Category Archives: Ventilation

Why The Way your AC is installed Matters! Part I

Screen Shot 2016-06-24 at 8.49.56 AMThe Air Conditioning Contractors of America (ACCA) publishes ANSI Standards for HVAC Contractors to follow. These professional standards are well known in the Home Performance Industry and the HVAC Contractors.  I found a link on their website this morning to a study showing the problems caused with problems that can easily occur if the Industry Professional Standards are not followed.

I covered a study from California about these types of faults recently. This one was completed by NIST.  The National Institute of Standards and Technology, a part of the US Department of Commerce.

CookA quick review of the reports shows many technical details and mathematical formulae.  That forms the back ground for comparisons with other studies.  However, they did write in some plain English for the rest of us. Here is one of their findings, about the performance of heat pumps.

A Heat Pump provides both heat and air conditioning. It is efficient because it moves heat.  In the summer, it moves heat from inside to outside, just like an ac unit.  The same technology and principals. In the winter they move heat from outside to inside. Yes, there is heat outside at cold temperatures.

Think about your refrigerator. When it gets up to around 40° F inside, the unit turns on and finds the heat in that 40° temperature and moves it out of the refrigerator to keep your food cool and fresh. If you watch your temperatures outside, you know more heating is done at 40° and above than at 20°.

This findings for a heat pump cooling your home apply to geothermal heat pumps, regular heat pumps and to air conditioners. They are all working on the same principals.

The first fault they report on is having the wrong size unit.

Changing the size of the heat pump for a given house – either undersizing or oversizing – impacts the heat pump performance in several ways:

  • Cycling losses increase as the unit gets larger; the unit runs for shorter periods and the degraded performance at startup has more impact (parameters used in simulations are: time constant = 45 seconds, or CD ~ 0.15).
  • In the cooling mode, the shorter run periods impact the moisture removal capability (i.e., ability to control indoor humidity levels) because operational steady-state conditions are an even smaller portion of the runtime fraction.
  • In the cooling mode, continuous fan operation with compressor cycling greatly increases moisture evaporation from the cooling coil. However, this impact is minimal with auto fan control (indoor fan time ‘on’ and ‘off’ the same as that of the compressor), since only a small amount of evaporation occurs with the assumed 4 % airflow during the off-cycle with the indoor fan off. If the air conditioner controls include an off-cycle fan delay – that keeps the fan on for 30-90 seconds after the compressor stops – then the impact of off-cycle evaporation is in between these two extremes (Shirey et al., 2006). The results in this study assumed auto fan operation with no fan delay.
  • Heat pump sizing also affects the level of duct losses.

A improperly sized unit will run for shorter periods, and will turn on and off more often. That is just like driving your car around downtown Wichita. Lots of stop lights. Compare you gas mileage to highway driving at a steady speed of 55 mph or higher.

OK, I know efficiency isn’t as important as being comfortable. So the next item is the comfort side.  Running you AC like your car in Down Town, doesn’t remove the humidity as well. Your house temperature is cool, but the humidity is high and you turn down the thermostat again to get rid of the humidity. Pretty soon you are cold, and yet you are not comfortable because you feel the high humidity.  Then you go out and buy a de-humidifier.

The third item is also a comfort issue. That is the advice of many HVAC technicians to set your AC fan to run continuously. When the AC shuts off and the fan keeps running, the humidity the AC just removed from your house is put back in. Oops!

DadBabyESFinally the report mentions duct losses. They are important in a home that has no basement. In those homes ducts can be located in the attic or the crawl space, or both. If you have one of those houses, I would be glad to address that one in the comments. So leave a comment if your are interested.

How do you get a right sized AC unit?   Your HVAC contractor can run a series of calculation found in the professional standard from ACCA Manual J.  It is a Load Calculation.  For cooling it considers the insulation in your home, the windows and size of the home and other details. It can be done on a paper worksheet or a spreadsheet. Both are free from ACCA. Most contractors have a software program to run these Load Calculations.

Load calculations for cooling, are a balancing act. The homeowner wants a home that is cool in the summer and in Wichita, they want the humidity controlled.  Without a lot of formulae or detail, how do, the rest of us, understand a cooling Load Calculation?

My advice is to look at the out door design conditions that must be factored into the calculation.  For cooling, ACCA Manual J has 6 outdoor conditions.

