Indoor Air Quality
By: Amanda Campbell
Updated: August 13, 2010
We've come a long way in the last few years developing good techniques for building new houses that are well-insulated and tightly sealed against leaks. That saves us money on our energy bills but it can actually make the air inside our homes less healthy. By sealing the house we make it hard to bring fresh air in, unless we design a system that introduces fresh air inside. Without fresh air, moisture builds up that can make mold & mildew grow. The EPA estimates that indoor pollutants can be 10 times greater than air in the smoggiest city. They call it "sick building syndrome." The quality of your indoor air is a very important issue in new home construction. We'll show you how you can keep the inside air healthy in your new house.
* Bryant Heating & Cooling provided the Two-Stage Furnaces, Air Conditioners & Humidifiers we featured in this segment
* GE Industrial Systems provided the ECM Variable Speed Motors we featured in this segment.
* Stirling Technology, Inc. provided the Energy Recovery Ventilators we featured in this segment
* Pure Air Systems, Inc. provided the HEPA Filter System we featured in this segment.
* Paul Goldman from GE joined Michael on this segment to help explain the system we installed to guarantee Indoor Air Quality
HVAC Defined
"Heating, Ventilation & Air Conditioning". We often ignore the "V" in HVAC
A "Tight House" Defined
Modern insulation and house-wrapping techniques create a tightly sealed envelope that blocks leaks, drafts and other unintentional paths for fresh air to enter a house.
A "Sick House" Defined
Insulation and house-wrapping create a "stale air" environment inside. The air gets stale because the same air keeps getting conditioned - you notice it inside an airplane cabin sometimes. Without proper ventilation, moisture can build inside a house. That moisture can not only rot the wood in the frame of your house, but it can promote the growth of mold, mildew & other biological pollutants.
Indoor Air Quality is defined as a Three-Stage Concern Introduction of Fresh Air, Air Filtration & Humidity Control
Stage #1
Introduction of Fresh Air into the house with an Energy Recovery Ventilator or ERV- If you want fresh air, why not just open a window? The goal is both to provide fresh air & conserve energy. The ERV is a device designed to bring fresh air from outside the house and exchange it with the "stale air" inside your house. That stale air holds a lot of energy - energy you've already paid for (because you've cooled it in the summer and heated it in the winter). ERV's are available from a number of manufacturers; we featured one from Stirling Industries powered by a GE motor. An ERV is a combination ventilator and enthalpies heat exchanger (that means it extracts both heat and humidity). That's important, because some exchangers only exchange heat, and they ignore the moisture content in the air. For optimum efficiency & comfort an exchanger must do both.
Here's how the ERV ventilates
The ERV has two sets of inlets & outlets- one set on the outside of the house & one set that runs into the boxes (called plenums) that feed into the HVAC system . On the outside of the house, the inlet brings fresh air in and the outlet removes stale air from inside the house. On the HVAC unit, the inlet accepts fresh air that's just passed through the ERV and the outlet feeds stale interior air to the ERV. That establishes a constant circular flow of "fresh air in and stale air out".
Here's how The ERV Saves or Recovers Energy
This circulating flow of air converges or meets inside the ERV (it's basically a big black box). Energy (in the forms of heat and humidity) transfers between the inside "stale" air (hotter or cooler than the outside air, depending on the season) and fresh air coming in from the outside. This energy transfer takes place before incoming air enters the living space of the house through the inlet ducts on the plenum.
HVACThe ERV is designed to provide a complete change of air every three hours. The ERV will conserve up to 90% of the energy that goes through it. So in the winter, if it's 0 degrees outside and 70° inside, the incoming air will be heated to 64°. In the summer, if it's 100° outside and 70° inside, the incoming air will be cooled to 73°. So the HVAC system doesn't have as much work to do (getting the fresh outside air to the same temperature as the inside air) as it would if you just opened a window to get fresh air in.
Consumer Tip - The ERV has an ECM variable speed motor, built by GE. "ECM" stands for "Electronically Commutated Motor". This is a "smart" motor. Think of it like the processing chip that runs your home computer. It has the ability to blow air at varying speeds to provide just the right amount of airflow for any heating or cooling requirement.
