I would start with making sure your attic has adequate ventilation. 

Verify that all window and door seals/weatherstriping is in good shape.

Check to be sure doors and windows are caulked properly (no gaps, cracks or missing).

If you have an attic access, treat it like door opening and seal properly. If possible, create an insulated cover to go over it in the attic.

Check HVAC ductwork for leaks and seal with foil tape or mastic.

Wrap your hot water heater in a blanket.

The most cost effective things that you can do to improve your homes energy efficiency will depend on the existing condition of your building envelope, the efficiency of your equipment, and humiditiy control.

Addressing the condition overhead and tightening the building envelope are basic principles involved in maintaining efficient temperture control in the home. Thermal imaging will clearly indicate areas of major heat loss.

There are many types of structures and styles of thermal barriers. Therefore, you are best advised to have an energy consultant from a Home Energy Rating Service HERS evaluate of your particular home and assist in identifying the weakness of your home envelope and machanical equipment. Such a report  can provide you with a roadmap to begin taking steps to improve the overall efficiency of the home. 

Air sealing and insulation are the two biggest things you can do to globally improve the efficiency of the home. 

There are several articles on this application and I have yet to be in a home that didn't need it. 

Tightening up the envelope across the attic surface will lessen air infiltration at all the other areas of the home. 

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

John,

There are options available to go solar and be completely independent of you local utility provider. However, this type of set-up (solar+storage) is much more costly than the traditional "grid-tied" system mentioned by Mr. Cook. There are significant developments in the works for the energy storage industry and speculation suggests that batteries will become more reasonably priced in the next 3-5 years or so.

Until then, many folks are opting to install a grid-tied solar panel system, which can often offset 100% of your utility bill (minus a nominal monthly interconnection fee of $5 or so). In some cases, fully offsetting your electric bill isn't possible because of shading or roof complexity. When battery storage becomes more affordable, you can add storage and truly become energy independent!

Hello Alex, 

One alternative that most homeowners are not aware yet is reviewing your Roofing System. Along with the attic insulation, the type of roof you have can make a huge difference on how energy efficient your home is.

Most roofing materials (especially asphalt composite roofs) absorb solar energy and transfer heat to your home (requiring more air-conditioning during summer). On the other hand, energy efficient Metal Roofs are reflective and emissive. They bounce most of the sun's visible and UV light - meaning less heat transferred to your home. Independent studies show energy savings of up to 25%.

The Interlock Metal Roofing System is Energy Star certified (US only). More than energy efficient, our roofs are truly sustainable, being made of up to 95% recycled material, reducing the dependence of asphalt and stopping the cycle of old roofing material going to landfills. It is a lifelong solution that is better for your home, your pocket and the planet.

Solar shingles are expensive and unproven.  I recommend Sun Power photo voltaic solar.  An average home is $20,000 to $30,000 and the return on investment is 4 to 6 years on a 25 plus year system.

Solar panels are a great "green" addition to any home. That said, the roof underneath the solar panels is just as important. With an asphalt roof, the homeowner is going to be removing the solar panels to replace the asphalt roof long before the solar (PV) needs to be replaced. This wise choice would be to install a lifetime aluminum energy star rated roof and attachthe PV solar to the new metal roof. When the PV needs to be replaced or removed the roof will still be in service. In fact will last for many years beyond the life of the solar panels. On a different note, if you decide to install solar be sure you have a landing area for the snow slides coming off the panels. It is a little known problem that is just coming to light by the industry. Snow slides coming off a roof with solar can cause significant damage or injury. Be sure to address this issue with your solar contractor.

+1

If you can amortize it into the long term loan on the home, it is a 100% no brainer.

Yes!!

Alex, the region you are in is crucial and consider the cost vs time of recapitization