  • Two relate to location. Cooling in Atlanta, is different from Wichita and is different from Denver.
  • One is the outside temperature. The choice is a temperature that covers all but 1% of the hours in a year that require cooling for that location.
  • There are four design conditions that relate to Relative Humidity.

This obviously requires a balance. If your contractor varies from these conditions, it still must balance.  You may or may not like the balance, if one item is changed without consideration of the others.

What should you as a consumer do?

Insist that professional standards be used.

Require that all the items of the standard be measured and reported.

For Air Conditioning the standards require measurements of:

  • Air Flow Actual compared to manufacturer’s requirements. (+/- 15%)
  • Air Flow Static Pressure (ESP)  Actual within the manufacturer’s acceptable range
    • AND
  • No more than 25% or 0.10 IWC over the design pressure for the duct system.
  • Refrigerant Charge Verification
    • Superheat method:  Within +/- 5% of manufacturers superheat value.
    • Sub cooling method: Within =/- 3% of the manufacturers subcooling value.
  • Measured line voltage and low voltage circuits for voltage and amperage. These values shall be within the manufacturer’s requirements.

If you have good air flow in some rooms and not enough air flow in other rooms, your home has an air balancing problem. Have your system checked and balanced. This is known as test and balance or TAB. I have done test and balance work. Generally, the air flows should be within 20% of the design or application requirements.

Medical Study Shows Green Homes Decrease Illness

One of the benefits of buying and living in a green home has always been health related. Energy Efficient and sustainable builders have always taken care to keep water out and to seal up air leaks.  One of the effects is to lower your energy bills. Another is to improve the health of those living in the home.

No Flashing Window

The picture above is a window that was not flashed properly. Water was going into the wall. When you have water and wood together, you get mold.  Many new homes do not have this feature. Remember, there is no legal requirement to install insulation or other healthy features in a home in Wichita or Sedgwick County.

Now, US News and World Report’s Health Day column, written by Amy Norton covers a study in Boston.  She covered the research report in the American Journal of Public Health.

“Researchers found that children living in Boston’s newer, greener public housing had fewer asthma attacks, hospital visits and missed school days, compared with their peers in standard public housing. 

Adults, meanwhile, were less likely to report symptoms consistent with a condition called “sick building syndrome” — which include dizziness, headaches, nausea and eye irritation.”

Buying a home that has green features, such as Water Management Details, Air Sealing, and a Planned Fresh Air system is a big part of the Green Home that creates these benefits. You can find green homes, featuring these benefits, in and around Wichita. Some builder’s choose to have their homes certified to a Voluntary Standard such as Energy Star or Zero Energy Ready or or NAHB Green, or Eco Select.  A certified homes have these features verified by someone other than the builder.

So as the New Home market is growing in the Wichita Area, ask your builder about these features.  Don’t accept the answer that it is not needed, or this is what everyone else does. This is about the health of your family.

Read the entire article

 

Indoor Air Quality – Guideline Revision Public Comments Requested

imagesATLANTA – Public input is being sought into a proposed revision of ASHRAE’s residential indoor air quality guideline.

ASHRAE Guideline 24-2008, Ventilation and Indoor Air Quality in Low-Rise Residential Buildings, is the companion guideline to ANSI/ASHRAE Standard 62.2-2007, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings.  Guideline 24 provides information on achieving good IAQ that goes beyond the requirements contained in Standard 62.2 by providing explanatory and educational material not included in the code-intended standard.

Read Entire Article

 

A New Generation of Smart Sensors Aim to Track the Air You Breathe

AQM bitfinder

HARDWARE STARTUPS WANT TO TELL YOU ABOUT YOUR ENVIRONMENT, IN A WAY YOU CAN ACTUALLY UNDERSTAND.

New gadgets are arriving that are designed to show you in real time just what you’re breathing in, with Internet-enabled indoor and outdoor air-quality sensors.

But one of these devices’ biggest challenges, their makers say, is keeping customers engaged by making sure they understand what the readings mean and how to act on them.

“What we think is really important with this kind of product and services, is that we really need to connect on the human level,” says Ronald Ro, cofounder of Bitfinder.

