Refrigerator Analysis

 

Our current refrigerator is a GE Profile 24.7 ft^3, model number TBX25PAB that was manufactured in March of 2001.  As part of our Half Project, I was interested is seeing how our refrigerator (which is not Energy Star rated) compared to a newer model refrigerator and to see if it made sense to upgrade.

The power consumption of the current refrigerator was measured with a Kill-A-Watt meter over the course of several weeks at 2.4 kWh/day, or 876 kWh/year.  For our area, Dominion Power charges us approximately $0.11/kWh, so our cost to run the refrigerator is $96/year which is about 3% of our yearly energy consumption.

The Energy Star website has a refrigerator/freezer calculator that you can use to calculate the operating costs of your current appliance.  I used this to compare the actual usage data that I collected with the estimated usage from Energy Star.  The chart below shows that the estimated usage is slightly higher than my actual usage, but it is within 10% which is acceptable for an estimate.

Model	Data	kWh	$/kWh	Per year cost
GE TBX25	Actual	876	0.11	$96
GE TBX25	Estimated	961	0.11	$106

 

GE makes a newer version of the Profile series which is a direct replacement for what I currently have.  It is a little pricey at $1800 but let’s look at its performance.  First of all I’ll ignore the fact that the Sears website has conflicting data with the Energy Star label over yearly kWh usage and I’ll just use the data from the Energy Star label. 

Model	Data	kWh	$/kWh	Per year cost
GE PTS25	Estimated	560	0.11	$61

Using the Energy Star estimates for both the old and new refrigerator I can expect to get the following savings.

Energy Saving/year	401 kWh
$’s Saved/year	$44.11
Initial Cost	$1800
1st year Return	< 2.5%
CO2 Reduction	441 lbs

With a payback period of ~40 years, upgrading to the newer model GE Profile just doesn’t make sense right now.  It’s time to research other models of refrigerators.

Crawlspace Insulation Fail

I recently did a full survey of all the insulation in my crawlspace. I've been under the house on several occasions before but I never really looked at the insulation other than to say "yep, there's some there."

I'm not really sure what inspectors look for before signing off on the different phases of construction, but I have a feeling that when it comes to insulation and crawlspaces, the inspectors just ask the contractor if they insulated the crawlspace and if the contractor says yes, then it passes inspection.

Armed with a flash light and camera I dove in to see what I would find.  Below are a few of the flaws/shortcuts that the contractor took. 


On the north side of the house, there is a just a partial floor joist bay between the band joist and the first floor joist.  Since this is an odd size the easiest thing to do is not install any insulation.

Whenever there are pipes in the way, obviously the best thing to do is to push all of the insulation to one side. 

When you encounter duct work, you must not install any insulation above it.  No one is ever gonna look up there anyway, right?  And when you do put a section of insulation in, you should grab a piece that's 16" wide even though the engineered joists are on 19.2" centers. 

When you get to the end of a roll and you're 12-14 inches short of making it to the end of the joist bay, it's probably good enough.   On the east side of the house, every single bay was short by about a foot.  Lovely...

On the left side of this picture the exterior wall makes a 45 degree turn and runs right into "it's Miller time".  The end result is a three foot gap.  Notice that the insulation isn't pushed up tight against the sub floor either.  This allows cold air to get another 6-8 feet further in before it finds an insulation hanger that is properly installed.

Changing The Thermostat - What Affect Does It Really Have?

The Home Monitor that I built has been collecting data for several months now and I decided to look back at some of the data that was collected on how often my heat pumps come on and which zones are calling for air the most.  In particular I was interested in knowing what affect different thermostat settings had on how often the heat pump came on.

To do this I looked at a single zone on the upstairs heat pump that controls the temperature for the two guest bedrooms.  During this past summer when the guest bedrooms were not in use the thermostat was set to 80 degrees.  When we did have a guest using one of the bedrooms, the thermostat was set to 76.  The rest of the house is set to 76.

I then went through the data for the summer and collected information on 6 days where the outside temperature and attic temperature were roughly the same.   On half of those days the guest bedrooms were not occupied and the thermostat was set at 80.  On the other half the bedrooms were occupied and the thermostat was lowered to 76.

Below are the graphs for the attic and outside temperatures during those 6 days.  The data graphed in red is the attic temperatures, blue is the outside temperature.

Daily temps with guest rooms unoccupied.

Daily temps with guest rooms occupied.

