ABX: Reduction by Ventilation

PAYETTE’s Andrea Love and Brian Spangler recently presented “Reduction by Ventilation – Ventilation Inflation!” at the annual ArchitectureBoston Expo (ABX). The presentation was the culmination of a research effort initiated by the firm’s continued commitment to sustainable design practices and Architecture 2030.

Acknowledging that laboratory and health care facilities are the top-consumers of energy against other building types in the building industry, and that a large portion of the total annual energy consumption is attributed to HVAC systems, the research focused on comparing and benchmarking various ventilation methods and outdoor air supply rates in laboratories, office spaces, and patient rooms.

In an effort to better understand the firm’s design trend, an initial step included benchmarking our own work against code-minimum ventilation rates. Assuming that code-minimum ventilation rates will be met, the team then looked for ways of reducing energy consumption through various air delivery methods.

For each of the space types examined, the presentation proposed a 5-step process for designing a ventilation system:
1.    Define space hazards and definitions
2.    Determine applicable codes & standards
3.    Define code minimum
4.    Evaluate air delivery strategies
5.    Select a rate and system

Much of the presentation addressed laboratory spaces, where various airborne hazards and ventilation mechanisms (fume hoods, ventilated cabinets, etc.) create a complex ventilation challenge. Using code-required ventilation rates as the baseline supply rate, the research team used a digital ‘shoebox’ model to compare several air delivery methods including variable air volume, heat recovery, occupancy sensors, demand-controlled, chilled beams and displacement air ventilation.

The team then simulated several combination simulations for each of the space types, by which multiple energy-saving strategies were used in combination.

Patient rooms were included in the digital analysis:

Key conclusions from the research were:
•    Small changes to ventilation rates have a large impact on energy use and operational cost.
•    Selection of the ventilation delivery method has a large effect on energy use, operational cost and occupant comfort.
•    Low energy-consuming ventilation strategies may not be the most cost-effective from an operationally.
•    Define spaces such that areas with high ventilation rates (as required by code) are minimized thereby reducing required ventilation rates and energy consumption dramatically (like separating desk space at the end of a lab bench from the bench area).
•    Select ventilation rates to reflect normal operating conditions – Do not inflate ventilation rates in order to mitigate infrequent hazardous releases.