start with a full assessment of hoods, rooms, controls, hazards and fans.
- Combine measures carefully; reducing ventilation often requires decoupling cooling and adjusting exhaust fans.
- Phase work zone by zone with close coordination with researchers and safety staff.
- Verify safety and savings, then monitor for persistence. Energy audits help prioritize which measures to pursue first.
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