When the difference between outside and inside temperatures is extreme, this "smart" motor may slow down the flow of air through the ERV to maximize the energy transfer. That happens because energy "travels" from hot to cold. The longer that air sources at different temperatures are exposed to each other, the better the temperatures will equalize.
HVACThe ECM motor is even smart enough to maintain a proper airflow by speeding up when the air filters load up with dirt like this. Plus the ECM Motor uses very little electricity (open up to reveal light bulb panel). A typical blower will use about 400 to 600 watts - that's enough power to light up ten light bulbs. An ECM motor will use only about 75 watts. It's also incredibly quiet, because it runs on DC power.
Stage #2
Air Filtration with a HEPA filter - This is a machine for reducing airborne contaminants that can trigger conditions such as asthma and allergies. It's the most efficient filter you can buy. Hospitals use them to keep the air in surgical suites clean. This one is made by Pure Air Systems and it attaches to the return air duct The HEPA Filter draws the return air into the filter cabinet where it goes through 3 distinct filters.
The pre-filter is made of 2 polyester rings which trap large dust particles - these particles are the kind you can see floating around the house, but they're large enough so they can't really get into your lungs & do damage. The 2nd is a carbon filter that removes odors and gases. The last layer is the HEPA filter which removes nearly all of the tiny particles that can lodge in your lungs & threaten your health - things like pollen, bacteria, mold spores, and tobacco smoke. How does it work? This system has its own ECM blower motor (just like the ERV) to move the air through the filters and it can run whether the AC or furnace is on or off. If you run it all the time, the air will be cleaned twice every hour, or 48 times a day. And because it's equipped with a high-efficiency ECM motors, it only costs pennies a day to operate. You have to change the pre-filter once every 3 months; the carbon filter once a year; and the HEPA filter once every 3 years.
Stage #3
Controlling humidity is vital to both comfort and health. When it comes to maintaining a healthy environment, there is an ideal level of humidity, generally between 35 and 40%. Go above that range and you can create an environment conducive to growing mold, mildew, bacteria and viruses. Go below it and you're more susceptible to catching a cold or the flu because dry air irritates your sinuses. In the winter, you can also get those jolts of static electricity.
The system we installed in our Project House delivers ideal humidity year round. In winter, the Bryant humidifier will automatically add moisture vapor while the furnace is running. In the summer it removes moisture while the AC is running That's important because in the winter, the relative humidity in a heated house can drop below 15%, which is less than most deserts. This humidifier adds up to 25 gallons of water a day to the air in winter. All this moisture helps prevent skin and nasal passages from getting too dry. It also prevents cracking in wood floors and furniture. Plus, with enough moisture, you feel warmer so you can keep your thermostat set a little cooler and save on energy.
Here's how the Humidifier operates
HumidifierFirst, there's an incoming water supply that runs to the humidifier. Then the humidistat in each room or zone will work just like a thermostat so that the homeowner can control the amount of moisture output. It's completely automatic; just set it and forget it. That takes care of winter. In summer, that same humidistat will help because it will tell the AC when it's a really humid day so it can remove more moisture from the air.
Since we're using a two-stage AC with an ECM Motor, just like in the ERV & the HEPA Filter, this system is smart enough to adjust the airflow in the AC. That means we can remove about six buckets of water a day from this house in the summer where a normal AC would only remove about 1 bucket a day. That's going to make the house more comfortable. It's also going to keep the humidity in the house in that ideal range of 35-40% which keeps bacteria, mold and dust mites to a minimum. Lower-cost alternatives to this state-of-the-art system - Manufacturers offer "pleated" air filters that cost $300-400 installed.
You can find even more economical air filters at any home supply store. Neither can match the HEPA filter's capability, especially when it comes to the tiniest particles that can irritate the lungs. The HEPA filter systems in the Project House cost about $3000. Even if this is beyond your reach, your goal is air filtration of some kind to clean the air of the things that will make you ill.
Our segment showed you a state-of-the-art system meant to control a million-dollar home. If this is beyond your price range, think about at least installing some kind of filter system into your HVAC. Make sure your builder includes a fresh air circulation system in your HVAC so all those indoor pollutants like household chemicals, cigarette smoke and even radon have a way to escape.