Having participated in the most recent round of the Internet of Things-focused R/GA Accelerator, Ro’s company plans to release its Awair indoor air-quality monitor this summer. The speaker-sized units will share the market with existing smart indoor-outdoor weather stations from French firm Netatmo, and ultimately with wearable environmental trackers from Vancouver-based TZOA, also slated for release later this year.

The Awair will monitor air temperature and humidity, along with levels of dust particles, carbon dioxide, and a class of chemicals called volatile organic compounds, which includes solvents like acetone and benzene and a range of various other substances of varying toxicity.

(Read More – Take the link below)

I found this article on Fast Company written by Steven Melendez The link will get you to the full story.

WWII and Energy Efficiency of an Office

Enigma-Machine1Occasionally, my long time interest in History and my job intersect.  Here is a news story that does. The headline “Top Secret Documents found in roof at Bletchley Park”, so I naturally read the article.  Bletchley Park during WWII was a great part of the secret  war effort by Great Britain against Germany.  It was run by His Majesty’s Government Code and Cypher School, to read coded German messages. It is named for the landed estate it was located on and has been turned into a museum. Location.  This is about 60 miles or 100 km NE of London center near the M1.

hut 3The connection to Energy Efficiency is these documents were found stuffing into openings in the roof of ‘Hut 3’  The huts were quickly built barracks type structures built early in the war, and did not have many amenities, even for the time.  Things like insulation, central heating, or probably much in the way of wall board on the inside. So these buildings leaked.  I would guess these very smart, talented folks working in Hut 3, didn’t know much about energy efficiency.  They did know when they were uncomfortable and could feel the wind blowing through the cracks and crevices.

So they took what ever was handy and stuffed the cracks full to stop the wind.  Today we call that air sealing.  These are the guys that invented some of the first computing machines. The solution was, like many of the wartime efforts, not the most elegant, but it worked.

If you would like some help locating the air leaks in your home, give me a call. I’ll use a Blower Door and a computer that is a descendant of those in Bletchley Park.

You can read the whole story here.

Indoor Air Quality Evaluations

The quality of the Indoor Air of our homes and offices is an important part of our health and comfort.

There is not much sense in putting a lot of good insulation into a building if it is:

  • Not Structurally Sound
  • Not Healthy

What types of things can be done to improve the Indoor Air Quality of any home or property?

  1. The immediate environment of the structure must be kept separate from the inside.
  2. The required fresh air that is needed, in every one of our buildings, should be filtered and otherwise treated for comfort and to remove pollutants.
  3. The pollutants that are created during the normal operation of our building must be eliminated, removed, replaced, diluted or neutralized.
  4. Moisture in any form must be controlled , and then removed avoiding any accumulation.
  5. Any and all accumulations of moisture damage or animal infestation must be cleaned up and damaged building components replaced.
  • A Full Indoor Air Quality evaluation must address all of those concerns.
  • Full interior visual inspection
  • Full exterior visual inspection
  • Testing of the building enclosure to ensure the outside stays outside
    • Infrared Evaluation as part of the above testing
  • Inspection of HVAC Duct Work and systems that move air.
  • Combustion Safety Inspection on open combustion appliances
    • Moisture, Carbon Monoxide, N02, SO2 and others
  • Infrared and other testing for moisture accumulations.
  • Sample Collection of suspended and/or deposited material that are potential pollutants or irritants.
    • Examination and Evaluation by a certified Microbiological Laboratory of these samples.

This evaluation is typically completed in two visits to the home or business. Level I Evaluation and Testing is non-destructive and not invasive.

Level II Evaluation and Testing involves invasive inspections. These may be as simple as drilling a few holes for visual inspection or sampling. It may involve removing obviously damaged building material, that requires replacement, for example wet drywall.

Contact The Energy Guy for further information about an Indoor Air Quality Evaluation.

Who Is Building an Igloo in Wichita?

It all started on Twitter. @AIAWichita @moongodess316 and I had some fun over building an Igloo.

Igloo1

I saw this Tweet and immediately thought of a quote from Dr. Joseph Lstiburek: “The Igloo was the First Passive House.” Joe is an engineer by training and has been working with buildings, insulation and energy use for over 30 years. His Building Science Corporation, based in Massachusetts, conducts research and is one of the best sources of verified information on building energy efficiency in buildings.

So I tweeted back.

