About a year ago I bought a Nest programmable thermostat with the expectation it would eventually save me money.  Since I already had baseline data with my original “dumb” thermostat, it took me about a year to get good comparison data with the new thermostat.  As I have historically done I recorded the electricity used each day and matched it up to the average temperature recorded by the weather service at the closest airport.  This was then used to derive a formula for daily energy usage versus average daily temperature.  These curves are primarily a function of the size of my house, the efficiency of my heating system, my house’s insulation, and the setpoint of the thermostat  (The thermostat is typically set at 70°F with the new thermostat allowing the temperature to be set back in the winter  to 65°F at night and when no one is home.)  As expected when it’s colder outside it takes more energy to heat the house.  The same thing happens in the summer, the warmer it is outside the more energy it takes to cool the house. 

 

The next chart shows the average monthly cost for my location based on the above curves.  It also includes assumptions for the average monthly temperature at my location and the cost of electricity at my location.  January is the highest cost month with its low winter temperature.  May and September are the lowest since they are between heating and cooling season.  July has a small increase due to air conditioning costs.  Notice how insignificant summer cooling costs are versus winter heating costs at my location!

 

So how did my thermostat turn out?  The difference between the blue and red lines is $77 per year.  Therefore it’s going to take over 3 years for the new Nest thermostat to pay for itself.

One thing I’ve always wanted to know is, what is the ideal speed to drive your car for maximum fuel efficiency?  Obviously aerodynamic drag is going to decrease fuel economy at higher speeds, but I always suspected there was a speed point below which other factors also reduced fuel economy. 

In the past I had tried recording long drives and then plotting instantaneous fuel economy versus vehicle speed, but I always suspected the data was being corrupted by coasting and accelerating.  The lower speeds tended to be either accelerating or coasting while faster speeds tended to be primarily steady state cruising.

To rectify this I found a stretch of road on the way home from work with minimal traffic so I could vary my speed without being a traffic hindrance.  Each day I drove the same stretch of road at different speeds using the cruise control.  I used the Torque app on my phone with a Bluetooth adapter connected to the car’s OBD port to record the fuel economy and vehicle speed.   Since the software can also use the phones GPS I was able to only use data that was recorded between specific latitude points so the same start and end points were always used.

As can be seen in the chart below my particular car appears to have the best steady speed fuel economy at about 35 mph.  I suspect some others factors are probably included in this data, with the largest suspect being ambient air conditions, probably air temperature or possibly humidity.  After I get some more data over a whole year I plan on making separate curves for different temperature ranges.

Home Electricity Useage

As collector of data (hoarder?  I doubt my cluttered hard drive will ever be featured on a TLC show) one of the things I've always saved since living on my own is the electricity usage and cost I use every month.  It was easy since the electric company would conveniently send it to me every month and save it on their website.  Below is my monthly usage for the last decade or so.

The blue line is my original house with electric resistance cable heat in the ceiling.  The red line is the new house which is larger in area, but better insulated with 2x6 exterior walls and spray foam insulation, and geothermal closed loop heating system.  The houses were within 5 miles of each other so both were in the same climate.  Some trends here are pretty obvious, in the winter when it's cold out and you use electricity for your heat source you're going to use a lot more of it. There's also more light usage during the shorter days, but I think most of the difference is in the heating.  Also the new house has about half the winter usage, but is similar in summer usage.  What happened in 2005 when summer usage doubled?  That was when I got married and was joined by my beautiful wife in the house who apparently uses about 500 kWH per month by herself.  (As a side note if you make similar measurements don't bring it up, your spouse will not find it interesting).  There may be some winter effects of keeping the house warmer than I did by myself in there too (Also a touchy subject).

Cost is a similar story although you can also see the gradual rise in energy costs over the years.  I heard a lot of horror stories before I bought the house about the cost of electric heat.  Although it was by no means cheap, I don't think it was much different than most people's natural gas bills in the area.