Use humidifiers in the winter and dehumidifiers in the summer. A recent study in Massachusetts determined that half of all illnesses reported in the US were caused by indoor pollution. Any money you spend on improving indoor air quality is a bargain, because it helps to ensure the good health of you and your loved ones year-round in your new house.
* Bryant Heating & Cooling provided the Two-Stage Furnaces, Air Conditioners & Humidifiers we featured in this segment
* GE Industrial Systems provided the ECM Variable Speed Motors we featured in this segment.
* Stirling Technology, Inc. provided the Energy Recovery Ventilators we featured in this segment
* Pure Air Systems, Inc. provided the HEPA Filter System we featured in this segment.
* Paul Goldman from GE joined Michael on this segment to help explain the system we installed to guarantee Indoor Air Quality
HVAC Defined
"Heating, Ventilation & Air Conditioning". We often ignore the "V" in HVAC
A "Tight House" Defined
Modern insulation and house-wrapping techniques create a tightly sealed envelope that blocks leaks, drafts and other unintentional paths for fresh air to enter a house.
A "Sick House" Defined
Insulation and house-wrapping create a "stale air" environment inside. The air gets stale because the same air keeps getting conditioned - you notice it inside an airplane cabin sometimes. Without proper ventilation, moisture can build inside a house. That moisture can not only rot the wood in the frame of your house, but it can promote the growth of mold, mildew & other biological pollutants.
Indoor Air Quality is defined as a Three-Stage Concern Introduction of Fresh Air, Air Filtration & Humidity Control
Stage #1
Introduction of Fresh Air into the house with an Energy Recovery Ventilator or ERV- If you want fresh air, why not just open a window? The goal is both to provide fresh air & conserve energy. The ERV is a device designed to bring fresh air from outside the house and exchange it with the "stale air" inside your house. That stale air holds a lot of energy - energy you've already paid for (because you've cooled it in the summer and heated it in the winter). ERV's are available from a number of manufacturers; we featured one from Stirling Industries powered by a GE motor. An ERV is a combination ventilator and enthalpies heat exchanger (that means it extracts both heat and humidity). That's important, because some exchangers only exchange heat, and they ignore the moisture content in the air. For optimum efficiency & comfort an exchanger must do both.
Here's how the ERV ventilates
The ERV has two sets of inlets & outlets- one set on the outside of the house & one set that runs into the boxes (called plenums) that feed into the HVAC system . On the outside of the house, the inlet brings fresh air in and the outlet removes stale air from inside the house. On the HVAC unit, the inlet accepts fresh air that's just passed through the ERV and the outlet feeds stale interior air to the ERV. That establishes a constant circular flow of "fresh air in and stale air out".
Here's how The ERV Saves or Recovers Energy
This circulating flow of air converges or meets inside the ERV (it's basically a big black box). Energy (in the forms of heat and humidity) transfers between the inside "stale" air (hotter or cooler than the outside air, depending on the season) and fresh air coming in from the outside. This energy transfer takes place before incoming air enters the living space of the house through the inlet ducts on the plenum.
HVACThe ERV is designed to provide a complete change of air every three hours. The ERV will conserve up to 90% of the energy that goes through it. So in the winter, if it's 0 degrees outside and 70° inside, the incoming air will be heated to 64°. In the summer, if it's 100° outside and 70° inside, the incoming air will be cooled to 73°. So the HVAC system doesn't have as much work to do (getting the fresh outside air to the same temperature as the inside air) as it would if you just opened a window to get fresh air in.
Consumer Tip - The ERV has an ECM variable speed motor, built by GE. "ECM" stands for "Electronically Commutated Motor". This is a "smart" motor. Think of it like the processing chip that runs your home computer. It has the ability to blow air at varying speeds to provide just the right amount of airflow for any heating or cooling requirement.
When the difference between outside and inside temperatures is extreme, this "smart" motor may slow down the flow of air through the ERV to maximize the energy transfer. That happens because energy "travels" from hot to cold. The longer that air sources at different temperatures are exposed to each other, the better the temperatures will equalize.