Igloo2

What is the difference between a Passive House and a regular house? What is the buzz all about?

Strawbale

When you build a home you can use lots of insulation to reduce the amount of electricity and gas to heat and cool the home.

GSHP Diagram

You can use a lot of high tech equipment to reduce the amount of electricity and gas to heat and cool the home. You can also do both.

PHIUSThe Passive House was developed in Germany, so you see it referred to at times as Passiv Haus.

We know that insulation works and that more insulation works better. As the cost of electric and gas goes up, it makes financial sense to add insulation to a home or business. In 2000, the local cost of Electricity was 8 – 9 cents, the recommended level of attic insulation was R-30. Today the cost of electricity is 12 – 13 cents and the recommended level of insulation is R-49.  Both have increased about 1/3 in 1 years. We also know that air movement, cold drafts, makes people uncomfortable and causes insulation to not work as effectively.

Round Metal TubeThe sources of air entering a home are usually related to corners. Since we like living in buildings that have square corners there are a lot of them in a home. Windows do not usually cause air leakage. How they are installed can cause air leakage. The age or the quality of the window does not seem to matter when installation mistakes occur.

PHIThe primary requirements for a passive ouse certification are based on Energy Usage and creating a structure that needs very little energy for heating and cooling. These standards are effectively summarized with these two limits.

  • Total primary energy (source energy for electricity, etc.) consumption (primary energy for heating, hot water and electricity) must not be more than 120 kWh/m² per year (37900 btu/ft² per year)
  • The building must not leak more air than 0.6 times the house volume per hour (n50 ≤ 0.6 / hour) at 50 Pa (N/m²) as tested by a blower door.

In our Twitter Conversation, Angee McBustee tweeted a question about how is building a igloo in Wichita. Then I responded with the offer to run the blower door test. As you can see from the primary requirements the Blower Door result is very important to a passive house.

Igloo4

How good is a Blower Door Test of 0.6, as required by Passive House? Energy Star New Homes require a Blower Door Test of 5.0 or less. New homes in Wichita routinely test around 4.0. In the blower door testing, lower is better.

For standard construction, I have tested several homes at 1.0. There is one home that I have tested with a lower result. A custom home in Butler County is under construction. They had me do a Blower Door test after it was sheathed. No insulation, no drywall. The test result was 0.62. We were able to find several leaks using biometrics and the infrared camera. That was last September. I returned in December to test it a 2nd time, the results were so low, that I didn’t have the right test equipment to measure the result. I would estimate it to be in the 0.30 range. I now have the equipment to test a home like that.

In February, I have been accepted for training and certification as a Passive House Rater/Verifier. Christine is building the home in Butler County, I want to thank her for the push to obtain this certification.

In the Twitter Conversation, AIA Wichita came back and said they were posting an information tweet.

Thanks to Angee and AIA Wichita for a nice idea for a Blog Post.

Passive House Work in Wichita

In the last two weeks, two national groups that certify construction for Passive House Standards conducted their annual conferences.  PHIUS was held in Portland, OR; and PHI was held in Maine. Locally, I have completed the first of 3 planned Blower Door tests for a passive concept home under construction; discussed the planned construction with another builder to start later this year; and discussed passive building concepts with another builder planning his first homes next year.

PassivhausDarmstadtKranichstein-300The Passive House concept started in Germany, with construction starting in 1990 on several homes. In German, it is Passiv Haus,  PHI for Passiv Haus Institute.  The standards followed by this concept require an attention to detail in design and construction of the thermal enclosure.  Historically referred to as the envelope, the thermal enclosure involves the exterior bottom, sides and top of the structure.

  • Higher than commonly used levels of insulating material,
  • windows meeting specific standards and very
  • Effective work on air sealing
  • Attention to the Solar Orientation of the home to maximize the use of solar heat in the winter

PHIThis results in an extremely low energy bill.  How low? In the Wichita area, this would translate to an $88 – $110 annual natural gas bill, instead of $500 – $900 bills that I routinely see on Home Energy Audits.

The passive term comes from the idea of using insulation and construction techniques to create a significant energy savings instead of relying on fancy machinery to create that savings. Dr. Wolfgang Feist of Dahrmstat, Germany founded the Passiv Haus Institut in 1996.

