When temperatures start to rise in late spring and early summer, a common reaction is to turn on the air conditioner or heat pump for indoor cooling. A better and more economical option could be to rely on ventilation to reduce your home's indoor temperature. Here are some techniques for using ventilation to boost cooling and save money on your energy bill.
Ventilation for Cooling
Ventilation is commonly thought of as a way to remove particulates, contaminants and odors from your indoor environment. While ventilation is certainly effective at freshening your indoor air and improving indoor air quality, it can also help remove the heat and moisture that make your living spaces uncomfortable. Proper ventilation reduces indoor heat levels and reduces the workload for your cooling system. Ventilation also removes the moisture and humidity that affects you physically by making you feel warmer. When outdoor temperatures are mild, ventilation can cool your home sufficiently to forego turning on your air conditioner or heat pump so you can save energy and money.
Natural ventilation is the quickest, easiest and least expensive method of providing ventilation and cooling for your home. By using natural ventilation, you take advantage of early morning cooling, shade, wind and other cooling sources when they are available. Natural ventilation also involves reducing or avoiding the accumulation of heat in your home.
- Open windows at night: When humidity levels are low, open windows at night to let in fresh, cool air. Putting a box fan in the window will increase the amount of cool air being brought inside.
- Use breezes and wind for cooling: When breezes are blowing outside, open windows to use these cooling drafts inside. Wind moving around your home creates areas of negative and positive pressure that can improve heat removal and cooling. Positive pressure pulls cool air inside while negative pressure moves warm air outside. Try several combinations of open/closed windows to see which provides the best airflow throughout your home.
- Close windows and doors when daytime temperatures are highest: Closing doors and windows against daytime temperatures will help maintain indoor cooling that occurred overnight.
- Close windows when humidity is high: Open windows allow humidity into your home. As moisture levels increase, your air conditioner will have to work harder to keep it under control. High levels of humidity also will make you feel hotter and more uncomfortable. So keep your windows closed when your A/C is running and the outdoor humidity is high.
- Apply techniques to prevent heat gain: Heat gain is the accumulation of heat inside your home caused by sunshine or other heat sources. Apply window treatments to block sunlight. Close shades and drapes to reduce this solar gain. Install awnings over your windows to keep sunlight from reaching them. Replace windows, if feasible, with features such as low-e glass, insulated glass units, and thorough seals.
Circulating Fans and Exhaust Fans for Ventilation
Circulating fans are among the simplest, most common and most easily accessible types of ventilation systems. They are used to increase air circulation inside your home and create air drafts that can cool you directly. Exhaust fans enhance circulation that helps pull stale air and contaminants out of your residential interiors while moving in fresh, clean air from outside. Exhaust fans are sometimes mounted directly into the wall, while others are equipped with ducts that direct stale, contaminated air out of your home. You can find exhaust fans used for cooling in areas such as:
- Bathrooms: Odors, excess moisture and heat from bathing are removed.
- Kitchens: Cooking odors, heat, steam, moisture and particulates are removed.
- Laundry rooms: Moisture and heat from washers and dryers are removed.
Your HVAC professional can help you decide if a permanently mounted exhaust fan is best for your situation, or if a portable fan would be the better option.
Some of the more common types of fans include:
- Standard window or box fans: These portable fans are inexpensive and easily found in retail stores. A box fan in one or more windows of your home can significantly reduce the temperature inside your home by bringing in cooler outdoor air. The influx of fresh air will improve indoor air quality. The airflow provided by the fan also will cool you directly as the breeze from the fan hits your body.
- Ceiling fans: Ceiling fans help move around cool air that has accumulated in the lower portions of rooms. In addition, the drafts from ceiling fans provide direct cooling, via the wind-chill effect.
- Wall-mounted exhaust fans: These fans are installed in exterior walls and provide a direct flow of air from the inside of your home to the outdoors. They normally do not require ducts. They often are used in kitchens, bathrooms and garages. Wall-mounted exhaust fans are very effective at removing heat, moisture and odors, but they also can pull excessive amounts of conditioned air out of the inside of your home. If not properly installed and sealed, they can allow air and energy leaks that could increase your monthly energy expenses.
- Ceiling-mounted exhaust fans: These fans work much like wall-mounted units, except they are placed in ceilings and are connected to capped exhaust ducts that extend through the roof.
- Inline exhaust fans: Inline exhaust fans are placed between ducts. They are effective in situations where there's not enough space to put in a ceiling-mounted fan. They can provide as much ventilation as other types of fans and can be configured to exhaust heat, moisture and indoor air to single locations or multiple areas.
- Exterior remote-mounted exhaust fans: These exhaust fans are placed on the outside of your home. They pull out heat, moisture, stale air and contaminants.
- Kitchen range exhaust fans: Kitchen range fans are usually installed within the hood of your cooking equipment where they pull out heat, steam, odors and particulates produced by cooking.
Whole-house ventilation systems work to produce additional air circulation and ventilation for your entire house, rather than just one room or area. Whole-house systems include:
- Exhaust ventilation: Exhaust ventilation systems move air out of your home by depressurizing the indoors, using a fan installed at a central point. When indoor pressure is lower than outdoor pressure, air is removed through exhaust vents and openings in the building's frame.
- Supply ventilation: Supply ventilation pressurizes the inside of the home to pull air inside through a central supply fan. Stale air exits from vents, ventilation fans, and structural gaps and openings.
- Balanced ventilation: Balanced ventilation systems use two sets of fans to create a balanced inflow and outflow of air. Though these systems can be more costly than other types, they are very effective at producing effective whole-house ventilation that cools the interior, removes moisture, and gets rid of stale air.
When making plans for installation of ventilation systems, pay particular attention to the attic area. Attics, especially unfinished or uninsulated ones, can get extremely hot in the summer as sunshine beats down on the roof. This accumulated heat will radiate downward into your home, increasing indoor temperatures of every room and area beneath the attic. In addition, the excessive heat in the attic could cause damage to items stored there, the roof, the attic floor, and the framework surrounding the attic. You can reduce the effects of attic heat by installing:
- Attic fans: These types of fans will produce a consistent airflow in the attic that will get rid of both heat and moisture. An effective attic fan should be able to replace the entire volume of air in the attic at least 10 times per hour.
- Vents: Ridge or rafter vents boost ventilation while also decreasing heat and moisture. They should be placed where the ceiling of the attic meets the attic floor. In general, each 300 square feet of attic space should have 1 square foot of ventilation.
Heat and Energy Recovery Ventilation
If you're concerned about losing cool air from your home during ventilation processes, a heat recovery ventilator (HRV) or energy recovery ventilator (ERV) may be your best choice. HRVs and ERVs serve as whole-house ventilators, but they are designed to transfer heat energy between the inflowing and outflowing air. When cooling, the latter occurs. This way, you have less heat gain during ventilation and do not have to rely on your cooling system to work harder to make up for the loss.
HRVs and ERVs produce both ingoing and outgoing streams of air. Both streams are directed through the system, where they enter a heat exchanger and pass close by each other without actually mingling. When the air streams are close, the heat exchanger transfers heat energy to the outflowing air, reducing the temperature of the air coming into the house. ERVs differ from HRVs in that they also transfer moisture, helping control the humidity in your home.
Comfort24-7.com offers reliable, professional HVAC services to residential clients in northwest Indiana, southwest Michigan and the Chicago area. Contact us today for more information on home ventilation and how it can be used to improve indoor cooling while reducing costs throughout the summer season.
Written by Randy Gailit