 Where does all the electricity go?  To find this I used two devices, a killowatt plug in meter and for devices that are hard wired The Energy Detective (TED).
http://www.p3international.com/products/special/P4400/P4400-CE.html
http://www.theenergydetective.com

Not surprisingly home heating was by far the largest user of energy even with the geothermal system, next came the clothes dryer,hot water heater, and than an old chest freezer we have in the garage  all around $10 per month each.  One surprise was a water cooler fountain we were using in the kitchen, it was making both hot and cold water (although both in small quantities) and cost nearly as much to run as the freezer and more than the kitchen refrigerator. Things like the computer desk, television, and oven were in the $5 per month range.  Commonly used lights tended to be a dollar or two per month.  I'm careful not to leave any lights on 24 hours a day or overnight, as that would start to add up quickly especially if they were 100 watt floodlights like you commonly see.  Occasionally there will be news articles about "vampire" loads in cell phone charger power supplies.  These things cost pennies a year, you can worry about them if you think it will help the environment, but they aren't going to save you much money.  Use your money for better insulation or a more efficient furnace.

Here's an interesting chart showing how the outside temperature effects the cost of running the furnace or air conditioner.  Obviously the colder or hotter it is outside the more energy it will take to maintain the indoor temperature of the house.  A side affect of the furnace or air conditioner running often is it will start using the desuperheater to heat the water going into the hot water heater.  In the summer this is pretty much free energy it is taking out of the indoor air.  In the winter it isn't quite as good deal, but it's still more efficient than the straight resistive heating of the conventional water heater.  So the result is the more you pay to heat and cool the house the more you save on hot water.  It never will pay for itself, but it is substantial.  Once it gets below 20F or above 90F I'm pretty much not paying to heat any water.

Multiport Sequential Electronic Fuel Injection Retrofit for V8 Engine

This project builds off of my previous experience of updating carbureted Ford engines with late-model Ford fuel injection systems.  The vehicle used for this build was a 1977 International Harvester Scout II with an International Harvester 345 V8 gasoline powered engine. 

The use of an orphan vehicle (ie made by a manufacture who no longer engages in the manufacturing of light duty vehicles) presented added complication in that modern parts are not readily available.  Of particular importance in fuel injection control is being able to find a distributor that allows for electronic control of the ignition timing.  Although IH did do some development work in the early 70's on both mechanical and electronic fuel injection nothing was ever released for production.

Since my previous experience had been with the Ford EEC-IV system modified with a Tweecer from STKR.  I found the EEC-IV with Mass-air sensor adaptable enough to make the changes I needed but simple enough to not require excessive hours of tuning.  I also needed the real time data logging of the RT model.
http://www.tweecer.com


To overcome the distributor hurdle I investigated using a distributorless ignition system (EDIS) found on the later 4.6L engines.  Luckily the EEC-IV was able to adapt to this.  It required installing a crank speed sensor, which I installed spaced out from the front of the damper.  Later I saw where someone had mounted a similar sized toothed gear behind the damper which was a prettier solution, although at the time I didn't have access to the machining tools needed to do such a thing.  Since the oil pump was driven by the bottom of the distributor I had to leave the bottom half of the distributor installed.  The coil packs were mounted on top where the cap originally was.

The intake also presented a problem.  The cast iron intake obviously did not include provisions for mounting  modern fuel injectors.  It did conveniently have extra material on top of each intake runner that I assume was part of the casting process.  These were leveled off with a grinder and then drilled for each injector.  Matching fuel rails were made and mounted to where the carburetor previously mounted.  An aluminum elbow was then mounted in place of the carburetor which was connected to the throttle and MAF sensor.

Getting it to run was fairly easy.  It would run with the base Mustang calibration although not well as there is a significant difference between the higher revving Ford 5.0 HO and the slower more torque oriented IH 345.  Once the MAF calibration was adjusted to account for the heavily modified intake system, it ran pretty well.  Much better than I've ever gotten a carburetored 345 to run.  Fuel mileage was in the mid teens, which isn't great, but you can only do so much with such a heavy block of a vehicle.