What Will Solar Attic Fans Be Like In The Next 50 Years?

Easily installed and free to operate, solar attic fans are a smart choice for homeowners who want to save money cooling their homes in summer, prevent ice dams in winter, and extend the lives of their roofs.

Operating Principle

A solar attic fan uses photovoltaic panels to convert sunlight into electrical power. The electricity generated is used to turn a fan motor, exhausting air from the attic of a home.

Benefits

In summer, temperatures in an unventilated attic can exceed 160 degrees F. A properly sized solar attic ventilation system will reduce attic temperature to 5-10 degrees F above the outdoor temperature. Ventilating the attic reduces the amount of heat transferred from the attic to the home, decreases the load on the air conditioning system (reducing your electric bill), and extends the life of the roof.
In winter, heat trapped in the attic may melt snow on the roof, which trickles down and creates destructive ice dams in the colder eaves.
The attic becomes warmest when the sun is the strongest. A solar attic fan runs the hardest when the sun is strongest.
Everyday home activities such as cooking and showering create moisture which collects in the attic and promotes mold and mildew growth, reduces the effectiveness of insulation, and attacks the wooden attic structure. Year round fresh air circulation from a solar attic fan removes this moisture and prevents moisture related problems.
Zero operating cost.
Installation can be done by a handy homeowner. No electrician is required.
Quiet operation.
Things to Consider
· The cost savings due to reduced air conditioner load depends on the price of electricity in your area, the amount of attic space in your home, the efficiency of your attic insulation, and the amount of ventilation your solar attic vent is able to provide. A typical installation will usually pay for itself in savings within 1-2 summers of use.

· A solar attic fan should not be used when air from the living areas of the home can freely enter the attic. This would result in conditioned air being removed from the home. Any openings between the attic and the home should be sealed before a solar attic fan is installed.

· Properly sized attic vents are required to allow fresh air to enter the attic and replace the hot air removed by the solar attic fan.

· Solar attic fans should be mounted away from ridge vents and gable vents.

Configurations

Solar attic fans are available three configurations:

1. Self flashing roof solar attic fan: The fan base is flat and designed to slide under shingles and attach directly to the roof.

2. Curb mounted solar attic fan: The fan base is a cap designed to fit over a curb which is attached to the roof.

3. Gable fan: The fan exhausts horizontally through the gable end of the attic.

In addition, solar attic fans are available with fan mounted or remote solar panels.

Installation Overview

1) Cut hole in roof (South side is recommended), taking care not to cut through any roof framing members.

2) Slide unit under shingles

3) Reshingle around fan as necessary.

Commonly Asked Questions

1) What size fan do I need?

ANSWER: A solar attic fan should be sized to provide 10 attic air volume changes per hour.

To figure out what flow rate this works out to, figure out the volume of your attic in cubic feet. Multiply your attic volume x 10 air changes per hour to get the total flow required per hour.

Since fans are sized in terms of their cfm (cubic feet/minute) output, divide your total flow per hour by 60 to get cubic feet per minute.

Required flow rate in cfm = (attic volume x 10) / 60

Now check the fan specifications to find the fan or combination of fans required to meet your ventilation needs.

It is also very important to make sure there is enough air inlet area in your attic to allow fresh air to enter and replace the hot air being exhausted. A minimum of 1 square foot for every 360 cfm of exhaust is required. Typically soffit vents are used as inlets.

2) How long will a solar attic fan last?

ANSWER: Solar attic fans are designed to provide many years of trouble free operation. The length of manufacturers' warranties are a good indicator of the high standards these fans were designed to:

Attic Breeze Fans - Lifetime parts warranty

Solar Star Fans - 5 Year parts on solar panel and motor, 10 years on all other parts.

Natural Light Fans - 25 Year parts warranty

SunRise Solar Fans - 5 year parts warranty on motor, 10 years on all other

3) How is a solar attic fan controlled?

