You already addressed this credit as part of the compliance process for IEQp1: Minimum Indoor Air Quality Performance. If the measurements you took for IEQp1 indicate that your building has ventilation rates that are at least 30% better than ASHRAE 62.1-2007 for every ventilation distribution system, no further action is required, other than checking that any needed documentation is uploaded.
If, on the other hand, your ventilation rates are not at least 30% better than ASHRAE 62.1-2007, you’ll need to consider whether it is appropriate to pursue this credit.
If you need to increase ventilation rates throughout the building to reach the 30% threshold, you will also be increasing your HVAC energy consumption and associated costs. This may reduce your overall energy efficiency and compromise your compliance with EAp2: Minimum Energy Efficiency Performance and EAc1: Optimize Energy Performance.
However, more fresh air means potential health and productivity benefits. There is debate in the field about whether this tradeoff is worth it. Consider the specific factors in your building in making a decision.
Use the findings of the ASHRAE Level I Walkthrough completed for EAp1: Energy Efficiency Best Management Practices to give you an idea of how much energy is currently being used by the HVAC system. This analysis will help you to estimate the increase in energy consumption that would occur if current ventilation rates were increased.
You may have a good shot at this credit if your building is currently less densely occupied than the scenario for which it was designed (fewer people per space, not empty spaces). Calculated ventilation rates will appear much higher because there are fewer people using the building than the designers expected.
Buildings that use natural ventilation systems can attempt this credit, but the requirements are more challenging. You’ll need to produce design diagrams or analytic models illustrating compliance with the relevant standards. This compliance path is rarely pursued, although that’s due in part to the small number of naturally ventilated buildings going for LEED-EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. certification.
All of the effort for credit compliance occurs during the performance period for this credit.
Before you begin to address this credit, complete all tasks required by IEQp1: Minimum Indoor Air Quality Performance to ensure that your building meets the minimum requirements of ASHRAE 62.1-2007.
If you documented compliance for IEQp1 using the Case 2 compliance path (Projects Unable to Meet ASHRAE Standard 62.1-2007) your building is not eligible for this additional credit.
You might qualify for this credit without any further work. Use the ventilation rate procedure (VRP) calculations that you completed for IEQp1. Check whether outdoor air rates for each ventilation system serving occupied spaces are at least 30% above the minimum amount required by ASHRAE 62.1-2007.
If your building is currently less densely occupied than the scenario for which it was designed (fewer people per space, not empty spaces), you may have a good chance at earning this credit. The ventilation rates will be higher because there are fewer people per square foot, even if your HVAC system is properly sized for the total building area.
If you don’t already comply with this credit (which is usually the case), consider whether it’s worth increasing ventilation rates in order to comply (assuming your HVAC system has the capacity).
Increasing ventilation rates has pros and cons, and no one answer for all projects:
Consider your project’s specific scenario and whether the IAQ benefit outweighs the energy penalty, or vice versa.
Use the findings of the ASHRAE Level I Walkthrough completed for EAp1: Energy Efficiency Best Management Practices to give you an idea of how much energy is currently being used by the HVAC system. This analysis will help you to approximate the increase in energy consumption that would occur if current ventilation rates were increased to at least 30% better than ASHRAE 62.1-2007 as required for the credit.
Increasing the amount of outdoor airflow will increase in the amount of energy required to run your HVAC system, increasing building operating costs.
Increasing the amount of fresh air in your building may also have positive impacts on health and productivity of employees. There have been a number of studies that linked indoor environmental quality with occupant health and productivity—see Resources.
If ventilation rates are not at least 30% better than ASHRAE 62.1-2007, adjust HVAC equipment settings to provide the required amount of outdoor air.
You can increase ventilation rates by adjusting all dampers and louvers in the ventilation system throughout the building. In addition, visually inspect all intake vents and registers and remove any obstructions that restrict outdoor airflow. These activities should also become a part of regular preventive maintenance and ongoing commissioning tasks.
Conduct a second set of airflow measurements and compare these to your original VRP calculations to verify that the outdoor air rate for each ventilation system is at least 30% better than ASHRAE 62.1-2007.
Naturally ventilated buildings can attempt this credit, but the requirements are more challenging. You’ll need to produce design diagrams or analytic models illustrating compliance with the relevant standards. This compliance path is rarely pursued for existing building certifications, due in part to the simple lack of many naturally ventilated buildings pursuing LEED-EBOM certification.
Assess what documentation presently exists that shows the system’s compliance with the natural ventilation criteria. Choose one of the following options to show compliance.
Use diagrams and calculations to show that the design of the natural ventilation system meets the requirements of the CIBSE Applications Manual 10.
Your analysis must address major building factors, including building orientation, to determine exposure to sun and wind; the amount of glazing; internal heat gains; and local weather conditions.
The ventilation strategy must also be assessed for different operational periods throughout the entire day and in each season of the year.