The data for the guest bedroom zone was then graphed (shown below) when the thermostat was set to 80 degrees.  Average run time for the three days was 123 minutes per day.  Note that the zone typically didn't call for cooling until late in the day when the outside and attic temperatures were near their maximum.

Thermostat set to 80

The data for the guest bedroom zone was then graphed (shown below) for days when the thermostat was set to 76.  Note that the zone calls for cooling throughout the entire day and that by the time the hottest part of the day arrived, the zone had already been calling for cooling for over 200 minutes.  Average run time for the 3 days was 560 minutes per day.

Thermostat set to 76

What did I learn from this?  There was a 78% reduction in the time that the zone is calling for cooling when the thermostat was set to 80 instead of 76.   Installing a programmable thermostat and actually programming it (instead of just pushing the "hold" button), can have a dramatic affect on the amount of time your hvac system runs.

End of Summer Update

This summer was a very good test of the changes I have made to reduce my energy usage.  Although it was hot, it wasn't quite as bad as last year.  The degree days show that it was well above average and slightly less than last year.    I did make a few changes in addition to the changes I made earlier in the year that were detailed here.

It is so humid here during the summer that it's very rare that we ever open the windows.  All of my windows are casement windows that have the bug screen on the inside.  So the first change was to remove all of the screens and store them away until early Fall when we start to open the windows again.  The reasoning behind this was all of the testing that's been done on solar air heaters using window screen as the absorber material.  If it's that good of an absorber, I need to just get it out of the way and let the shade reflect as much light and heat back out as it can.



The second change was to make better use of my programmable thermostats.  They have very specific schedules set to them now and in addition, the two guest rooms now have their dampers mostly closed on the days that no one is here using them.

The end result of this is some excellent news!  At least my wallet thinks so.   The total KWH usage for the months of June - Aug was down 4,255 kwh over last summer and the total bill for was down $365.  So far for the year I'm about 9,000 kwh under the usage of my six year average.



A Home Built Heat Pump / Energy Usage Monitor

A couple of years ago I bought a small robot kit for my kid to experiment with from a company called Parallax.  Along with the robot I bought a couple extra of their Stamp chips just to play around with.  After a couple of months the "this is interesting" factor wore off and I moved on to something else.  Last summer (2010) after working in the attic one day I wondered how hot it got up there and thought about the possibility of putting a temperature sensor in the attic that I could monitor remotely.   Already having a BS2P from Parallax on hand, I connected a Dallas Semiconductor DS18B20 to it and wrote a small program to log the data to my PC every 15 minutes.   After a few days, I started wondering how the outside temperature affected the attic temperature and added some more code to log the outside temperature as well (a year worth of data is here at BuildItSolar).  I then added an additional sensor in the crawl space and not knowing where I was going with it, put the project on the back burner.

The Birth Of My Home Monitor

In Dec 2010 I ran across BuildItSolar and Gary's Half Program and I soon knew where I was going with those few temperature sensors.  The project needed to grow.  A lot.  After looking at a couple of options for chips/circuit boards to monitor multiple 1-wire temperature sensors, I decided to just keep on using the Parallax BS2P's since I had them on hand.  Personally, I've not used the Arduino yet, but from what I've read I'm sure it would be more than capable of doing what I've implemented. 

What I'm Monitoring

I now have 16 temperature sensors installed around the house with most of them monitoring what my two Water Furnace ground source heat pumps are doing.  Here's a run down of where the sensor are located:

Upstairs	Logging Time
Attic	Every 15 minutes
Outside	Every 15 minutes
HP Supply Air	Every 1 min when HP On
HP Return Air	Every 1 min when HP On
HP Desuperheater Out	Every 1 min when HP On
HP Desuperheater In	Every 1 min when HP On
HP Earth Loop Out	Every 1 min when HP On
HP Earth Loop In	Every 1 min when HP On

Downstairs	Logging Time
Crawl Space	Every 15 minutes
Hot Water Tank	Every 1 minute
HP Supply Air	Every 1 min when HP On
HP Return Air	Every 1 min when HP On
HP Desuperheater Out	Every 1 min when HP On
HP Desuperheater In	Every 1 min when HP On
HP Earth Loop Out	Every 1 min when HP On
HP Earth Loop In	Every 1 min when HP On

I also have 7 sensors that detect when the different zones for each heat pump come on.  The upstairs heat pump has 3 zones and the downstairs heat pump has 4 zones.  Detecting when the heat pumps are on allows me to log the heat pump temperature sensors only when they have meaningful data.

