Dedicated Outdoor Air Solutions®

When Venmar CES equipment is configured as a DOAS, energy consumption is significantly reduced (in some cases by up to 35% with certain energy efficient parallel systems) by decoupling the heating, cooling and dehumidification loads of the outdoor air from internal sensible heating and cooling loads of the space. Numerous papers have been written and compiled on the advantages of using these systems over traditional VAV designs.

Regardless of the high performance building standard or guideline, the advantages of using a Dedicated Outdoor Air System can significantly contribute to the success of a high performance building project. Dedicated Outdoor Air Solutions optimize energy performance, allow for increased ventilation and better OA modelling. DOAS can contribute to an improved indoor air quality plan during construction and prior to occupancy. In addition, DOAS can contribute to indoor pollutant and source control objectives, as well as provide better (and simpler) ability to meet requirements for thermal comfort.

Dedicated Outdoor Air Solutions also help to meet indoor air quality best practices in existing buildings, and ensure occupant comfort for the life of the building by supporting a well ventilated and well conditioned space which in turn improves satisfaction and productivity.

LEED BD&C: New Construction Cheat Sheet
Credit Name
Points Requirement Technology
Benefit
EA Credit – Optimize Energy Performance 1–18 Establish energy performance target in the schematic design phase using either of the following options:
Whole-building energy simulation, following criteria in EA Prerequisite – Minimum Energy Performance to demonstrate improvement in proposed building performance compared with baseline.
Implement and document compliance with applicable recommendations in Chapter 4 of the appropriate ASHRAE 50% Advanced Energy Design Guide.
DOAS with energy recovery
Geothermal heat pumps
VFDs
FANWALL TECHNOLOGY®
Reduction in energy costs for building Owner.
EA Credit – Enhanced Refrigeration Management
1
Do not use refrigerants or only use refrigerants with ODP of 0 and a GWP <50.
Or, follow calculation to determine compliance.
Low charge lbs/ton equipment
Consider microchannel
Liquid/solid desiccants
Reduced risk to building Owner.
EA Credit – Advanced Energy Metering 1
Install advanced energy metering for all whole-building energy sources and individual energy end uses representing 10% or more of the total annual building consumption. Packaged controls
Easy monitoring of HVAC equipment performance, either directly or by tying into the BMS.
EQ Credit – Enhanced Indoor Air Quality Strategies
2
Minimum exhaust rates of 0.50 cfm/sq. ft. in areas with hazardous chemicals.
Minimum MERV 13 filtration for each ventilation system.
Increase outdoor air ventilation rates to all occupied spaces by at least 30% above minimum rates, per EQ Prerequisite – Minimum Indoor Air Quality Performance.
Monitor CO2 concentrations within densely occupied spaces.
DOAS with energy recovery
Specify CO2 sensors
Ensures additional outdoor air supplied to space for improved indoor air quality for building occupants and provides integrated CO2 monitoring.
EQ Credit – Construction Indoor Air Quality Management Plan
1
Part of this credit requires the use of MERV 8 filters at each return air grille and return/transfer duct inlet opening during construction. Immediately before occupancy, replace all filtration media with final design media. DOAS with energy recovery
Improves indoor air quality for building occupancy since construction dust and debris entering the AHUs are minimized.
EQ Credit – Thermal Comfort
1 This credit requires design to ASHRAE Standard 55-2010 and verification of occupant thermal comfort. DOAS with energy recovery
Partial load compressor technology
Building occupants are more likely to be comfortable in a space designed to address thermal conditions; building occupants are more productive in a thermally comfortable facility.


LEED O&M: Exiting Buildings Cheat Sheet
Credit Name
Points Requirement Technology
Benefit
WE Credit – Water Metering 2 Establish permanently installed meters – 1 point for two water subsystems, 2 points for four or more water subsystems.
Meters must be recorded weekly and used in regular analysis.
Evaporative condensing
Liquid/solid desiccants
Building Owners will be able to accurately gauge water usage and be able to save money by minimizing excess water usage.
EA Credit – Optimize Energy Performance 20 Earn ENERGY STAR rating above 75, for 3–20 points.
Perform at least 26% better than national average for typical buildings of similar type, for non-ENERGY STAR eligible buildings, for 1–20 points.
DOAS with energy recovery
Geothermal heat pumps
VFDs
FANWALL TECHNOLOGY
Reduction in energy costs for building Owner.
EA Credit – Enhanced Refrigerant Management 1 Do no use refrigerants, or use only refrigerants with ODP of 0 and GWP <50.
Or, follow calculation to determine compliance.
Low charge lbs/ton equipment
Consider microchannel
Liquid/solid desiccants
Reduced risk to building Owner.
EQ Credit – Indoor Air Quality Management Program 2 Develop and implement an IAQ management program based on EPA Indoor Air Quality Building Education and Assessment Model (I-BEAM).
Conduct an I-BEAM audit at least once every five years and revise program as appropriate.
DOAS with energy recovery Ensures delivery of outdoor air and improves indoor air quality for building occupants, reducing risk for building Owner.
EQ Credit – Enhanced Indoor Air Quality Strategies 2 Minimum MERV 13 filtration, regularly maintained and replaced.
CO2 monitors in all densely occupied spaces, with visual alarm if differential CO2 concentration rises more than 15% above minimum outdoor air rate required.
Provide outdoor airflow measurement device (for variable air volume systems) or balance outdoor airflow to design minimum outdoor airflow rate required (for constant volume systems).
DOAS with energy recovery
CO2 sensors
Building occupants are more likely to be comfortable in a space designed to address thermal conditions; building occupants are more productive in a thermally comfortable facility.

Engineering Bulletin

LEED Projects and
Venmar CES

External Links

AEE
ASHRAE
DOE

USGBC