I am working on my first LEED EB project and I am not sure how to meet this pre-requisite. BACKGROUND: My project is a small office building (2000 sq. ft.) located in a 2 story "house" built in 1876. We are replacing the 20 year old HVAC units to help with Energy Efficiency. The recommended replacement has been quoted as two 3 Ton Split units (typical for a residential project).
My question is (1) do these small, basic HVAC units need to be paired with a system like an ERV (Energy Recovery ventilator) which would supply fresh air. One ERV brand says that it can supply whole house ventilation (up to 3500 sq. ft.), but would I have to purchase an ERV for each HVAC system to comply with the Prerequisite? Follow-up question (2) is there another way to comply?
The building is somewhat "leaky" due to its age and inspite of energy conservation measures completed, we probably comply with the required supply of outdoor air, but can't measure or prove!
You rely on LEEDuser. Can we rely on you?
LEEDuser is supported by our premium members, not by advertisers.
Go premium for
David Hubka
Director of OperationsTranswestern Sustainability Services
527 thumbs up
March 7, 2011 - 10:45 am
You do not need an ERV for EA P1 compliance.
If you are mechanically ventilating the space calculate the required fresh air volumes per ASHREA 62.1 section #6. Each of the split systems will most likely be provided with an 8" diameter outside air duct.
If you are naturally ventilating the building follow the requirements of ASHRAE 62.1 section #5.1.
Hope this helps.
Janna Nash
36 thumbs up
March 8, 2011 - 3:56 pm
David,
Thanks! Could you also tell me if measurements can be made just once during the performance period or if they have to be continuous to verify we met the OA flow rate?
David Hubka
Director of OperationsTranswestern Sustainability Services
527 thumbs up
March 9, 2011 - 3:03 pm
Janna,
You'll only need to take the OA measurement once during the performance period. If you provide permanant continous monitoring you may be able to achieve IEQ C1.2 - Outdoor Air Delivery Monitoring.
Janna Nash
36 thumbs up
March 31, 2011 - 5:06 pm
David,
In your response above when you said "You do not need an ERV for EA P1 compliance", did you mean to say IEQ P1? The prerequisite reads outside air intake must meet standard for all normal operating conditions, but what about when the HVAC system is off - like during mild spring or fall weather. That is what made me think we might have to have an ERV system. But I like answer of "no we do not".
Does natural ventilation have to be provided by permanently opened "windows" or could I complete calcuations based on the windows that can be opened by occupants when necessary.
David Hubka
Director of OperationsTranswestern Sustainability Services
527 thumbs up
March 31, 2011 - 5:49 pm
I meant to write IEQ P1, thanks for the clarification.
Even during milder weather days you will still need to provide fresh air in the quatities outlined by ASHRAE 62.1 during occupied hours. On milder days HVAC systems typically operate in the economizer mode.
For natural ventilation systems the wall or roof openings do not need to be permanantly open. They do however require control such that occupants can easily open them when the space is occupied.
Nelina Loiselle
Above Green239 thumbs up
October 30, 2012 - 4:36 pm
I assume for this credit you can also extend your Performance Period back in time...so if I am staring my MR credit preformance periods in a couple months, but I did my ASHRAE 62.1 calcs and had my TAB contractor come and take OA measurments now, it would be ok? I assume then I would just make my PP for this credit start now and end in several months (when the other ones end). Any possible issues with this approach?