Occupancy for the calculations

Good afternoon,

I have a question about the occupancy I have to take into account for the minimum air flow calculations. For the first review we entered the occupancy defined by the ASHRAE but the response was the following: "3.It appears that the values of occupancy used to define minimum outside air flow requirements via the supporting calculations are the design

occupancies listed in Table 6-1 of ASHRAE 62.1-2007. As indicated on the form, all values of occupancy used to define minimum outside air flow

requirements must be based on the maximum occupancy expected during normal facility operation and not design occupancy, minimum occupancy, or unusual or emergency conditions. According to the Reduced Occupancy Guidance for LEED for Existing Buildings Operations and Maintenance, 2009, the default values for occupancy listed in ASHRAE standard 62.1-2007 should be used only for completely vacant spaces."

We understood that we could not use the occupancy listed in the ASHRAE because it is the minimum occupancy and we need the maximum one. So for the next review we took into account the occupancy defined by the CTE (Spanish building code) that defines the maximum occupancy allowed in each space for some spaces and for the rest the occupancy defined by the owner. And now the response is the following: " ASHRAE Standard 62.1-2007 must be the criteria used instead of the CTE technical code."

What do we have to do? I am very confused. Please help me and thank you very much.

Which calculator version I have to use

I have downloaded the "USGBC LEED 62MZCalc (May 2011) and I have to complete manually the cells that correspondon to the "Inputs of the system". In the "2002UM-62MZ" calculator I do not have to do this because this cells give me automatically an average value of the As, Ps and Vpsd. What I have to do?

I have submitted this prerrequesite with the "2002UM-62MZ" calcualtor and the review team have not told me nothing about the calculator version in the review report, so could I submit with this version?

Besides, Do I have to leave the calculator in "IP" units mode or can I leave it in "SI"? I have submitted it in SI and the review team has not told me nothing about this as well, so I supose I can leave it in SI mode, or not?

Thank you very much.

Occupancy rates

I am not sure why it says on the documentation screen shot that the total occupancy for the VRP calcs should be consistent with occupancy for other credits. For example we have 1,100 full time occupants, but the occupancy for the VRP will be higher because it includes occupancy of rooms such a conference rooms, etc. Where as you might have an occupancy of 79 in a conference room, but there won't actually be 79 people in there at all times.

Ventilation By Exhaust air make-up

We working on a industrial building where there is an unconditioned dining area for factory workers.
This dining area is provided with roof mounted exhaust fans. All exhaust make up is fresh air, that comes through windows and the louvers on the walls. Make up fresh air coming through windows and louvers are well above the ASHRAE minimum ventilation requirements, if make up air flow rate is assumed to be equal to the exhaust air.
However LEED review team says that this won't qualify for mechanical ventilation. Pls note their comment below.
" For spaces that only receive outside air indirectly as a result of makeup air pulled from openings in the building envelope, the project must meet the natural ventilation requirements. Note that the mechanical ventilation compliance path is only applicable to spaces that receive outside air directly from mechanical supply units."

Is this comment correct?
If yes, can we assume the amount of fresh air come through the windows is equal to exhaust air flow rate? or do we have to show the proximity to the windows?
kindly advise..!!

single or multi-zone?

Our building is fully occupied by the same company, so all the floors have similar open space layout, except for enclosed managers or small meeting rooms.

There´s an outside air intake in each AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. level. Each floor is served by one AHU, that provides a mixture of outside air with return air, on a constant volume. There are no VAV´s, no dampers and no different zones in our ventilation plenum.

Since the floors are mostly open space, have no critical zones (bigger meeting rooms, in the last floor, are served by different AHUs), and are all of the same type (office space), is it wrong to consider it a single-zone system, and measure the intakes only in the AHU level? Or should I consider it a multizone and go through all the VRP calculations?

Value input for “Measured outdoor airflow, CFM”

In this prerequisite we are following Case 1 and filling in details in the 2007UM-62MZ Calculator. Further, filling in the online template column 3 in Table IEQp1-2 requires “Measured outdoor airflow, CFM”. I am not able to identify which value has to be input for this column in the 2007UM-62MZ Calculator, which is the cell?
Thank you.

