Modern Houses

[AStudent]

In today's society we shoot for tightness of our houses, the tighter the better, the more efficient. Along with efficiency we also welcome harmful toxins into our homes with no place to escape.

With this said, I ask what is the fine line between too tight of a house, and too loose?

[thermojohn]

This is a good topic... First off, why are you not a pro member? You most certainly qualify at this point. You are missing out on a lot of stuff you could eat up if you could get "in".

[AStudent]

Well....I haven't applied yet. I don't consider myself a "pro".

[jpsmith1cm]

Well....I haven't applied yet. I don't consider myself a "pro".

Doesn't matter if you consider yourself a pro or not.

More technical information is exchanged in the pro sections.

Apply so you can learn more on the other side.

[thermojohn]

Well....I haven't applied yet. I don't consider myself a "pro".

You are a professional when you get your ref cert like you have, and get training like you are getting to better yourself in the trade. A pro also asks the right questions as you seem to do.

I don't like to give away good stuff I have paid for by blood sweat and tears, and $ for anyone to see on an open forum like this. And most other pros here don't either.

Your answers are behind door #3 in the pro section.

[AStudent]

Thanks guys....I'll apply tomorrow...I need to get my student ID from my desk.

I still wanta know about these houses though.

[barbar]

An air tight house is not air tight, it about controlling the air tightness.
So in my neck of the woods, we a have 2 primary systems, "balanced" "HRV" air to air heat exchangers (where fresh air and foul air introduced/extracted equally) preferred by engineers, and positive pressure "PPV", where you force air into the home, and it finds its own way out (uncontrolled) preferred by marketers (bigger claims without need of proof of performance)

[thermojohn]

An air tight house is not air tight, it about controlling the air tightness.
So in my neck of the woods, we a have 2 primary systems, "balanced" "HRV" air to air heat exchangers (where fresh air and foul air introduced/extracted equally) preferred by engineers, and positive pressure "PPV", where you force air into the home, and it finds its own way out (uncontrolled) preferred by marketers (bigger claims without need of proof of performance)

Interesting take on the two types. This is a very in-depth topic that I have a great interest in involving this trade.

Involving balanced HRV/ERV's and tight homes, how do the engineers in your neck of the woods account for the negative pressure encountered by exhaust requirement like clothes dryers, bathroom/kitchen exhausts, etc..?

[barbar]

It was just a few words to help with the basics.
It can be very in-depth and many have different opinions on the how and whys.
So to answer your question, most engineers in NZ tend to higher air change factors (similar to europe) of 50%, so introduction of extract systems has little effect on internal pressure, as difference in countered for with the natural performance changes to the 2 fans in the HRV/ERV unit. Of course a slight loss of efficiency occurs.
Some introduce the extract air back into the the HRV/ERV return, to keep a pressure balance.
Then we consider if we chose a sensible heat exchange system (HRV?), or an enthalpatic system (ERV?) many arguments over this. Much is to do with the various annual conditions different parts of the country have. Where i live we a predominately heating and low moisture content, so Enthalpatic is my choice, to keep dew point somewhat higher. (very few homes here humidify)

[thermojohn]

So I see the argument is at least worldwide. Similar in the states. The area I am in is heavily influenced by Gulf of Mexico moisture, so ERV's instead of HRV's are used, but still the industry is locked between balanced (ERV's) and positive air exchange equipment (ventilating dehumidifiers).

My opinion has moved in the direction of the latter, due to exhaust ducts present for completion of the circuit when the envelope is positively pressurized during required ventilation times.

[air2spare]

So I see the argument is at least worldwide. Similar in the states. The area I am in is heavily influenced by Gulf of Mexico moisture, so ERV's instead of HRV's are used, but still the industry is locked between balanced (ERV's) and positive air exchange equipment (ventilating dehumidifiers).

My opinion has moved in the direction of the latter, due to exhaust ducts present for completion of the circuit when the envelope is positively pressurized during required ventilation times.

dryers and bathroom exhaust are not considered since they are intermittent in use. Positive pressure in provided for when fresh air is brought in for human safety. I think a ventilating dehumidifier thats controlled by humidity and carbon monoixide levels is the way to go.

[barbar]

dryers and bathroom exhaust are not considered since they are intermittent in use. Positive pressure in provided for when fresh air is brought in for human safety. I think a ventilating dehumidifier thats controlled by humidity and carbon monoixide levels is the way to go.

In commercial application, it is now law for new installs (Aus/NZ) that either fresh air make up, is controlled by CO2 or a Heat Exchanger has to be fitted, with an exception of where free cooling is available in the control algorithms.
I think the best choice of any system really does depend upon, the average ambient conditions for each area. So I would not use a simple rule for all areas.
Horses for courses, if you know what I mean.

[RoBoTeq]

The problem is not how well sealed the house is but rather if there is a negative pressure created in the house from exhaust sources such as bathroom/kitchen fans, chimneys/flues or even openings in the ceilings of multi-story houses.

Then there is the problem with the air quality. Dilution is the best solution for air quality. Since there is usually some negative pressure in all houses, combining fresh air makeup with exhaust systems via some sort of heat exchanger is the best way to maintain a healthy home.