Answers

1.  Add insulation in walls and roof.  2.  Air seal your home. 3.  Install Low E or better dual pane doors and windows.

When it comes to energy efficiency, adding insulation is the most affordable upgrade that can be done to a 2-story home. With good insulation, there will be an immediate return on the money spent. A high performance energy efficient heating system is also very important. Energy efficient heating and good insulation work hand in hand by paying the homeowner back hundreds of dollars a year, along with the home being much more comfortable to live in. Lifetime aluminum metal roofing should rank very high on the priority list for an energy efficient home; certainly among the top three upgrades. The product itself is made from a very high percentage of post consumer aluminum. It is also considered to be among the most long lasting sustainable roofs that can be put on a home.There are aluminum roofs that are well over 100 years old in the USA. These roofs have very high reflectivity, which equates to high energy savings during the summer months or in the south where air conditioning is needed. These energy star rated roofs can save as much as 30% on energy as it relates to cooling costs. With proper insulation, energy efficient heating, and metal roofing, the home will have optimum energy efficiency and continue to remain at the most comfortable temperature based on the given seasons.

The first thing to reduce energy is to see where it is being wasted.

 An energy audit with blower door test and infared camera is the best place to start. 

 The list of upgrades range from adding insulation, to replacing HVAC systems and everything in beteen, such as new windows and doors to installing smart theromstats. But because each home is different and has different needs the only way to be sure your upgrades are right for your home is to start with an energy audit.

I have yet to survey a home that didn't need additional insulation and more importantly....air sealing. 

While HVAC systems are typically older in most homes that we audit, every home that I have ever been in leaks too much air and much, much more than is required.

Air Sealing and Insulation would be #1 and #2 on my list.  After that, items like HVAC and windows will jockey for position depending on the condition of both. 

Before you do anything new...look at what is already there. 

1. Do the existing windows allow drafts?  Upgrade existing windows first before considering new windows.  I don't think the payback is that great over existing windows that are properly maintained. 

2. Is the header serviced annually?  Change the filter monthly (there are so cheap), check all the ducts for breaks and tape them up.  Walk around the house when the heater(s) are on and check the temperatur in each room.  When you have done your homework then have a profeswsional come in.

3. Seal around the ceiling can lights on the second floor that are allowing heater air into the attic. 

4. Replace the seal around all your exterior doors.  This is really the case on the door from the garage to the house. 

Start there \Philp Anderson HDR Remodeling Berkeley CA

Step one, if you have siding use a insulated vinyl siding with silica gel. Replace your windows with a double or triple insulated window system. And third your doors are very important. When you do replacement anything you want the doors and windows to fit the space perfectly. We can do these things and more at Jarrett Industries.

We have written on good bit on this subject: Please take a look at these blogs we wrote!

http://blog.akatlanta.com/2010/11/10-mistakes-not-to-make-when-heating.html

http://blog.akatlanta.com/2010/11/7-winterization-tips-to-keep-your-money.html

John Ford, There are an abundance of energy efficiency upgrades you can do to your 2-story home. A question to your question - do you have a small or a larger budget? Small budget - 2 options: Attic Insulation or A Foil Energy Barrier, one example is Green Energy Barrier. Blown-In Attic Insulation is inexpensive and can help with an additional R-value of 18-60 in your attic. A Foil Energy Barrier - can be placed along the rafters or floor boards and is a foil used by NASA that greatly assists with energy efficiency. Larger budget - 3 solid options: Solar panels, Replacement Windows with Krypton gas, or Insulated Siding, an insulation with a system R-value of a 4.2 that contours to your siding panel. Best, Ken 

Many great answers here regarding insulation and air sealing.  If you have a pool, also look into upgrading your pump to a variable speed pump.  They run at lower RPM for filtering than they do for vacuuming.  This can be a significant saver in energy costs... and as always, GO SOLAR!

Solare Energy has been serving San Diego for 25 years and provides our customers with a free energy audit and rate analysis before designing a solar panel system for their homes.  This allows us to accurately size the system to your energy consumption needs and get you the best value for your investment.

Learn more at www.SolareEnergy.com or call 858-547-4300 for San Diego area solar installations.

Rob Shaw
Marketing Manager
Solare Energy, Inc.
San Diego, CA

For both an existing and new construction home, the top three items that provide the greatest value and return on investment are as follows:

1. Installation of LED light bulbs and fixtures in replacment of incadenscent or compact flourescent bulbs/fixtures.
2. Sealing of exterior shell of house and all top plate penetrations in conjunction with blower door test.
3. Properly installed insulation in walls and ceilings and upgrading R-Value above code requirements.

Additional items to consider include:

1. Testing and sealing of hvac system duct work
2. Upgrade hvac system condenser SEER and furnace efficiency
3. Tankless water heater
4. Solor photovoltaic system

Great insulation plays a key factor in energy savings. There are many different options available to increase the energy efficiency of your home.  James Hardie Siding is specifically designed for the climate in which it is installed. Whether you live in a climate with freezing temperatures, snow & ice or a climate with high humidity, heat, and rain; James Hardie has a siding product built for your homes specific needs. Technology has changed tremendously over the years so homes built 15- 20 years ago may have been installed with what was considered cutting edge at the time. Window replacement and the new technology that windows have now can save a great deal of energy costs. A good product that we can recommend also would be the Mezzo Vinyl Window or Integrity by Marvin Windows. These are high performance windows that are engineered to provide outstanding energy efficiency. Major appliances such as heating and A/C units can also offer great energy savings. 

Oftentimes the attic is the place to start.  Make sure you have plenty of ventilation, both intake and exhaust.  Check the soffit cavity to make sure you it isn't clogged with insulation.  There are formulas for Square foot of attic in relation to ventilation.  If you have a vapor barrier in the ceilling a ration of 1:300 sf is ok, otherwise about 1:150 is the rule. Second, check the insulation.  All air escaping into the attic should be sealed using spray foam or other sealants. Next, depending on your geographic location, make sure you have plenty of insulation in the attic.  Finally, something as simple as installing blinds over windows can be an economical solution to saving on energy costs.  As recommended in some of the other answers, an energy audit or getting advice from any number of qualified professionals that are willing to visit your home is the best place to start.

The energy efficiency of a home relies on several factors. 

The most dominant of these factors is the insulation used, both within the perimeter walls and attic.  This would include the houses ability to breath as well as maintain a good barrier.  It's not so much the amount of insulation as the type and installation methods.

Another factor that effects the energy efficiency of your home is your windows and doors.  They come in all varieties of energy ratings, and are also reliant on the installation methods used.

The third thing that I would look at is the ventilation of your attic.  If your attic has the necessary ventilation needed it can reduce energy cost as well as prolong the life of your roof system.

I say insulation should be at the top of your list. I would also take a look at your water pumps.

Here's a few of the items we actuallyp ersonally suggest when going green: http://xtremegreenhomes.com/green_options.php.