ANSWER: A thermal switch is often used to control a solar attic fan. This switch only allows the fan to run when the attic is warmer than 80-90 degrees F. Running the fan only when the attic is hot extends the life of the fan motor and results in less heat loss to the attic in winter, but does not allow the fan to reduce moisture build-up in the attic at all times and does not allow the fan to prevent ice dams during the winter.

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Ten Useful Tips From Experts In Fan

With the ability to increase the comfort, value, and beauty of your home, indoor and outdoor ceiling fans are a truly worthwhile investment. Today, there are countless ceiling fan options on the market, from budget-friendly, "builder grade" fans to more elaborate, with ornate styling like that of a fancy chandelier.

How do you go about choosing the right one, with so many options available? Just follow these easy guidelines!

Choose a high-quality motor. Contrary to popular belief, it is the quality of the motor (not the design or appearance) that you are really paying for in a ceiling fan. The difference between high-quality and the lower-quality fans is all in the motor. Lower quality fan motors usually have a thin metal covering, which can cause rattling and other unpleasant noises when running. High quality fans, on the other hand, have a heavy gauge steel motor case. These motors are both quieter and more aesthetically pleasing.
Choose An Outdoor-Specific Fan for Outside. Outdoor-specific fans are made with more durable materials to withstand the elements, whereas indoor fans are not. Indoor ceiling fans installed outdoors will eventually swell from humidity, resulting in unsightly drooping and lowered performance. While browsing outdoor fans, always consider the climate where you live and the area of the home where you'll install the fan. UL "Damp" rated fans can be used under a covered porch or patio, but you'll need a "Wet" rated fan for use in more open areas like gazebos or pergolas.Consider the Ceiling Fan's Efficiency and Air Movement. Although almost all fans can help you save on your air conditioning bill, models that are Energy Star rated are particularly efficient.
When measuring efficiency, the key factor is airflow: how much air can this ceiling fan really move? This is determined by the quality of the motor, the angle (or pitch) of the blade, and material of the blade. The best angle for residential ceiling fans is considered to be 14 degrees, which provides the most airflow; the best materials for fan blades are laminates (as opposed to solid wood), because of their strength and resistance to warping.
Choose the Right Size for Your Space.
Here are some general guidelines on choosing the right fan size for your space:

50 square feet (hallways, powder rooms): 29" fan
75 square feet (breakfast nook, utility room): 36" fan
100 square feet (small kitchen or bedroom): 42" fan
225 square feet (kitchen or bedroom): 52" fan
400 square feet (living or family room: 56" or larger, or two 52" fans
400 square feet: Multiple fans are recommended.
You'll also want to consider the shape of the room. For very "long" rooms, you may want to consider using multiple fans for the best air movement, even if the space is less than 400 total square feet.

Accessorize Your Ceiling Fan. Some fans are sold in individual parts, while others are all-inclusive. Whether you'd prefer the flexibility of customizing your own design or the convenience of an all-in-one package, is up to you.

Fan Downrods are usually sold separately, and allow you to provide optimal airflow in your space (particularly for high ceilings). At the other end of the spectrum, "hugger" kits allow you to fit your ceiling fan to fit low ceilings (many fans come equipped with these, so check before you order). Fan remote controls and wall controls offer added convenience.

It is important to remember that most fan accessories are made to fit a particular brand only, and are not compatible with others.

Our American Lighting Association-certified professionals at LightsOnline.com would love to help you choose a ceiling fan to enhance your home! In our huge selection of affordable ceiling fans, we offer today's top brands like Savoy House, Hunter Fan Co., Casablanca Fan Co., and Minka-Aire. We also carry a wide range of fan accessories! Visit today to select and purchase the perfect ceiling fan for your space.

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Ten Quick Tips For Choosing an Extractor Fan

1. Choose the right basic technology: Extractor fans come in two main types: Axial and Centrifugal. Axial fans are best for small rooms with small duct runs of less than 2m. Whilst they can be used on duct runs up to 5m the efficiency will be impaired. Centrifugal fans should be used when the duct run exceeds 5m or when a high extraction rate is required.

