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  1. #14
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    5,991

    Confused VALUED DISCUSSIONS - IAQ - LEARNING

    Quote Originally Posted by shophound View Post
    Fresh air ventilation requirements = Nobody is suggesting not to ventilate with fresh air.

    BOTTOM line: give source control more serious thought when considering ventilation needs.

    The overall challenge for this discussion is to strike a balance between indoor air quality/human health requrements, human comfort requirements, and energy consumption management. The OP built a SIP house with hopes to address the third item - energy management - and got stuck with way too much HVAC capacity, putting his IAQ at risk. He's NOT comfortable and his IAQ levels are NOT good. The building envelope is in his favor, but his mechanical contractor is not. Until HVAC contractors get smarter about building science and heat transfer dynamics in dwellings, this kind of crap will continue happening. It should not. The OP should not have been placed in a posiiton where his above average dwelling design was met with below average mechanical design.
    I ALWAYS APPRECIATE your balanced approaches and discussions.

    What can we hope for in the way of real improvement in IAQ for commerial, institutional and residential buildings ?

    AND How about AIRPLANES to mention the EXTREME!?!

    I guess one may liken it to how well Americans are able to adjust their diets to weight and health control. The learning curve may be measured in Decades instead of years.

    It is in the nature of the human being and spirit to Evolve.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  2. #15
    Join Date
    May 2002
    Location
    Houston Texas
    Posts
    6,308
    Quote Originally Posted by shophound View Post
    A little off-topic for the OP but here goes:

    Formaldehydes and etc. = don't bring stinky stuff into your house if you can help it, but if you can't, let it offgas outside your living space before bringing it into the house (new electronics, fabrics, etc.)

    Try to avoid stinky building materials as much as possible. There are healthier products out there; may cost a little more...your health is worth it.

    Fresh air ventilation requirements = Nobody is suggesting not to ventilate with fresh air. What is being offered is to more closely examine WHY ventilation is required. Human respiration and bodily function is primary, followed by dilution of indoor pollution, which may be best addressed by striking a reasonable balance between source control and ventilation (and supplemental filtration via hepa/carbon methods). An objection to this is that people won't stop bringing or keeping stinky stuff into their home, but how well do they understand what they're breathing when they purchase items that produce strong VOC offgassing?

    If the buying public was more aware of this, and more concerned, mounting pressure upon manufacturers of building materials, furnishings, fabrics, etc. might be enough to convince the manufacturers that the stinky components need to go. You can build a cabinet without putting formaldehyde in it. You can floor a house without spreading out a mat of off-gassing toxic fumes throughout the entire house. And you don't need to douche yourself with gallons of deodorants/perfumes to not smell objectionable to someone else. The way some folk splash on the cologne or perfume, I'd almost rather settle for the odor of sweaty socks...read that ALMOST. Bottom line: give source control more serious thought when considering ventilation needs.

    As for shoulder season ventilation, when little heating or cooling is required, this goes back to my earlier post regarding humidity levels, which is a primary concern when ventilating for any reason. Reducing infiltration of the building envelope not only reduces moisture and heat load gain or loss, it moves the introduction of outdoor air to a controlled source, be it the HVAC system or a ventilating dehumidifier. Some regions of the country, or some residential configurations within any region, may warrant the latter, but for my own dwelling in my own neck of the woods, I can't justify the cost of buying and installing it, when the passive means coupled to my existing mechanical system does the job handily.

    Generally, when I need cooling I need dehumidifying, and when I need heat I may need humidifying, depending on internal moisture generation levels. The house is by no means tight as a drum, but it has enough measures in place to reduce needless air exchange, funneling it down to a controllable level. It is not beyond my means to open a window or two when outdoor conditions permit to allow a really good purging of the interior spaces. This often can happen in "shoulder season weather" with no adverse comfort or IAQ effects. The rest of the time there appears to be enough remaining duct leakage on both supply and return side to assure a sufficient amount of make-up air so the house does not become a locker room.