Calculations should note the size of operable windows, trickle vents and louvers, and indicate the effects of both wind and stack-induced pressure differentials on the building’s ventilation and airflow.
Additional costs may be incurred if you need to hire a qualified engineer to perform this assessment. Unless this assessment was performed and documented during the design phase, it’s unlikely that the costs to retroactively perform the assessment are worth pursuit of this credit.
You may also provide the same information required for Option 1 in the format of a macroscopic, multi-zone, analytic model that predicts room-by-room airflow rates.
Follow the modeling guidelines outlined in the LEED Reference Guide and consult with a qualified engineer to meet these requirements.
Several software packages are available to perform these types of computational fluid dynamics models, including AIRPAK and FLOVENT (see Resources).
Your model must indicate the room-by-room airflow rates predicted by the analysis and demonstrate that 90% of the occupied building areas are effectively ventilated by natural means to provide the minimum ventilation rates required by ASHRAE 62.1-2007.
Project teams using this option need to show that ventilation rates are 30% better than the ASHRAE standard. The LEED Reference Guide does not make this clear, but it is a requirement for compliance.
Additional costs may be incurred if you need to buy modeling software or hire a qualified engineer to perform this assessment. Unless this assessment was performed and documented during the design phase of the building, it’s unlikely that the costs to retroactively perform the assessment are worth pursuit of this credit, since it would not generally be feasible to change the natural ventilation system design in an existing building just for the purposes of this credit.
Excerpted from LEED 2009 for Existing Buildings: Operations & Maintenance
To provide additional outdoor air ventilation to improve indoor air quality (IAQIndoor air quality: The quality and attributes of indoor air affecting the health and comfort building occupants. IAQ encompasses available fresh air, contaminant levels, acoustics and noise levels, lighting quality, and other factors.) for improved occupant comfort, well-being and productivity.
Increase outdoor air ventilation rates for all air-handling units serving occupied spacesOccupied Spaces are defined as enclosed spaces that can accommodate human activities. Occupied spaces are further classified as regularly occupied or non-regularly occupied spaces based on the duration of the occupancy, individual or multi-occupant based on the quantity of occupants, and densely or non-densely occupied spaces based upon the concentration of occupants in the space. by at least 30% above the minimum required by ASHRAE Standard 62.1-2007 (with errata but without addenda) as determined by IEQ Prerequisite 1: Minimum Indoor Air Quality Performance. Projects outside the U.S. may use a local equivalent to ASHRAE Standard 62.1-2007 if used in IEQ Prerequisite 1: Minimum Indoor Air Quality Performance.
Projects outside the U.S. may increase breathing zoneThe breathing zone is the region within an occupied space between 3 and 6 feet above the floor and more than 2 feet from walls or fixed air-conditioning equipment. (AHSRAE 62.12007) outdoor air ventilation rates to all occupied spaces by at least 30% above the minimum rates required by Annex B of Comité Européen de Normalisation (CEN) Standard EN 15251: 2007, Indoor environmental input parameters for design and assessment of energy performance of buildings, addressing indoor air quality, thermal environment, lighting and acoustics, determined by IEQ Prerequisite 1, Minimum Indoor Air Quality Performance.
Determine whether natural ventilation is an effective strategy for the project by following the flow diagram process in Figure 2.8 of the Chartered Institution of Building Services Engineers (CIBSE) Applications Manual 10: 2005, Natural Ventilation in Non-domestic Buildings.
Show that the natural ventilation systems design meets the recommendations set forth in the CIBSE manuals appropriate to the project space.
Use CIBSE Applications Manual 10: 2005, Natural Ventilation in Non-domestic Buildings. Projects outside the U.S. may use a local equivalent.
Use CIBSE AM 13:2000, Mixed Mode Ventilation. Projects outside the U.S. may use a local equivalent.
Use a macroscopic, multizone, analytic model to predict that room-by-room airflows will effectively naturally ventilate, defined as providing the minimum ventilation rates required by ASHRAE Standard 62.1-2007 section 6 (with errata but without addenda), at least 90% of occupied spaces. Projects outside the U.S. may use Annex B of Comité Européen de Normalisation (CEN) Standard EN 15251: 2007, or a local equivalent to section 6 of ASHRAE Standard 62.1-2007 to define the minimum ventilation rates.
For mechanically ventilated spaces, design ventilation systems to provide ventilation rates at least 30% above the minimum rates prescribed by the referenced standard. Ensure that the additional ventilation rate does not adversely affect building humidity control during all expected operating conditions.
Use public domain software, such as NIST’s CONTAM, Multizone Modeling Software, along with LoopDA, Natural Ventilation Sizing Tool, to analytically predict room-by-room airflows.
1 Project teams wishing to use ASHRAE approved addenda for the purposes of this prerequisite may do so at their discretion. Addenda must be applied consistently across all LEED credits.
The industry standard on ventilation requirements.
This is a best-practice design guide to natural ventilation.
This spreadsheet categories dozens of specific space types according to how they should be applied under various IEQ credits. This document is essential if you have questions about how various unique space types should be treated.