When I received and installed my TED 5000 in Jan 2011 I quickly found out that the load profiling software didn't work quite as well as I wanted it to.  To fix that problem I added the ability to retrieve all of the "seconds" data from the TED 5000 and save it to disk and I wrote my own functions to do the load profiling.  Since I have all the data locally now, I generate all the usage graphs within my monitor program and rarely look at the TED web console anymore.

I now have a fairly complete energy picture of my house and can see not only how much electricity is being used and what's using it but can also see how well things are working.  It also gives me the ability to log some baseline data so that when I do make changes I can actually see if it makes a difference.

A Flatlined Hot Water Tank

One of the projects that I've been considering implementing for the house is a water based solar space heater similar to the $2K System that Gary over at BuildItSolar installed.  The basic idea is simple, gather heat from the sun during the day, store that heat in a large water tank, and distribute that heat into the house when needed. One of the issues that needs to be resolved before I jump in and start construction is what to do with all that heat during the summer.   From what I've seen on BuildItSolar and on the SimplySolar yahoo group is that most people use these system for both space heating and as a pre-heater for their hot water.  I would like to use all of the heat during the winter for space heating, but during the summer when I could make hot water, I wasn't sure that I needed it.  I suspected that my ground-source heat pumps with their desuperheaters provided all (or nearly all) of my hot water during the summer.  If that's the case, then my ROI would be significantly lower as the system would only be used during the heating season and would be stagnant for all of the cooling season.

Testing the desuperheaters

To find out if the desuperheaters could handle the entire DHW load I ran a couple of tests.  The first one was simple... turn off the hot water heater at the breaker.   After a short prayer service, the switch was flipped and the hot water heater flatlined at noon on May 24.

The graph above shows that the hot water heater really has been off for the last month.  The tank temperature seemed to be ok as all of the showers continued to be hot.  But to be sure, the second part of the test was to install a temperature sensor on the hot water tank.   The sensor is a DS18B20 and is installed against the inside tank wall underneath the insulation near the upper thermostat.  The sensor readings were spot on with the temperature of the water that I was drawing out of the tank, so now it's just a matter of logging the data every minute and graphing it.

The manual that came with the Water Furnace heat pumps says that the desuperheater circuity kicks out at 130F so I should never see tank temperatures above that.  The 5 day graph above shows that the tank temperature slowly drops during the early morning when the heat pumps run infrequently, but the temperature recovers nicely during the day and if it gets above 90 for any length of time during the day, there's a good chance that I will max out the tank temperature.  The big dip during the day on the 26th was a shower immediately followed by a bath just to see what would happen.

What I've found from this is that my desuperheaters can provide all of my hot water during the summer months as long as some thought is given to when things happen.  So, that brings me back to my original problem.  If I build a water based solar collector, what do I do with it during the summer months?

Hmm...

My Half Project: 4 Month Update

After 4 months I'm happy to say that I have not gotten bored with my Half Project, in fact I think I have become obsessed with it.   Most of the projects that I have worked on so far have been related to monitoring where I'm at with usage and making minor changes to see what affect they have on usage.

Some of the projects that I've worked on so far are:

1. Installation of a TED 5002-G Home Energy Monitor.  This has been a wonderful tool for allowing me to see what I'm using when I'm using it instead of finding out at the end of the month.  It also led to the discovery of a thermosyphon loop between the DHW heater and the downstairs heat pump that was causing the DHW heater to come on much more often than it should.
2. Purchase of a Kill-A-Watt meter.  This has been useful for determining what some of the individual loads in the house are.   Because of this, things like the printer are now on a power strip so that they can be turned off.   Like off, off... instead of the kinda somewhat off but not really off that the power button does.
3. Shades. Lots and lots of shades.   On all of the south facing windows that aren't shaded by the upstairs deck and most of the west facing windows.
4. A scan of the entire house with a Fluke thermal imaging camera.  This led to the discovery of some minor leaks around some doors and the attic entrance access panel.
5. A check of all the duct work and the repair of leaks that had occurred over time.
6. Some general conservation projects.  This turned out to have a huge impact on reducing my energy usage with little to no changes in my lifestyle.
7. A change in my driving.  I switched from using the SUV for everything, to only driving it when needed and driving the car for all my errands and trips into the city.

So what does this all mean?  It means that for the first 4 months of this year my energy usage for the house is down quite a bit from previous years and is the lowest it has ever been.

