Friday, August 31, 2012

Mechanical Ventilation

Mechanical Ventilation

Mechanical ventilation of your home is a good idea. That means a fan running 24 hours a day 365 days a year. It provides a means of reducing indoor air pollutants and improving IAQ. It’s good for you and your whole family. We have a cute saying “dilution is the solution to indoor air pollution”

But aren’t you supposed to show me ways to save money and use less electricity? I don’t get it

True our goal is to save you money and we will show you how to use less electricity. Remember our goal is to address your safety and comfort and using methods of performance contracting and building science and our end result will be a more efficient home. Even though a fan will be running at all times these fans are very efficient and sip electricity rather than guzzle it. The benefit more than outweighs the cost.

Can’t I just open a window?

Sure you can it’s a good idea to open your windows.  We still want to mechanically ventilate your home to ensure it has fresh air at all times. We want to have control over our fresh air and not simply guess. You can open a window whenever you want but we still need ventilation.

Ok so now we have established you need ventilation. What kind and by what standard. The logical answer would be to use ASHRAE 62.2 2007 here in California s a guideline.  It is what the current California new home construction standard uses. There are some rebate programs that require other versions but we will stick with the referenced code.

Let’s take a 2000 square foot four bedroom home as an example
The formula is pretty basic (sq ft * .01) + (bedrooms + 1 * 7.5)
(2000*.01 =)20 +37.5( =5*7.5)

So we need 57.5 cfm for our home.
So let’s get a 60 cfm fan right? Uuuummmmm probably not

The thing is that we want that amount delivered not close. The type of material used for ducting is important. The length of the run is important. How many elbows does it have is important. Proper sealing of ducts is important. Quality of the product is important.  Not accounting for these factors will have our 60 cfm producing 40 cfm or even less.

I would normally recommend that we take that size and add 15 percent and round up to the next available fan. I would recommend a 70 cfm fan in most cases for proper ventilation.

What about using more cfm would that be better?

Yesnomaybe is the answer.

Yes              It is better for IAQ
No               It is wasting Energy
Maybe       Every home is different and occupants are different. If you have 10 100 gallon fish tanks we might want to ventilate a bit more. There are other reasons as well. We call them when we see them.
For the most part we want to size according to the standards that is why they are there. We want size and install the system correctly and test it to make sure it’s providing you with what you need.

What kind of fan?

This is a good question and the answer can vary given the any different factors.

Balanced system’s which brings fresh air from outside and exhaust stale air from inside. Cost is the biggest issue with this style

Supply only ventilation which brings air from the outside. It puts the home under positive pressure (see does my house suck?) and ensure the air is fresh

Exhaust fans. These are already set up in many homes. The install and parts are more cost effective. However this air will be made up from wherever. Studies have shown that even though there is no control of where the air is pulling from that the air that it pulls in is better than the air in your home. This is the most common strategy not due to performance but due to price.

OK lets seal it tight and ventilate it right!

Thursday, August 30, 2012

Fight Club

Ok its kinda of weird bur recently it seem that I have been in more confrontations then normally happens. OK  I can own it, for those that know me you might not understand but you are not surprised.  It’s just Gallo being Gallo and let’s face it he can’t help it. While I would agree that I am not the smartest guy in the world, however I am not stupid (okay some would disagree) and I will not back down when I think I am right.
Prove me wrong and I will acknowledge with an apology. However if you cannot substantiate expect a response. Normally not pretty.

I have been recently challenged what in my mind is simply mind boggling.  Adhering to an old standard which none in industry would agree with. I protested, I stood by my values. I supported my arguments and I lost. I would surmise that those I protested against are none too happy with me.  

I am moving on.

Next would be a supplier reneging on an agreement for a discount. Take that away without notice and explanation and expect me to agree.  Well once again I would have to say I disagree. I spoke with te harbinger of this bad news. They reviewed my account and changed their position.

You win some and lose some

Thursday, August 23, 2012

Dilution is the solution to Indoor Air Pollution

Cute saying, it rhymes and rings true. Those of us with training in Hers Rating, Performance

Dilution is the solution to Indoor Air Pollution

In Performance Contracting and Building Science have heard this time and again. If we are dozing off in a classroom environment because of the ever so interesting subject of compliance procedures for Energy Star for dealing with an interstitial space in an attic. When the same person for the fifth time asks if he can use visquene to cover this hole and you are past screaming in your head “no shut up you are holding up this ever so interesting class”. The instructor kindly answers that the answer is still no regardless of how many times you ask and how many different ways you ask it, visquene is not solid and that is how I interpret the rule.

The sandman closes in as the gentleman colleague disagrees and continues to expand on the fact that it should be.“Sleep….. you are not in an attic you are in a dimly lit air conditioned classroom” says the sandman “ you do not care about  visquene and interstitial space you want to sleep” and you agree. As gentle sleep folds you in its arms with your head bobbing like a buoy in the ocean while sitting in the classroom in a sea of complete boredom. The instructor then asks how do we handle Indoor pollution “Source Control, dilution” you unwittingly blurt out in an automated response as the rhyme “dilution is the solution to indoor air pollution” dances across your limited consciousness as our gentleman colleague has still not let this visquene point go and expands further.

We do not need to be awake; we do not need to think about it we know this.  What about the average homeowner? How do we convey this information in such a way that they shout from a window “I’ve got indoor air pollution and I’m not going to take it anymore”

How do we get the good word of indoor air quality a subject of conversation? “Well no George I do not have solar but I do have a reduced energy bill due to my source control through air sealing and a continuous use ventilation fan that improves that air I breathe, you should look into it. My house is now cleaner and healthier and I have a reduced energy bill to boot.”