Vacant Space Critical Zones

I am working on a building that has multiple floors that are completely stripped and wide open for new tenants to design the layout to. I am not sure if this is correct but I have calculated out the number of occupants according the to the total floor area and the ASHRAE 62.1 office space standards. As for entering critical zones in I do not know what to do. There are no walls and the whole floor is completely open. I would appreciate any assistance. Thank you.

Adequate measurement equipment and procedures

We are working on an office building with fan-coils units conditioning office spaces on typical floors and several multi-split ceiling cassette units conditioning technical occupied areas (maintenance room, CFTV room and other O&M staff rooms) located on the first underground floor. My questions are:
Can I use a vane anemometer to take measurements in the external air dumper located inside the fan-coil room? Which methodology (sampling, equipment …) can I use to ensure a more precise measurement?
For the underground external air supply, we have a main rectangular duct and several flexible ducts connecting each cassette unit to the main rectangular duct. I need to measure each flexible duct (measurement at each AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork.) or can I measure the total air supplied by the main duct and divide it proportionally to the total air flow of each cassette unit? Which equipment is more adequate for this measurement? I really need make holes in the duct or there is another method less invasive?

The Reference Guide states that measurement at each AHU. However, it doesn’t say which methods or equipment should be used to get a reliable measurement value.

Unknown CFM into spaces

We are using the 62MZ Calculator spreadsheet for an office building. The HVAC system does not utilize VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes or any kind of terminal unit. Rather, it just feeds directly into each space. How do we fill in the CFM (Vdzd) cell for the critical zones? Do we need to calculate it from the space load, measure it, or can we just use a conservative engineering rule of thumb?

Thank you in advance for any help here.

IEQ p1 options

Hi, we are filling the form for the IEQp1 and we have a doubt on what to choose between mechanically ventilated or mechanically conditioned, since we consider our areas mech. ventilated AND mechanically conditioned and the data required is different for each option. Thank you for the help you can provide.

Critical Zone Identification

We are doing a project in which building is of office type and is having 75 AHUs and each AHU is serving one specific tenant area, means there are 75 tenant. Each tenant area is almost 10,000 SF. Building was built as Core and Shell type, and the scope of developer is limited to AHU only ( AHU is located in AHU Room), all other duct work are under tenant scope ( diffuser, grills and inside duct work)

The problem is that building is old and client built up plan is not available and hence there is not any proof of identification of clear division of zones inside the tenant area like conference , private office, pantry etc.

In this scenario, I have these question
1) How can I identify critical zones if Client Built -up Floor Plan is not available?
2) Can I consider the each client area as a single office zone, which means there will be no critical zones analysis?

Ashrae 62.1 vetilation rate - Constant OA with VAV system

We have a constant volume air fan feeding many floors. It feeds the mechanical space using it as a plenum. At the floor level there is a Supply fan serving the VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. and Fan boxes. The floor AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. only has a cooling coil, the heat is provided by reheats. Is it correct to use the maximum cfm for Vdzd and 100% for the Ds? When I use the minimum cfm for this calculation the required OA actually drops.

Mixed use: Production; Shipping/Receiving; R/D; Office Space

The building has four space types and 20 AHUs. The building lacks any integrated controls, so each AHU operates independent of the other. The building has primarily open floor plans, with a few conference rooms and private offices (for 1 person). 20 VRP calculators were completed - one for each AHU, with most AHUs having two zones. The conference rooms are included as a separate zone, as is the cafeteria. Most AHUs serve 6,000 SF or less (some serve only 2,000). The largest AHU serves 25,000 SF.

Our LEED Review comment was "a sufficient number of potentially critical zones have not been identi!ed in the supporting calculations in all cases. Zone level data is used to calculate the required outdoor air at the system level. The documentation must provide sufficient information to show that all potentially critical occupiable zones have been accounted for in the calculations to determine the critical zone. Only a few zones have been
entered in the calculations for each supply air fan. For single air handlers serving over 100,000 square feet, a minimum of 15 zones should
be listed in the VRP calculations for each of the large air handlers. Fewer zones are acceptable for smaller air handlers. Critical zones
generally include conference rooms, training rooms, or other high density spaces with variable occupancy, though office spaces or other
spaces may be the critical zone if the volume of air supplied to the space is limited."

