News

Moisture, Mold and Mildew Control in the Home

Key Points

  • Mold and mildew can cause discoloration, odor problems and the degradation of building materials.
  • Moisture control is the most important strategy for reducing the growth of mold and mildew.
  • Thermal bridges, windows and wall cavities are common areas for potential moisture problems.

Mold and mildew are fungi that grow on the surfaces of objects, within pores and in deteriorating materials. They can cause discoloration, odor problems and the degradation of building materials. They can also lead to health problems, including allergic reactions, in susceptible individuals. For mold growth to occur on surfaces, the following conditions must be present:

  • Temperatures ranging between 40°F and 100°F
  • Mold spores
  • Nutrient base (most surfaces contain nutrients)
  • Moisture

Generally, spores are present in the air, and in most commonly used construction materials. Moreover, furnishings and grime on surfaces provide nutrients to support mold growth. Cleaning and disinfecting with non-polluting cleaners and antimicrobial agents provide protection.

Reducing Moisture

Moisture control is an important strategy for reducing mold growth. Mold growth does not require the presence of standing water; it can occur in areas with high relative humidity (RH), or when building surfaces absorb and retain moisture, allowing mold to accumulate.
Maintaining proper humidity levels is possible with energy recovery ventilators (ERV) because they precondition outside air coming into a building, precooling and dehumidifying in summer and humidifying and preheating in winter. Interest in ERV systems has increased in recent years due to lower installation costs, the Air Conditioning and Refrigeration Institute (ARI) Certification program and new building ventilation regulations.
Mold and mildew growth can be reduced where relative humidity near surfaces is maintained below the dew point. This can be accomplished by reducing the moisture content (vapor pressure) of the air, increasing air movement at the surface or increasing the air temperature.
Simply increasing surface temperatures is the best method for reducing surface temperature-dominated mold and mildew. By raising the thermostat setting or modifying air circulation, the supply air is more effective at heating the room surface.

Vapor pressure-dominated mold and mildew can be reduced by direct venting of moisture-generating appliances outside, dilution of moisture-laden indoor air with less humid outdoor air or by dehumidification.

Identifying and Correcting Mold and Mildew Problems

Exterior corners tend to be closer to the outdoor temperature because of poor air circulation, wind-washing, low insulation levels and greater surface area heat loss. As a result, exterior corners are common locations for mold and mildew growth in winter, and in poorly insulated buildings in summer. Buildings with forced-air heating systems and ceiling fans tend to have fewer mold and mildew problems than buildings with less air movement. Removing obstructions to airflow will reduce mold and mildew growth.
Mold and mildew issues can be as extensive in summer as in winter. The same principles apply; either surfaces are too cold, moisture levels are too high or both. A common example of mold growth in summer occurs where cool conditioned air blows against the interior surface of an outside wall, creating a cold spot.
A mold problem can also occur within the wall cavity as outdoor air comes in contact with the cavity side of the cooled interior surface. It is a particular problem in rooms decorated with low-maintenance interior finishes, such as vinyl wallpapers, which can trap moisture between the interior finish and the gypsum board. Mold growth can be rampant when these interior finishes are coupled with cold spots and exterior moisture. Possible solutions for this problem include:

  1. Preventing hot, humid exterior air from contacting the cold interior finish
  2. Eliminating cold spots by relocating ducts and diffusers
  3. Ensuring that vapor barriers, facing sealants and insulation are properly installed and maintained
  4. Increasing the room temperature to avoid over cooling

Thermal bridges are elements of the building structure that conduct heat, causing localized cooling of surfaces. Dust particles sometimes mark the locations of thermal bridges, because dust tends to adhere to cold spots. The use of insulated sheathings significantly reduces the impact of thermal bridges in building envelopes.
Windows have colder surfaces in winter, which can lead to condensation. Condensation is often controlled by using storm windows or insulated glass to raise interior surface temperatures. The advent of higher performance glazing systems has led to a greater incidence of moisture problems because buildings can operate at higher interior moisture levels without visible surface condensation on windows.
Concealed condensation often results from using thermal insulation which, while increasing surface temperatures, also decreases heat loss from the conditioned space into the wall cavity. Wall cavity temperatures are reduced, increasing the likelihood of condensation in this concealed area. Concealed condensation can be controlled in colder climates by installing exterior insulation. In warmer climates, install insulating sheathing to the interior of the wall framing, and between the wall framing and drywall.
Heating, ventilating and air conditioning (HVAC) systems
HVAC systems play an important role in controlling moisture and mold. Make sure your system is sized correctly for your facility and maintain a program of regularly scheduled maintenance and inspections. AAC Services is here for you and we are happy to help.

 

Article supplied by Consumers Energy

Why Is My Furnace Leaking Water?