Smith HouseThe passive house concept arrived in the US in 2003.  Katrin Klingenberg, a licensed architect in Germany, She built a home meeting these standards, 2 hours south of Chicago.

 

Most countries have a local organization that trains and certifies homes and commercial buildings to the Passive Standard. Yes, passive concepts apply to buildings other than homes. These groups train people to apply and measure the standards. They also review the reports on specific buildings and accept or deny actual certification for a specific building.

PHIUSIn the US, this organization has been known as PHIUS.  Passive House Institute, US. Ms Klingenberg has been the leading light of this group, which was founded in 2007.  There are some things in each country that differ from the original German model of Passiv Haus.

The experience of the professionals working with PHIUS in the US has resulted in some changes to how the concept is applied in the US. For example, the metric units used in the German (and most others in the world) have been translated to the Imperial units used in the US. The collaborative nature of US business groups has been essential to moving the passive concept from being used by a relative few to becoming a market force in the US.

Because these adaptations by PHIUS to the US market, were not acceptable to the original PHI, a divide between the approaches has occurred in the US.  It is mostly technical, and both groups agree the concept is still primary.  Effective building resulting in low energy use.

Some claims have been made that these concepts are two expensive for the US market. The original Passive House in Illinois was built at a 2003 cost of $94/ sf.  That is very favorable with current US construction costs. Since additional people are using the concept and the resulting products that manufacturers are producing, the mass production will bring some drop in costs.

If you wish to read more about the two national conferences for both the PHI and the PHIUS organizations that just finished, you may use these articles.

The 9th annual North American Passive House Conference (PHIUS)

Report from the Passive House Conference in Maine

I will keep you updated on activity in this area about Passive House building activity, as it progresses.  Three projects is a great start.  I’m glad that builders are willing to try new concepts and that home buyers are willing to step up and buy these homes.

In the introduction of this post, I mentioned a house under construction with the Passive House concept. I conducted the first of 3 Blower Door Tests last week.  This test was after the framing and exterior sheathing was completed.  Insulation, plumbing, electrical and trades had not started.  The second test will be in a few weeks after these trades have done their initial work and put holes in the enclosure.  Electric wires, plumbing, HVAC and other necessary conveniences of our lives will be installed in passive concept homes. The third test will be done at the end of construction.

The PHI/PHIUS standard for Air Infiltration as measured by the Blower Door Test is 0.60 –  The current 2012 recommended code requirement for this is 3.0 — Wichita/Sedgwick County does not have an energy code in place, but the Kansas City area does. They enforce a 5.0 standard.  Typical homes built from 1980 and prior are in a range of 10 – 38 from my testing.

The goal of the builder on this passive concept home was to reach 1.5 on this first test. Then using the Infrared Camera to find areas to caulk, and fixing the penetrations mentioned above, have the next test come in lower.

Blower Door62This test, actually came in at 0.62 —  almost the standard.  Much better than the expected 1.5 .   While the blower door was running, the Infrared found some places that could be fixed.  Dan, the carpenter, was right there with a caulking gun.  We also found some leakage with biometrics. A back of your hand that is wet, will show you extremely small amounts of air movement.  Most builders like to use expanding foam to seal the actual window to the rough opening.  We found some of these foamed openings were still leaking. Again the caulking gun was a good answer.

 

A Healthy Home Part 4 – Free of Combustion By-Products

This post is written as a conversation between a homeowner and myself as it could have occurred during a Home Energy Audit. It is actually the gathering together of several conversations on different audits over the past few years.

smoky fires

 

A Healthy Home is Free of Combustion By-Products

Homeowner: Oh!  You mean no Carbon Monoxide!  I have a  Carbon Monoxide Detector.  It has had some false alarms, but it has never found a problem.

The Energy Guy: OK!  Carbon Monoxide (CO) is one by product of combustion.  There are others.

Homeowner:   So, you mean the house must be all electric?

The Energy Guy: No, not necessarily.  An all electric home, might have a fire place, and an attached garage. Both are sources of CO and other byproducts of combustion. A healthy home will deal with all of these in some fashion.

Homeowner: What other things are you talking about besides CO?

rustDHWThe Energy Guy: The one I see the most of is moisture.  Many of the flue pipes I’ve seen have rusted from the moisture.  If you have a gas hot water heater, look at the top.  Is the top rusting, what about the flue pipe or the draft diverter? Moisture from open combustion appliances also increases the humidity in the home and adds unneeded work to your air conditioning unit, increasing the bill.