I have a few questions:
1. Do we need to breakout each of the private offices as a separate zone (even though it's not treated as such by the AHUs)?
2. We have 20+ critical zones and have no AHU serving 100k square feet. How would you respond to this comment?
3. Last, we've been treating each of the AHUs as a separate 'system'. Do we need to send over a single calculator, that includes all zones from the smaller AHUs and aggregate all AHU information into one (make-believe) 'system calculator'.?

Thanks
Aaron

62MZ calulator spreadsheet with critical zones

Hello everyone

maybe our first question posted here earlier was not so clear. we just want to know how many critical zones should be put into the spreadsheet with each AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. unit ?? From our understanding , using 62MZ cal spreadsheet and critical zones can be an alternative to calulate the minimum ventilation rate. From 62 MZ cal instructions it provides information on how to define the critical zones in heating or cooling modes. But it does not imply how many critical zones will be enough to put in in each case of AHU calulation ????
for example, one AHU unit serves to total 8 floor plans. For each floor plan there will be critical zones. So should we sum up critical zones from each floor plan and put into the 62MZ cal ? Or should we just use one floor plan as representative one and only count in critical zones from that plan and put into the 62 MZ cal spreadsheet????

we ask these questions here since we tested the 62MZ cal spreadsheet and it felts a bit tricky with inputs for system and inputs for potentially critical zones in the spreadsheet. Even someone suggested here earlier that the input for system can be overriden. Still we want to be sure that we are on the right track.

we really appreciate any advice and hints from anyone who had experience with use of this spreadsheet to earn this credit?

Timing for this Prereq

Need some advice on timing for this Prereq. Would there be any draw back to doing our ASHRAE calcs now for this credit and then having out TAB contractor come and measure OA and make adjustments to OA (as needed to meet ASHRAE per our calcs). We plan do begin our preformance period for our other IEQ and MR credits in several months. But I assume as long as I make my PP for this credit start now and end in several months (when the other ones end) it would be okay?

IEQp1 Design Supply Air Question

Hi,

For the Design total supply to zone (Vdzd) and Design total supply airflow (Vpsd), should those numbers reflect the design flow at the condition analyzed? For example, if I am analyzing ceiling supply heating condition and the zone has a max supply of 250cfm for heating mode and 1,000cfm for cooling mode, which number should I use?

Thanks,

Fresh air requirements for a supermarket

I was wondering if anyone has experience dealing with supermarket fresh air calculations. In particular, is a supermarket's storage area considered an occupiable space? The definition of occupiable space says that storage rooms can be excluded, but has the difference between a storage space and a warehouse space been established at some point in the case of a supermarket?

Thanks

Case 2

If the 62MZ calculator reveals that the critical zone is a zone with cooling only (with a min of 0), is that an appropriate reason to pursue Case 2?

OA damper that closes at certain conditions

We are working on getting an 8-story office building LEED EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. certified. The system utilizes large built up air handlers to provide supply air to fan powered VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. boxes. The system is designed for full economizerAn economizer is a device used to make building systems more energy efficient. Examples include HVAC enthalpy controls, which are based on humidity and temperature. when the ambient air conditions are sufficient. During occupied hours approximately 20% outside air is being provided through the outside air louver most of the time, but when ambient temperatureTemperature of the surrounding air or other medium. (EPA) is below 35 degF and above 85 degF the outside air damper closes because the building cannot maintain temperature set point. We have louver, fan, duct, ect. capacity to meet 62.1 flow rates, but the system cannot maintain set point at the mentioned ambient conditions.

It seems that meeting ASHRAE standard 62.1-2007 is infeasible because of physical constraints limiting the system to provide outside air when outside air is below 35 degF and above 85 degF. Therefore, I assume that we would pursue case 2 and provide 10 cfm of outside air per person. Case 2 states that we need to demonstrate that the current system cannot provide 62.1 outside air flow rates “under any operating condition even when functioning properly”.

My question is since we can provide the required outside air most of the time, does that mean we don’t meet the requirements of case 2 and are out of luck? Thank you for any help that you can provide!

estimating system Ds

Hello All,

I have a building where we are performing calcs on a select number of assumed potential critical zones as opposed to every zone. Regarding estimating and over-riding system Ds (percent of total design airflow at conditioned analyzed), is the following an appropriate strategy considering that I don't have access to the mechanical as-builts?

