Today’s green building techniques are resulting in tight building envelopes. This allows homes to be more efficient than ever before and helps keep energy bills low. Today’s building science also requires home ventilation to be looked at in new ways. Tight building envelopes require proper air exchange to manage indoor air quality.
With today’s homes being tighter than ever, there is less opportunity for air to naturally escape. When you combine this with an increase the number of additives in today’s building products, indoor air quality can become quite poor. If you live in a newer, energy-efficient home, you need a controlled ventilation system to maintain optimal air quality.
There are many types of ventilation systems available for a home. Two common systems are not energy efficient options and are not recommended. These are:
- Exhaust Only – A small exhaust fan is programmed to pull out stale air and moisture. The home relies on natural air leaks to bring air into the home (not an energy-efficient option).
- Supply Only – A fan brings fresh air into the home. Air is not mechanically vented out. The home relies on natural air leaks to vent air from the home (not an energy-efficient option).
A balanced ventilation system includes both exhaust and supply to control ventilation at both ends. This system includes separate fans to manage air supply and air exhaust and create an energy-efficient ventilation balance. This system can go one step further by adding heat recovery which conditions the incoming air prior to entering the home. This is a great system for cold climates, preventing cold air from being drawn into the home during winter.
Does your home have a ventilation system? Do you have questions about your home’s air sealing and ventilation? Contact us with any questions.
Since insulation’s beginning, it was installed with the purpose of creating a thermal barrier around a building — and keeping those inside safe, comfortable, and protected from the elements. Little did we know building science would come on the scene and change our industry in a big way. And it’s here to stay.
There is a lot to know about building science — we’ve taken the time to break it down for you.
Much of building science focuses on air flow. Improper air flow can have severe effects on the health and safety of the people in the building. It can also cause mold growth, spread pollutants and more. Controlling air flow increases the efficiency of a building, reduces stress on mechanicals and controls indoor air quality.
There are a few key conditions that affect air flow (courtesy ENERGYSTAR.gov):
- Controlled versus uncontrolled airflow
- Controlled air flow is generated by a mechanical device and is designed to help ventilate a building and/or distribute conditioned air throughout a building. Ventilation systems, fans and heating and cooling systems are typical sources of controlled air flow.
- Uncontrolled air flow is unintended air flow into, out of, or within a building. This can be caused either by wind, warm air rising in the building, uncontrolled fans and leaks in an air handling system.
- Air pressure from wind, heat, fans and duct systems
- Pressure differences across holes, boundaries, and barriers within a building are caused by one of four forces:
- Wind blowing against a building can cause large pressure differences between one side of the building and the other.
- Heat and the buoyancy of hot air affects air pressure. Heat naturally attempts to rise to the top of a building (called stack pressure or stack effect. The amount of pressure depends on the temperature difference between the inside and outside of the building, as well as the height of the building.
- Fans (particularly exhaust fans and HVAC air handlers) can contribute to pressure changes in several different ways. Leakage in the building envelope or the ducting, or an imbalance in the supply and return ducts can cause these fans to have a drastic effect.
- Duct systems that leak to the outside of the building on both the supply and return sides of the system can cause infiltration rates to increase by as much as 300%.
- Holes and pathways
- Uncontrolled air flow (infiltration) into a building is a result of holes in the building’s shell. By reducing the number of holes in the building, and you reduce the amount of uncontrolled air flow. Buildings have two kinds of holes: designed holes and undesigned holes.
- Undesigned holes in the home are found in the attic, walls, and floors. Any of these holes that connect to the outdoors should be adequately blocked, caulked, gasketed, or otherwise adequately sealed
- Designed holes include any hole or system that is designed to have air passing through it in a specific direction. Examples of such holes include flues and combustion vents, chimneys, make-up fans, exhaust fans, dryer vents, cooktop fans, ventilation systems, central vacuums, windows and doors, and fresh air inlets/outlets.
All of these things are incredibly important conditions to consider when improving the energy efficiency of a home or business. The way air moves through a building matters — and it ultimately determines how comfortable (and healthy) you are where you live as well as how much it will cost you for that comfort over the lifetime of your home.
Have questions on the air flow in your home or building? Give us a call today!