There are others, such as Nitrogen  Dioxide, and Sulphur Dioxide, and various particles of all sorts.

Homeowner:  So, those are like Carbon Dioxide?  Something that is just there?

The Energy Guy:  Yes!  They are just there, with two concerns.  First the Lung Association points out the health effects of Sulphur Dioxide include:

  • Wheezing, shortness of breath and chest tightness and other problems, especially during exercise or physical activity.
  • Continued exposure at high levels increases respiratory symptoms and reduces the ability of the lungs to function.
  • Short exposures to peak levels of SO2 in the air can make it difficult for people with asthma to breathe when they are active outdoors.

Health effects of Nitrogen dioxide include:

  • Increased inflammation of the airways
  • Worsened cough and wheezing
  • Reduced lung function
  • Increased asthma attacks
  • Greater likelihood of emergency department and hospital admissions
  • Increased susceptibility to respiratory infection, such as influenza

Homeowner: I’m pretty healthy, but you said ‘First!’

The Energy Guy:  The second is moisture. Moisture could be a high humidity situation, or moisture from the combustion that produced these dioxides and if you inhale some of them, or moisture in your nose and lungs. Here are the basic chemical equations for those interested.

Sulphur Dioxide plus Water ends up as Sulphuric Acid [SO2 + H20 ===> H2SO3 (sulphurous acid) SO3 + H20 ===> H2SO4 (sulphuric acid)]

acid_storageNitrogen Dioxide plus Water ends up as Nitric Acid [NO2 + H2O ===> HNO3 + NO]

Homeowner: But acid eats things up!

The Energy Guy:  Yes, it does. These acids start the rust process, I mentioned earlier. The other place you can look for rust is to look at the flue on the roof of some homes. If the coating is attacked by the acids, then rust occurs.

So How do I keep this stuff out of my home and away from my family?

co detectorThe Energy Guy:  First install some Carbon Monoxide Detectors.  If your furnace and water heater are in the basement, you need one down there.  You also need one near bedrooms.

Homeowner: OK!  I’ll get that one that works with my Nest!

The Energy Guy:  That will work for one.   The Nest Protect is like most CO detectors, it will alarm at the higher amounts of CO as required by the Underwriters Laboratory requirements.   These start at 70ppm of CO for an hour. Professional organizations such as ASHRAE and NIOSH list 35ppm as the level for technicians and others to stop work, turn off equipment and evacuate the building. A low level detector is important.

Low Level CO detectors do not meet the UL requirement because they alarm at lower levels, typically 20ppm.    15-20ppm CO levels have been found to impair judgement in people exposed for short periods of time.  The UL testing does not allow a CO detector to pass if it alarms below 30 ppm. Low level CO exposure can result in headaches and general malaise.  If you are exposed to low levels over a period of months or years the effect is unknown at this time.

Homeowner:  OK!  So I’ll get a low level detector also.  What else can I do.

The Energy Guy:  Do some careful air sealing between the garage and the house. You can add exhaust ventilation to your garage as recommended in the International Residential Code. Open the door before you start the car, and then immediately back out. More information about CO and the garage. Air sealing here and a simple closer on the door to the garage will help keep CO and other pollutants from the garage out of the house.

Inside the house, you can buy smart when you replace your water heater or furnace.  Buy sealed combustion units.  These are generally more efficient units, so they will save you some on your bill each month.

95Water Heaters can be sealed combustion, such as the demand models or a power vented unit. Either of these units can be identified with the use of PVC exhaust flue, instead of the metal flue needed by traditional units. They do not need the metal, because the exhaust is a lower temperature. This has a side effect of increased efficiency. The image to the right is the flue of at sealed combustion furnace.

Finally, think about your wood burning fireplace or your gas oven.  These also create the same problems.  Here a low level CO detector would be very valuable. Following the fireplace manufacturers instructions in keeping the glass door shut and having it checked regularly are important.  For a gas range, especially with a gas oven, install an exhaust fan that vents to the outside.