I will study the furniture plan and come up with a VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. zoning plan using engineering judgement. Based off of that VAV zoning plan, I will determine square feet of "exterior" and square feet of "interior". I will then apply common industry practice and assume a 20% minimum CFM setting for interior zones, a 50% minimum CFM setting for "regular" exterior zones, and a 75% minimum CFM setting for exterior zones with multiple exposures and a lot of glass and/or operable windows/doors (infiltration). The appropriate percentages will then be applied to the appropriate square footages and averaged to get a system Ds.

Does this approach seem like it will suffice for the 62MZ requirement as "sufficient information or backup calculations to confirm that the conditions represent the worst case"?

As always, your help is beyond appreciated.

Exhaust System test for pressurized buildings with no exhaust

Hi all,

We have an existing building built in the early 1900s with three 100% make up air units supplying fresh air with no exhaust. The building is pressurized and fresh air exits through the building envelope. We have taken supply air measurements. What are the EQp1 guidelines for exhaust system tests on pressurized buildings without exhaust fans? There are four small evacuation fans for each bathroom which evacuate less than 5% of the total supply air.

Thank you for your help with this question.

Trending Acceptable for Mins and Maxs?

Once the outside air has been read and the assumed potential critical zones have been identified, if a building owner/staff is unable to compile the mechancial as-builts in order to determine max (Vdzd) and min (used to determine Ds), is it acceptable to trend those spaces through the building DDC system for a certain period of time in order to determine those values? Any further advice? Thanks in advance.

Zone population

Hi all,

I was doing the calculation for my office, and this confused me about the zone population because my office has 2 zones, office zone and conference rooms. Both are served by separate AHUs with separate OA supply.

What should i put in the zone population? Because people cannot occupy the office & conference room at the same time, so is there any ratio i can apply on the total design population?

Thank you,
Billy

Fresh Air Measurements on Rooftop Units

I am applying this credit to ten rooftop units that lack a straight duct section long enough to traverse with a pitot tube. The TAB contractor is concerned that measurements taken at the intake louvers will be inaccurate because of the influence of wind. I envision temporarily fastening some kind of manifold/duct section over the RTU's fresh air intake louver to facilitate measurements. Before I propose this to the TAB contractor has anyone tried anything similar (or simpler) with RTU's? Thanks in advance.

AHU measurements

In our building we have two main AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork. that supply 26 AHU (one for each floor of the building) and then we have VAVs for each zone in each floor.

Do I need to perform measurements just in the two main AHU since this are the ones that have fresh air intake or we need to perform measurements in both the main and secondary AHU?

Thank you in advance

Critcal Zone 100% Out Door Air System

We are currently confusion regarding a review we received. Our building is a multizone building that is supplied with 100% outdoor air. From the review team it is required to perform critical zone calculations even though spaces are supplied with 100% outdoor air. From my understanding critical zone calculations are required for recirculation systems to determine the Primary Outdoor air Fraction (Zp) and System Ventilation Efficiency (Ev).
How can i determine the critical zone for systems with 100% outdoor air supply? Shall I use instead the occupant density and zone distribution configuration (Ez) as the critical figures?
Thanks

Lg AHU serving multiple floors, perform calcs at zone level?

I was brought on to a project to complete the ASHRAE 62.1 calculator after the project was denied LEED EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. IEQp1. The project consists of two high rise office buildings. Tower "A" is conditioned via one air handler per floor with mixed use and occupancy. Tower "B" is conditioned via 4 large air handlers, each serving multiple floors with mixed use and occupancy. I understand after reading through leeduser.com that ventilation readings need only be taken at the air handler at minimum OSA. The owner/F&M staff are having a hard time tracking down the mechanical as-builts which would assist in determining mins and zoning. So, my questions is as follows: am I required to perform the ventilation calcs at the zone level (i.e. determine critical zones such as interior conference rooms)? I just want to be sure that politely demanding as-builts from the client to determine potentially critical zones and the associated mins is appropriate.

Thanks in advance for your help.