    The overall challenge for this discussion is to strike a balance between indoor air quality/human health requrements, human comfort requirements, and energy consumption management. The OP built a SIP house with hopes to address the third item - energy management - and got stuck with way too much HVAC capacity, putting his IAQ at risk. He's NOT comfortable and his IAQ levels are NOT good. The building envelope is in his favor, but his mechanical contractor is not. Until HVAC contractors get smarter about building science and heat transfer dynamics in dwellings, this kind of crap will continue happening. It should not. The OP should not have been placed in a posiiton where his above average dwelling design was met with below average mechanical design.
    You and TB have very valid points but when you discuss your home not needing dehumidification unless it needs cooling is fine for Cowtown but is not really true for Houston or the OP's location. You live in a dry climate even more so in the fall and winter. In Houston and along the coast we frequently need supplemental dehumidification much of the year. Just last night it was in the upper 60's but the DP was up around the mid 60's and it was very moist in my house. I had to run the A/C to dry it out and this is a frequent problem from October till early March. This is a common complaint with my customers in all forms of homes from loose to tight.

    Granted TB is a little heavy handed about supplemental dehumidification but we all can be we discussing something we have a passion for. For the OP supplemental dehumidification could be their best option.

  3. #16
    Join Date
    Oct 2004
    Location
    The Zone
    Posts
    392

    I've got an idea !

    We had a Sips home built here in our area by a home inspector who listened to his homes designer. He called us and we found the load below 4 Tons all the other contractors he contacted (a total of 6) wanted 6+ tons, well we went over 4 tons by compromising and talking him into dual stage equipment. Hopefully you could pull your outdoor units and dual stage them to increase your ability to more accurately match your load to the equipments capability. You have to understand during new construction most HVAC contractors are selling HVAC as a commodity and the bigger the unit the greater the profit. Sorry about your problem, hopefully my advice helps.

  4. #17
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,086
    Quote Originally Posted by classical View Post
    You and TB have very valid points but when you discuss your home not needing dehumidification unless it needs cooling is fine for Cowtown but is not really true for Houston or the OP's location. You live in a dry climate even more so in the fall and winter. In Houston and along the coast we frequently need supplemental dehumidification much of the year. Just last night it was in the upper 60's but the DP was up around the mid 60's and it was very moist in my house. I had to run the A/C to dry it out and this is a frequent problem from October till early March. This is a common complaint with my customers in all forms of homes from loose to tight.

    Granted TB is a little heavy handed about supplemental dehumidification but we all can be we discussing something we have a passion for. For the OP supplemental dehumidification could be their best option.
    Classical, I agree with you and see your point. You also saw mine, which I appreciate, which is there's no one "silver bullet" when it comes to IAQ and comfort management. I would be foolish to state that no house needs a ventilating dehumidifier, period. But it's not a panacea, and often it is employed to offset deficiencies in the building envelope and HVAC design/installation.

    Therefore, the opportunity I see for the HVAC contractor is to expand his/her vision from strictly a commodity based model to a value-added approach. Don't just push boxes, sell some intelligence behind that box. Building envelope issues could carry HVAC contractors through those times when the service dispatcher's phone hardly rings. There's no customer base for that, you say? Educate them. If I were in contracting I'd have some source of ongoing info my existing and future customers could refer to, such as IAQ and energy management seminars, online info (a "library" of sorts), etc. I also know from spening several years on this site, and in this section, that there are customers who seek these services and have value-added expectations, but find the going rough, such as our OP. He was sold "value-added" when he went with SIP construction. He wasn't sold "value-added" with his HVAC system. He was "commodityized", if you will.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  5. #18
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,086
    Quote Originally Posted by dan sw fl View Post
    I ALWAYS APPRECIATE your balanced approaches and discussions.

    What can we hope for in the way of real improvement in IAQ for commerial, institutional and residential buildings ?

    AND How about AIRPLANES to mention the EXTREME!?!

    I guess one may liken it to how well Americans are able to adjust their diets to weight and health control. The learning curve may be measured in Decades instead of years.

    It is in the nature of the human being and spirit to Evolve.
    Dan, I appreciate your kind words, and those that follow. You are spot on.

    I've also wanted to tell you that I appreciate your signature line, as follows, particularly the parts I placed in bold:

    "Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities "

    Regarding the nature of our being and spirit to evolve, I could not have said that better. Thank you.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

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