As you can see from the chart above, my usage is below or significantly below the monthly average for the first four months of the year. 

Which means that the total KWH usage for the year so far is well below previous years.  The degree days for this year have been slightly higher than for 2008 but yet I'm still 2000 KWH below the usage for 2008.

Now for the vehicles...  I thought that this would be a major area of reduction in GHG.  Switching my primary vehicle to one that gets 8 mpg more seemed like a sure fire win.  However, that victory has been hidden by two things.  First, a family members failing health has resulted in two 1,000 mile round trip visits to help out.  The whole family went which required taking the SUV.  Second, a change in scheduling now requires me to drive into the city three times a week instead of once a week at 80 miles per round trip. 



Even with all of the extra driving so far this year, I'm still equal on gasoline usage with my 8 year baseline.  

Conclusion:  The results so far have been extremely promising.  My goal was to reduce my usage by 5% per year knowing that some of the changes up front may result in drastic reductions in usage.  That drastic upfront reduction has occurred.  The minor conservation projects that I have undertaken so far will result in at least a 12% reduction in my energy usage and my electric bill for the year is down $379 (almost a $100/month) from last year.  Woot!

Conservation Projects

As part of my half project I have identified several areas where I could reduce my energy usage for little to no cost.

PCs:

I have three PC's in the house that are used infrequently (less than 2 hours per day) which used to be left on all the time.   The kill-a-watt meter showed that on average these systems used 150 watts of power.  All of the systems have now been set up to hibernate if inactive for 15 minutes. 

Energy Saving/Yr	3175 kwh
Initial Cost	$0
$'s Saved/Yr	$349
CO2 Reduction	3779 lbs

LIGHTS:

Most of the lights in the house have been converted over to CFL's.  However, there are three 75 watt incandescent floods that are in the main part of the house and are on 16 hours a day, every day.  These have recently been replaced with 8 watt LED floods.

Energy Saving/Yr	1174 kwh
Initial Cost	$66
$'s Saved/Yr	$129
CO2 Reduction	1397 lbs

Printer/Fax Thingy:

My HP PSC2510 which was detailed in a prior post has now been put on a power strip so that it really is off.  I may actually use the thing once a month.  It's pointless for it to be using power 24/7.

Energy Saving/Yr	149 kwh
Initial Cost	$3.50
$'s Saved/Yr	$16.40
CO2 Reduction	177 lbs

Phantom Loads:

A survey of the house with the kill-a-watt meter showed that several devices that are plugged in 24/7 are using power even when "off".  The TV sets in the two guest bedrooms, a CD player and treadmill in the exercise room, and the TV in the master bedroom that was swapped out for a new LG.  Individually these devices didn't use much power.  As a group, they do.

Energy Saving/Yr	203 kwh
Initial Cost	$0
$'s Saved/Yr	$22.35
CO2 Reduction	241 lbs

Water Heater:

The issues with the water heater which have been detailed here have been temporarily fixed while waiting on parts from the local hvac company I use.  The savings for not pumping heat into the garage should be noticeable.

Energy Saving/Yr	670 kwh
Initial Cost	$0
$'s Saved/Yr	$73.75
CO2 Reduction	797 lbs

Totals:

For the changes listed above, which had almost zero cost other than I just needed to be aware of what was going on, I expect to see the following savings per year.

Energy Saving/Yr	5373 kwh
Initial Cost	$69
$'s Saved/Yr	$591
CO2 Reduction	6,394 lbs

This is a significant amount just for being more aware of what I'm doing.  The energy savings of 5373 kwh is roughly 12% of my yearly consumption.

Ductwork sealing and insulation

Today was "review the ductwork" day and I'm happy to say that for the most part it was still in good shape.  When the system was installed, all of the joints were sealed with duct mastic and then insulated.

The only issues I found were where the ductwork joined the heatpump itself.   Tape is an evil thing when exposed to attic temperatures for many years as it starts to gets brittle and either loses it's grip or tears easily.  The only option is to take out what's bad and replace it.

Since my ductwork was already sealed and insulated I'm not going to get a huge savings from the work I did today.  On the other hand, it only took about an hour to check it all out and I used maybe $0.50 worth of aluminum duct tape that was left over from a roll used on the solar air heater.

There are several sources (here and here) that suggest that 10% - 30% of the conditioned air in a typical home is lost via leaks in ductwork.  It's an easy and cheap thing to fix...

