All the work and innovation in the draft ASHRAE standard is very much
appreciated!
I must say, the draft seems weak on residential ventilation. It does
require bath and kitchen fans, which is an improvement over the assumption
in the current standard that natural infiltration can provide minimum
ventilation capacity, but not much. I've seen a Canadian study that says
exhaust fans alone don't provide effective ventilation. Shouldn't the
standard take into account what we know--the effects of envelope tightness,
issues like whether or not the installed fans actually work, occupant
controls and on/off time, the effects of ducted forced air and differential
pressurization or providing ventilation through the duct system, and other
practical matters? Compared to the sections on ventilation in commercial
buildings, the residential section seems to have been an afterthought. What
happened?
Mike
>X-Sender: hlevin@mail.cruzio.com
>Date: Fri, 28 Mar 1997 08:35:22 -0800
>To: Marc.J.Rosenbaum@valley.net (Marc J. Rosenbaum)
>From: Hal Levin <hlevin@cruzio.com>
>Subject: Re: GBlist: Demand controlled ventilation
>Cc: "Tom Anderson; Mechanical Systems Design" <hvac@together.net>
>
>Marc:
>
> Since we are (virtual) friends, I will come out right up front and
>tell you that I wrote the design documentation requirements for Std 62-89R.
>I believe that creating the documentation listed there will tremendously
>benefit everyone in the process, save money, and avoid disputes and law
>suits. It will result in more satisfied clients (building owners), better
>indoor air quality, and better system performance. It will allow future
>designers (of tenant improvements or other modifications) to understand what
>the system is designed to do and what it is.
>
> There is lots of attention to the law suits and workers comp claims
>following SBS problems, but there is very little attention to the far more
>common problem of claims between and among design professionals, owners,
>contractors, and tenants. There will be an enormous reduction in the law
>suits and claims by using the required documentation to confirm with the
>client, the contractor, and the TAB and commissioning agents that all that
>is assumed is understood and agreed and that all that is required has been
>accomplished.
>
> I believe the standard is far from being ready to adopt. It will
>require a substantial amount of work. The committee knew that when it put it
>out to public review. We got over 7900 comments to prove it. However, I
>believe that the bulk of the standard does what it is supposed to do and
>should be adopted. I believe it reflects the knowledge in the fields of HVAC
>engineering and indoor air quality in a reasonably balanced way. With the
>exception of Section 6, I believe it is nearly ready to be adopted and that
>all in those in relevant professional fields, trades, and disciplines would
>do well to follow it now. What is in it will become the standard of care
>eventually, and it is only a question of time and to many law suits until
>that becomes more clearly and widely understood.
>
> Section 6 on ventilation rates is complicated. I think it should be
>clarified and refined. The committee is committed to publishing a manual
>concurrently with the adoption of the standard. A spread sheet program
>together with that manual will make what appears complicated in the current
>language far simpler, I am certain.
>
> On the other hand, I do not believe the general approach to
>ventilation rates is any more complicated than the approach used in
>structural engineering for buildings of similarl complexity. If you have a
>simple structure, you look up each members' size in a table in the code. Std
>62 lets you do that for single zone systems too. If you have a complicated
>structural, you have to do some calculation that involves numerous
>considerations. Designing big buildings (over 10,000 to 20,000 sq ft) for
>good indoor air quality and efficient, economical ventilation is not simple.
>Designing very large buildings (over 100,000 sq ft) is very important and
>very difficult. The emphasis is on designing, not just selecting distinct
>items from a catalogue - conceiving of HVAC within a system that includes
>the whole building, its users and the environment. The HVAC system must be
>pretty sophisticated to respond optimally to the almost constant changes in
>demands on it coming from those major system components.
>
> I believe 62-89R looks more complicated than it is. Try downloading
>the spreadsheet from ASHRAE's web site. It will let you see a simple way to
>do deal with systems. The multiple zone problem has never really been dealt
>with adequately from an outdoor air supply requirement perspective. I urge
>you to study it carefully and tell me (and the rest of the committee) if you
>can think of a better way to handle it. I look forward to hearing your
>thoughts.
>
> I have sent a copy of this message to most of the members of the
>committee, since I think your perspective is shared by many folks out there.
>
> Best,
>
> Hal
>
>
>At 08:29 AM 3/28/97 EST, you wrote:
>>I believe the Standard 62-89R that Tom refers to is only a DRAFT - I asked a
>>committee member if he thought it would be adopted by ASHRAE this year and he
>>thought it doubtful. So it doesn't seem to me to be the new "standard of
>>care"
>>just yet.
>>
>>The most useful parts in it for me were the ways to assess how far exhaust
>>components need to be from intake components and windows.
>>
>>I thought the new standard to be overly complicated and unwieldy, and likely
>>that very few engineers who make their living designing these systems day in
>>and day out were on the committee writing them - too complicated. Just check
>>out the requirements for design documentation!
>>
>>Marc
>
>
>
>.-
>
>
>Hal Levin <hlevin@cruzio.com>
>
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