What Is a Zero Energy Home?

In this day and age of growing awareness of conservation of energy and a more holistic approach to building, one term that you may hear from time to time is "zero energy home."  It may sound impossible, but there really is such a thing, and more and more people are striving to attain this ideal when building a new home. So just what is it? A zero energy home (ZEH) is one where all of the energy needs for the household are supplied by alternative means. It does not mean a home that uses no electricity. Solar panels and solar water heating systems are generally the form of energy employed by these homes, because they are residential. Residential wind turbines are uncommon in most community neighborhoods - at least so far.

Solar boiler on a rooftop. (Photo credit: Wikipedia)

A zero energy home needs some sort of back-up. It is often not actually an "off the grid" home. The sun is not always shining, and sometimes a home's energy needs drastically increase for a variety of reasons (a cold snap, a heat wave, or an increase in laundry). In fact, zero energy homes remain connected to the utility grid, and often engage in net metering.

Net metering means both the energy you use from the grid and the amount you put back into the grid are measured. Because an electric meter can spin forward or backward, the homeowner gets credit for the energy he or she puts into the grid, which is a good safeguard against those times when you need back-up.

How a ZEH Works

As noted above, a photovoltaic solar power system is employed for electricity generation. Water is heated by a passive, solar-thermal system. Passive systems do not use electrical energy to warm the water. They simply collect the sun's heat and use it to warm water. Energy needs are greatly offset or replaced for heating, cooling, lighting, and appliances.

draft of a solarpipe (Photo credit: Wikipedia)

What Else Is Involved In a ZEH?

Some ZEH builders use awnings over the windows and large eaves to block hot summer sunlight but let in sunlight in the winter. Windows in a ZEH home are thick, as is the insulation. Skylights supply much of the indoor light and the solar panels are on the roof, so the angle and location of the home are carefully considered by the builders.

How Do You Obtain a Zero Energy Home?

There are professional builders that specialize in or include the construction of zero energy homes.

You could also take a DIY approach and convert your existing home into a zero energy home. But, although in theory, a conventional home could be converted into a ZEH, the essence of a ZEH is that it is constructed from the ground up. This is because the designers incorporate a lot of "tricks" and design elements within the house's walls, roof, and so forth that would be impossible to insert into an existing home. But you can still achieve great energy savings by incorporating some of the principles of a zero energy home into your existing home if desired.

How to Choose the Right Solar Power System for Your Home

With energy costs rising steadily, more and more people are seeking ways to incorporate solar power into their energy plans for their household. However, there are some things to bear in mind if you want to install a solar power system in your home. Not just any system will do. It needs to fit your energy needs and your property location. Here are some tips.

First, determine if your location is conducive to solar. You need to have an area of your property that faces in a southerly direction - ideally, it will face directly south, but slightly southwest will work. It needs to receive sunlight between 9AM and 3PM. Make sure you observe this area all year round, because a property's sunlight can vary greatly from season to season.

Remember, too, that you can mount solar panels on tall poles and trees, not just your roof. So if an area of your property is shady during the key part of the day, look up - it might be sunnier up higher.

Second, call your utility company and find out what your average monthly use of kilowatt hours is. Then you can determine how many KW hours your solar system will have to generate. (You might choose to have only half of your KW hours replaced by solar.)

Types of Home Solar Systems

In order to narrow down what sort of system you need, it's important to familiarize yourself with the different types. Most homeowners choose to be tied in to the power grid, because a stand-alone system can get very complicated and expensive. It is an option, however.

Flat-plate solar thermal collector, viewed from roof-level (Photo credit: Wikipedia)1. Photovoltaic solar panels
These are what most people think of when they think of solar power. They are flat panels that sit on your roof. Generally, photovoltaic systems can power appliances and lights only, not heating and cooling.

The power generated is usually tied in with the conventional power grid, and this is viable option for most solar power users. If you are tied in to the grid, you do not need a battery back-up for night-time and other times when the sun is not shining. The conventional power company becomes your back-up when you are tied to the grid.

2. Solar heating systems

There are active and passive solar heating systems for our home. Passive solar heating uses conduction, convection, or radiation to move sun-generated heat throughout the home. Active solar heating collects the sun's heat in some kind of air or water reservoir, then pumps it throughout the home.

Obviously, depending on the system you choose, these are usually less costly and easier to set up and maintain than a solar panel system. You may choose to go less intensive and just use passive or active solar heating, or you may add solar panels as well and reap the benefits of a combination of these systems.

For a great resource for both solar D.I.Y. info, and pre-made solar power system kits, check out Solar Sphere's website.