 

Some of this information came from the Maine Indoor Air Quality Council

Some of this information came from the American Lung Association

A Healthy Home — The first of this series

A Healthy Home Part 3 — Well Ventilated

Fresh AirA Healthy Home is well ventilated.  Everyone knows fresh air is important. This should be easy.  Well ventilated in more than just bringing in fresh air. The concepts are certainly easy, the details on the other hand take some thought and planning.  A new home ventilation strategy is fairly straight forward to design and implement. An existing home needs the input from the occupants and good analysis to address the problems. An effective ventilation strategy should address these issues in either new or existing homes.

  • Remove humidity, odors,, or significant problems from specific areas.
  • Remove stale, musty or other objectionable air.
  • Allow the occupants to choose fresh air sources that can be filtered or treated in other ways
  • Allow the occupants to choose to open windows when outside weather is appropriate
  • Allow the occupants to operate a system that can provide the amount of fresh air, to the appropriate places, in adequate amounts when needed
  • Provide fresh air when the outside air creates potential problems, such as Ragweed season or when other allergens are active
  • Provide air movement within the home, without the use of the expensive blower on the furnace or heat pump.
  • Allow minimal use of heating or cooling equipment during the shoulder seasons, when temperature changes are minimal, while keeping the home comfortable.

Billings QuoteHow much fresh air is needed?  Going back to the 1890’s, the number has been pegged at 30 CFM (cubic feet per minute) per person. This number was validated in a number of different studies and with the public health authorities in larger cities, dealing with large apartment buildings and recurring respiratory diseases.  I was pointed to the quote at the left by Allison Bailles. he located the original book on Google Books, page 20.

Beginning in the 1930s, research into changes in building techniques began to show the optimal number was closer to 15 CFM per person.  Some of the changes in construction included the increased use of forced air heating, moving from balloon framing to platform framing, increasing square footage, and the use of insulation in walls and attics. The formula changes from time to time and everyone has an opinion on details. The common point remains, fresh air is needed in every house.

Part of the Ventilation is removing air with a problem. Where is that?  Humidity is found in rooms that use hot water and basements.  Showers, tubs and cooking are the large sources of humidity.  The smells from food preparation and cooking can be very mouthwatering.  When the meal is finished and the refrigerator is full, the lingering smells become odors.  The answer is some spot ventilation in these areas. If your basement has a humidity problem, you can tackle that with a fitted sump pump cover to contain the humidity, and work to eliminate any water seepage.

vent fanSpot ventilation is a window that opens and an exhaust fan. The size of these fans is part of the formula that is specific to each home. The features of the fan are common to all homes.  It must be quiet. Builder grade fans are noisy. Noise in fans is measured in ‘Sones’. The Sone is a linear measurement of noise, compared to the decibels used by OSHA and others which is an exponential measurement.  Linear is better for quiet sounds, and decibels is better for loud noises. Fans should be less than 3 sones, and preferably less than 1 sone.  Reasonably priced fans are available that rate a 0.3 sones. A 1 sone fan is very quiet.

UnknownFans are certified for air flow and noise levels by the Home Ventilation Institute. HVI certification is very common and includes both the Sone rating and CFM rating.  When installing a fan, you must consider the duct losses that will occur in meeting the required air flow.   The rates for bathroom air flow  are 50 CFM, and 100 CFM for a kitchen.  Do not expect to buy a 50 CFM fan for a bathroom and connect it to 6 or 8 feet of duct work, and obtain 50 CFM.  I have measured 30 CFM routinely in these set ups.

Most people understand that various parts of their body are just a part of the whole.  If you start some type of therapy, there may be a side effect. Physical Therapy starts and you end up with some sore muscles, aha!  Side Effect!  Start a therapy for cancer and your hair may fall out, aha! Side Effect!  Your home works the same way.  Each part is just part of the whole. Change something, aha! What is the side effect?

House-System-imgAll of the items in the list above are part of the whole. For an existing home, some specifics of that house may indicate concentration on one or another of those areas.  A home built in the 1920’s will benefit from a different approach then a house built in the 1980’s.

A new home should have the ventilation system that meets the general points above.  The natural ventilation provided when windows and doors are opened, or the mechanical ventilation system that allows filtered and perhaps treated fresh air brought in from specific places and in specific amounts, allow the occupants to make the system work as they need.

 

This post is part of a Series on A Healthy Home