2. Calculate the correct required extraction rate: Extraction rate is calculated using the following formula:

Performance in m3/hr = Room Volume x Number of required air changes /hr

The following table shows number of typical air changes:

Domestic Environments:

Bathrooms & shower rooms 3-8

Toilets-domestic 3-10

Kitchens-domestic 10-15

Utility rooms 15-20

Bedrooms 2-4

Halls & Landings 3-5

Garages 6-8

Commercial Environments:

Meeting rooms 4-8

Offices 6-8

Restaurants & Bars 6-10

School rooms 2-3

Canteens 8-12

Shops 8-10

Changing Rooms with showers 15-20

Toilets-public 10-15

Workshops 6-10

Hospital rooms 4-6

So, to take an example of domestic bathroom: 2m x 2m x 2.5m = 10m x 8 (room changes) = 80m3/hr

3. Examine the fan's technical specifications: You have just established that you need a fan capable of extracting 80m3/hr. But this information has no worth if you don't use it to choose the correct fan. If a manufacturer or supplier does not state a fan's extraction rate then it's probably because they have something to hide! As a rough guide, 4 inch axial fans range from between 75m3/hr at the lower end to 95m3/hr at the very highest.

4. Understand the bathroom zoning system: UK bathrooms are divided into four separate zones. If your fan is to be situated in zone one or two then it must be either an SELV 12v or IP*5 rated. If it is to be installed in zone 3 then it can be a standard mains (240v) fan.

5. Take noise level into consideration. Far too often domestic purchasers look only at a fan's extraction rate. This is just one metric by which a fan should be judged and a noisy fan can become a real annoyance. These days there are so many quiet fans and silent fans available that this doesn't need to be an issue. A good quiet or silent fan will operate around 24dB(A). At this level the fan is virtually silent and will not disturb anyone while others are answering a call of nature in the middle of the night!

6. Don't forget aesthetics! For some it's the first consideration but others completely forget about how the fan will look once in situ. In the last five years designs have changed: the old slatted front grille or louvre, whilst far from obsolete is not as common as in the past. Many fans nowadays utilise a solid front panel, resembling a tile extracting through the side vents. Others use an 'opening eye' front louvre for a really cool look.

7. Think about how you want the fan to work: Extractor fans can be switched on and turned off in a variety of different ways, including: via the light switch, integral pull cord, timer, humidistat and PIR. These methods have been designed to accommodate different lifestyles and needs. For example: If your bathroom has lots of natural light, or if you are a landlord letting a property you should consider installing a fan with humidistat. This will turn the fan on when relative humidity reaches a pre-set level meaning steam is extracted even when the user forgets to turn the fan or lights on.

8. Fans with timers, humidistats and PIRs require three core and earth cable which includes both a switch live and permanent live. Such that the fan always has power going to it, but will only turn on/off when the switching mechanism is triggered. If you are replacing an old fan, it is important to remember that unless your existing fan has a timer you will not be able to use a timer on the new fan without changing the wiring because your existing standard fan will have been wired up with two core and earth cable.

9. Ducting! It seems so simple, how could you get ducting wrong!? Firstly, avoid, if at all possible, putting bends in your duct run. Bends and kinks will increase the resistance in the duct impairing the fan's performance. Secondly, use duct clamps. These secure the duct to the spigot of the fan and external grille preventing any extracted air escaping into the duct void.

10. Don't forget the back draught. By virtue of the fact that you are connecting the outside world to the inside of your home via a four inch pipe you are potentially going to suffer from chilly back draughts. Whilst easily prevented these are often overlooked and once the fan is installed much more hassle to remedy. Some fans these days come with integral back draught shutters, but many don't so either fit an inline back draught shutter which sits in the length of ducting or fit a gravity grille on the external wall.

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