As the temperature begins to dip, one of the last things you want is to have issues with your furnace. If you begin to see water forming around the unit, you may start to worry and wonder what’s happening. Usually, this signifies that something...

Reasons Your Furnace Isn’t Blowing Out Hot Air

It’s the middle of winter and you’re trying to warm up. You check to make sure all the windows are closed, there are no drafts or cracks allowing cold air to escape in. It’s still cold in your home. What’s the issue then? The...

Why Isn’t My Hot Water Hot?

One of the worst feelings is stepping into a shower–only to find out there’s cold water pouring out. Without reliable hot water, you can’t shower, wash your dishes, or carry out any number of other activities that involve water. Here are a couple reasons as...

Common Furnace Malfunctions

The only time you need your furnace is when the weather cold (or frigid!). At those times, the furnace may stop working at 1:00 am, you wake up with goosebumps, become desperate for warmth, and you don't know how to troubleshoot the furnace problem. Common furnace...

Why You Should Inspect Your AC Unit At The End Of The Season

Central air conditioners are connected to many homes for cool air during summer or warm air during the winter. Therefore, the cooling and heating systems require regular maintenance to check for any malfunctions before you begin the next season of air conditioning within your...

Common Boiler Malfunctions

Many people do not give much thought to the central heating system.  People expect it to work when they need it and for it to continue pumping out a continous supply of hot water. However, if there is a fault, or the boiler is malfunctioning, it...

Why Does My AC Keep Running?

When an air conditioning unit is constantly running, it is not only blowing money, but it's a sign that something isn't right with the unit. An air conditioner should kick on and off automatically unless there is an issue. An air conditioner that runs...

What Are The Most Common AC Malfunctions?

Your home air conditioner is one of the most important appliances in your home. While air conditioners that are well-maintained can last for a long time, it always seems as if they malfunction at the worst possible times. Fortunately, many of the reasons for...

Why Is My AC Unit Not Cooling Down My Home?

If you are experiencing higher temperatures in your home than set on your thermostat, it can make your stay frustrating and uncomfortable. The problem might be simple or it might mean you need a new AC unit. Why is your AC not cooling the...

How To Safely Clean Your AC Unit

One of the easiest ways to extend the life of your AC unit as well as to ease the task of maintenance is to make sure the AC unit is clean. A clean air conditioning unit will also allow your home to be cooled...

Common Air Conditioning Malfunctions

As the temperature rises on the outside, you want the temperature to drop on the inside. One of the worse things that can happen on a sweltering summer day is a malfunctioning AC unit, causing you and your family discomfort. Below are just a few issues that...

HVAC License-Dangers and Risks

Are you putting your family in Danger?
Do you know if your contractor has an HVAC License?  You would think the question of possessing the proper HVAC license would be an easy one to answer.  Ha!  Not here in Michigan, just visit-  LARA –...

Breath Better, Live Healthier with quality air filters

Furnace or Air Condition Filters for Health and Savings
When you have a central furnace and air conditioning system, air quality often becomes an issue, affecting how you breathe, your health and the basic quality of life indoors.  These types of systems use...

Is Your Air-Conditioning System Ready for Warm Weather?

Is Your Air-Conditioning System Ready for Warm Weather?
This is the focus I’ll be tackling here on this post, enjoy.
While cooling is essential for facility comfort and productivity, it accounts for nearly 15 percent of the electricity used in residential homes...

Ductless Split-System Heat Pumps (Mini-Splits)

 This article is reproduced from the U.S. Department of Energy Website.??Ductless split-system heat pumps (mini splits) make good retrofit add-ons to houses with “non-ducted” heating systems, such as hydronic (hot water heat), radiant panels, and space heaters (wood, kerosene, propane). They can also be...

Ten Ways to Improve Heating System Performance

Key Points

Optimizing heating system performance can save on energy costs and improve building comfort.
Regular maintenance and efficiency upgrades can keep your system operating at peak efficiency.
If your system is 15 years old or older, consider installing...

Refrigerant Battle of the 21st century

R22 vs R410, Why the Big Scare.
Today 5/9/2017
I would like to start by saying this is an update from 2012. Since this article was posted a few thing have changed. The biggest change has been the cost of the R-22, it...

Heating Tax Credits for 2011

$500 -- 2011 HVAC Energy Tax Credit
Although not as aggressive as the past two years of energy tax credits, the new round of tax credits are here for 2011.
When an aging or unreliable comfort system is due for repair, it...

Thermostats

Home Furnace Thermostat
Adam’s video pick to help with your project-http://www.youtube.com/watch?v=8cXvcs9VXXI&feature=related

The furnace thermostat is the nerve center of your home heating system. It’s the main control point that determines when and how much heat will be produced by the...