HVACThe ECM motor is even smart enough to maintain a proper airflow by speeding up when the air filters load up with dirt like this. Plus the ECM Motor uses very little electricity (open up to reveal light bulb panel). A typical blower will use about 400 to 600 watts - that's enough power to light up ten light bulbs. An ECM motor will use only about 75 watts. It's also incredibly quiet, because it runs on DC power.
Stage #2
Air Filtration with a HEPA filter - This is a machine for reducing airborne contaminants that can trigger conditions such as asthma and allergies. It's the most efficient filter you can buy. Hospitals use them to keep the air in surgical suites clean. This one is made by Pure Air Systems and it attaches to the return air duct The HEPA Filter draws the return air into the filter cabinet where it goes through 3 distinct filters.
The pre-filter is made of 2 polyester rings which trap large dust particles - these particles are the kind you can see floating around the house, but they're large enough so they can't really get into your lungs & do damage. The 2nd is a carbon filter that removes odors and gases. The last layer is the HEPA filter which removes nearly all of the tiny particles that can lodge in your lungs & threaten your health - things like pollen, bacteria, mold spores, and tobacco smoke. How does it work? This system has its own ECM blower motor (just like the ERV) to move the air through the filters and it can run whether the AC or furnace is on or off. If you run it all the time, the air will be cleaned twice every hour, or 48 times a day. And because it's equipped with a high-efficiency ECM motors, it only costs pennies a day to operate. You have to change the pre-filter once every 3 months; the carbon filter once a year; and the HEPA filter once every 3 years.
Stage #3
Controlling humidity is vital to both comfort and health. When it comes to maintaining a healthy environment, there is an ideal level of humidity, generally between 35 and 40%. Go above that range and you can create an environment conducive to growing mold, mildew, bacteria and viruses. Go below it and you're more susceptible to catching a cold or the flu because dry air irritates your sinuses. In the winter, you can also get those jolts of static electricity.
The system we installed in our Project House delivers ideal humidity year round. In winter, the Bryant humidifier will automatically add moisture vapor while the furnace is running. In the summer it removes moisture while the AC is running That's important because in the winter, the relative humidity in a heated house can drop below 15%, which is less than most deserts. This humidifier adds up to 25 gallons of water a day to the air in winter. All this moisture helps prevent skin and nasal passages from getting too dry. It also prevents cracking in wood floors and furniture. Plus, with enough moisture, you feel warmer so you can keep your thermostat set a little cooler and save on energy.
Here's how the Humidifier operates
HumidifierFirst, there's an incoming water supply that runs to the humidifier. Then the humidistat in each room or zone will work just like a thermostat so that the homeowner can control the amount of moisture output. It's completely automatic; just set it and forget it. That takes care of winter. In summer, that same humidistat will help because it will tell the AC when it's a really humid day so it can remove more moisture from the air.
Since we're using a two-stage AC with an ECM Motor, just like in the ERV & the HEPA Filter, this system is smart enough to adjust the airflow in the AC. That means we can remove about six buckets of water a day from this house in the summer where a normal AC would only remove about 1 bucket a day. That's going to make the house more comfortable. It's also going to keep the humidity in the house in that ideal range of 35-40% which keeps bacteria, mold and dust mites to a minimum. Lower-cost alternatives to this state-of-the-art system - Manufacturers offer "pleated" air filters that cost $300-400 installed.
You can find even more economical air filters at any home supply store. Neither can match the HEPA filter's capability, especially when it comes to the tiniest particles that can irritate the lungs. The HEPA filter systems in the Project House cost about $3000. Even if this is beyond your reach, your goal is air filtration of some kind to clean the air of the things that will make you ill.
Our segment showed you a state-of-the-art system meant to control a million-dollar home. If this is beyond your price range, think about at least installing some kind of filter system into your HVAC. Make sure your builder includes a fresh air circulation system in your HVAC so all those indoor pollutants like household chemicals, cigarette smoke and even radon have a way to escape.
Use humidifiers in the winter and dehumidifiers in the summer. A recent study in Massachusetts determined that half of all illnesses reported in the US were caused by indoor pollution. Any money you spend on improving indoor air quality is a bargain, because it helps to ensure the good health of you and your loved ones year-round in your new house.