Maybe we need a jingle

ASHRAE 62 point 2 is healthy for us and is good to you shooby  bedooby dooby dooby  doobyity do Call 1800 CLNEAIR for your consultation Today!

put on TV put it on the Radio, publish it in the newspaper, develop the website with cutting edge seo, Have a mass mail campaign, and a full social media assault. WE WILL BUILD AND THEY WILL COME!

Ok bad idea

The answer of course is education and good information. As we move forward in this industry the importance of good information readily being available to the public is important. I think most would agree the good information is out there. Sure we could do better and I am sure we will. The next bit is a bit tricky. How do we get a larger customer base looking for this information? The answer of course is the burden is on us.

Next would be lower cost solutions. Sure we can install an exhaust bath fan at the prescribed rate and pull make up air from wherever at a reasonable cost and is effectively what most customers/builders choose.

I will use a quote I got from a industry partner Dadla Ponzil currently of CCSE. He  calls it air that Contains Ridiculous Amounts of Pollutants or CRAP. It is hard to argue with him as we are uncertain where the air comes from when we exhaust only. Studies would indicate that the air we bring in is of higher quality then the air we exhaust. It would still be nice to know that our fresh air ventilation is actually fresh.

Sure we have balanced ERV and HRV but they are costly. For most homes the uninstalled cost of $ 450-$2000 is pretty big price point I am not saying they are not worth the money merely conveying the objection many have. We can look at supply only and match them with our bath fans in an attempt at a balanced system. But most supply only start at about $ 400 which could hardly be called a savings. We have not added the cost of special switches and ducting.

It  would be nice to have a price point and efficiency  for supply air  something like the whisper quiet fan in the 30 to 80 cfm range to provide fresh supply air into the home. Better yet if it had a point of entry filtration system for easy maintenance. It would seem such a system in combination with an exhaust fan without the recovery could retail less than the current $ 450.00-$2000 of an HRV or ERV for just the parts in the current market.

Saturday, August 18, 2012

Does my house suck?

We are not talking in a slang term when we ask this question. What we want to know is if your home is under negative pressure or is it sucking. This important to know and understand when we look a a house as a system. A house under negative pressure will" suck" air in from a host of unwanted areas increasing the chance infiltration and all the negative attributes that come with it.
This is different than the stack effect but the two interact.
We are most concerned about negative pressure in a tight house. By nature a home that is not sealed well we have less of a risk of being in negative pressure. This is because make up air will be drawn in from whatever penetrations are available (infiltration) there and balance the pressure difference. Our homes can be under negative pressure for a number of reasons.  Wind can push on one side of our home and cause a pressure anomaly on the leeward side.
We are always worried about negative pressure in a tight home. This can cause a negative pressure boundary inside the shell of the home. This can cause back drafting and spillage in natural drafting combustion appliances and could bring dangerous CO gases into living space. These gases can then be trapped having nowhere to go in a well sealed home that remains under negative pressure. Moisture build up is also enhanced and the risk of mold, mildew and durability issues is increased. Sick house syndrome is often attributed to a home under negative pressure. Finding the homes minimum ventilation rate is essential information on a tight home.
We are also worried about mechanical systems in all homes. The average home owner might have the ability to put their home into a negative pressure by running appliances. These include but are not limited to clothes dryer at 200 CFM, bathroom fans at 50 to 150 cfm, central vacuums at 100 to 200 cfm, downdraft ranges, microwave and kitchen exhaust vents of 100 cfm or more. Whole house fans can put our homes under severe negative pressure. A leaky ducting system can cause a home to be under negative pressure. Fireplaces can also put our homes under negative pressure.
So what can we do about it? There are several strategies. First we identify through testing. This would be conducting a CAZ test. 
Our goal is to have the home neutral pressure or ideally just slightly positive. This will keep unwanted infiltration and all the problems that come with it entering our homes. If the home is under too much positive pressure we will waste conditioned air through exfiltration and possibly push contaminates back into our living space.
Understanding our pressure boundaries and establishing them where we want them is crucial for indoor air quality and energy efficiency.

“I don’t get it why would we want to make the house so tight that you would need ventilation?”

I was asked this question by a potential customer. I think that this is certainly valid question. I answered it to the best of my ability within the short amount of time. I explained that the mantra of our industry is to seal it tight and ventilate it right. I explained the positive impact on IAQ and reducing the amount of infiltration from the dirty attic. I said our goal was make the house safe and comfortable and we would naturally become more efficient. That our repairs would work 24 hours a day hot or cold rain or shine.
I explained that the house was already tight and our measures would make it tighter and ventilation was necessary if the work was to be performed. ”but I keep windows open all the time” she replied. I explained that the ventilation would still be needed in case the windows were not open. And that filtered fresh air is a good thing. I explained that this is not a new thing as commercial buildings have been employing ventilation needs for decades. I also explained that current codes here in California have ventilation codes.
“Well I could see it if I had small children but I just don’t see the benefit.”  Our customer base is sometimes willing to listen and sometimes defiant. The fact is that these principals for a performance home are difficult for some folks to accept.  They do not understand nor see the benefit. Nor do they want change.
It is easy for most to grasp the concepts of insulation, duct sealing, windows (as misguided as much of the information is) high efficiency HVAC systems and Photovoltaic’s.  The highest hurdle for most of our customers to understand is Ventilation. The fact that we state we can save you energy and then require a device to be installed that was not currently in the home is counter intuitive. You can’t visibly see stale air or infiltration.
While good ventilation might have the highest positive impact it is in my opinion the hardest concept to sell.