CONTAM is multizone airflow and contaminant transport analysis software. The software helps determine airflows, contaminant concentrations, and occupants’ exposure to airborne contaminants. The software is available for download here.
One software package available to perform the computational fluid dynamics models required for Case 2 compliance.
Summarizes the factors involved in efficient natural ventilation and provides resources for implementation.
This resource details basic principles and data for HVAC&R design.
This study looks at how increased ventilation rates can improve IAQIndoor air quality: The quality and attributes of indoor air affecting the health and comfort building occupants. IAQ encompasses available fresh air, contaminant levels, acoustics and noise levels, lighting quality, and other factors. and worker productivity.
The following links take you to the public, informational versions of the dynamic LEED Online forms for each EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems.-2009 IEQ credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.
Version 4 forms (newest):
Version 3 forms:
These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictions for these forms; for more information, visit LEED Online and click "Sample Forms Download."
Our project is an office building with 300 regular occupants. One zone/occupancy category of the building is a multi-purpose room. This room is rarely used - only if there are gatherings or occasions. Also, adjacent rooms are cafeteria, fitness room, game room (rooms that occupants are considered transients). And the people that will occupy those spaces will be the same regular occupants of the building, and will definitely not occupy all those spaces simultaneously. How do we account for the population diversity on the required calculation to verify compliance given that for a whole month operation, this space only used twice or thrice and only for three to four hours?
Mary Ann, I think you bring up an excellent point that illustrates the difference between the design ventilation flow required to be available as calculated by ASHRAE 62.1 and how to design a ventilation system to maximize energy efficiency. In short, the ventilation system must be designed such that it can deliver the ASHRAE recommended ventilation when the building is at its peak. The diversity of the building occupants allows you to take credit for the fact that, although the sum room occupants may be one number, the actual building occupants will probably never be that high.
The example I use with other engineers in my office is that if you had a simple office building with 10 offices and a 10 person conference room where no outside visitors were coming in, the diversity would be 50%. You must still calculate each room at maximum occupancy so you will end up with a total occupant number of 20. Since it's only designed to have 10 people 10/20=50%. The other rule that I use when doing a LEED calculation is that I always make sure the number of occupants after diversity is within 10% of the FTE for the project.
As for, the design element, you must make available the full ventilation flow. However, the full flow does not always need to be delivered. That is why we are allowed to utilize demand controlled ventilation in order to turn down the OA and save energy. Let me know if that helps or if you have a more specific question. Thanks.
I input information into their Online spreadsheet, but the numbers didn't seem to match with what our Engineer has as constants for the spaces when the ASHRAE 62 Audit was done. Also some spaces are not defined in LEED Online spreadsheets that our Engineer has in the calculations.
We talked to our Engineer and he said our numbers are more accurate than what LEED Online has.
I tried submitting the open spreadsheet to LEED because we were told by a representative on the phone that this would be acceptable.
We submitted the project, but they wrote in their comments that we need to input the information into their Online Spreadsheet. It seems that there is some sort of disconnect with what is acceptable and what isn't.
Any advice on what I should do upon re-submission?
Richard - You might check out the comment I just posted to EQp1 on this issue but you're in a tight spot with a disconnect between the 62MZCalculator and the LOL table. It sounds like you submitted the 62MZCalculators but did not populate the table because for some reason the table generates a different outcome than the calculator. I think your best bet for resubmittal is to a) double-check the heck out of your calculations to be sure that your 62MZCalculator is right and the LOL table is wrong, and then, assuming that is indeed the case, b) complete the table and provide a detailed explanation as to why the table misrepresents your situation but the 62MZCalc accurately illustrates compliance with the standard. Like I said, its a tough spot to be in during a final review, but I think that ultimately the reviewer can be educated as to your situation and why the calculations don't match.
Hope that helps.
What if my mechanical ventilation was sufficient to meet ASHRAE 62.1 minimums AND the majority of my rooms had operable windows? Could I use the operable windows to meet the 30% additional ventilation for 90% of spaces?
Daniel, I think this would be theoreticaly possible, but fraught with some difficulties. A key one is that your HVAC system is probably designed to operate independently of operable windows, and vice versa. To do what you propose you really need to make sure that they'll play nice together and actually deliver the 30% difference. This may take some complicated work. And is that really how the system will be used?
Principal, Director of Sustainability
Westlake Reed Leskosky
Start off this credit by reviewing your calculations from IEQp1. You may already be in compliance, or you will at least find out what you would need to do to comply.
Integration of permanent airspeed monitoring devices can help to track and maintain ventilation rates.
Building requirements to maintain ventilation rates at a level at least 30% better than ASHRAE should be reflected in your Building Operating Plan and Systems Narrative.
Increases in ventilation rates will have corresponding increases in building energy consumption, which may impact your energy efficiency.
Verification of ventilation rate performance levels should be incorporated into the Commissioning cycle.
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