Water Heater Analysis - Part 2

After some discussions with Gary over at BuildItSolar I've decided that the hot water heater was coming on much more often than it should for its warming cycles when the desuperheater was turned off for the winter.  Over the past month it has averaged coming on for 5-6 minutes about every 90 minutes.   This results in about 90 minutes of "on" time per day just to keep the tank warm.  The graph below shows the warming cycles of a typical day.

90 minutes a day @ 5500 watts = 8.25kwh per day = $.90/day.  Since I keep the desuperheater off from Nov-March, that's about $140 per year in tank warming cycles.  The question is why is it coming on so often.  Gary suggested that I might have a thermosyphon loop occurring and after some investigation I believe he is correct.  The downstairs heatpump sits right next to the water heater and the plumbing between the two units looks like this:

When the valve on the cold water line at the top of the water heater is open (as it has to be when the desuperheater is on), there is an instant flow of hot water out of the top of the water heater, down through the heat pump and back into the base of the water heater.  Shutting the valve stops the flow and the lines stay cool.  Even though all the piping is insulated, shutting the valve had an immediate affect on the number of tank warming cycles that occur during the day as shown below.

The tank now cycles on for 7 minutes every 6 hours.  The "on" time for warming cycles has been reduced from 90 minutes to 30 minutes a day.  For my 5500 watt water heater, that's 825 kwh per winter that I'm not using and 982 pounds of CO2 that's not being pumped into the air.  In addition I'm also saving $.60 per day or $90 a year.

Water Heater Analysis

Since I've been able to work around the load profile problems with the TED 5000, I've started collecting enough data that I can start to change some things and see what affect it has on my hot water heater. 

This is a typical load profile for my hot water heater for a single day.  The heater was on for about 125 minutes of which 34 minutes was due to the shower at 8am.  The other 90 minutes of run time during the day was mostly just the tank keeping the hot water that I'm not using... hot.

I then turned on the desuperheater for the heat pump.  I usually keep this turned off during the winter and really had no way in the past of telling how much heat it supplied to the hot water tank.  Tank run time for this day was 68 minutes for the two showers.  Note that at no time during the day did the hot water heater come on to keep the tank warm.

Is this good?  I'm not sure.  During the summer months the desuperheater is always on as any heat that I can pull off the coil and put in the hot water tank is heat that doesn't get pumped out to the ground loops.  But during the winter, any heat that I pull off the coil and put in the tank is heat that's not going into the house.  So either the hot water tank comes on more often, or the heat pump runs longer.  I'm not sure which option is better.

Some of the issues/thoughts with using the desuperheater during the winter that I see are:

1. If the desuperheater is off, the hot water heater will only come on when the temperature in the tank drops below a certain level and the water actually needs to be heated.
2. If the desuperheater is on and it's a nice day outside such that the heat pump doesn't come on, it's the same as having the desuperheater off and the hot water heater supplies all of the hot water.
3. If the desuperheater is on and it's cold outside, whenever the heat pump comes on, heat is pulled off of the coil and pumped into the tank even if it doesn't need it.

This last thought is the one that I have the most trouble with as it seems that I'm wasting money.

HP PSC 2510

While I was surveying the house with a Fluke thermal imaging camera the other day I happened to take a look at my HP PSC 2510 all-in-one printer/fax thingy.

I sure wasn't expecting it to be using electricity as I usually keep it turned off since it's really only used maybe once a month.  When this picture was taken the printer had been off for over a week.  Interested in how much energy it was actually using, I plugged it into a Kill-A-Watt meter.

• On (idle) - 18 watts
• Off (or so I thought) - 10 watts

So, 10 watts for an entire year equals 87.6 kwh, or about $10 a year to sit there... off.   For the thousands of these that sit around "on" all day/night, it's about 157 kwh/year ($17). 

My Half Project - Thermal Imaging

The other day I undertook an effort to scan the entire house with a Fluke Ti32 thermal imaging camera.  The good news... no bad news.  I didn't find any major issues.  I had hoped to run these scans when there was a large difference between inside/outside temps so that any issues would be more apparent, but the day I could get the camera the outside temperature was about 15 degress below the inside temp.  I have arranged to get the camera again during the summer.

The Fluke software is really nice in that it allows for a lot of post processing of images.  I really like that you can overlay the thermal image on the visible light image so it's easy to see where the picture was taken.

This is the backdoor leading into the garage.   The bottom seal could use a little work.  It's very obvious where the cat plucks at the seal in the lower left corner.

I was surprised to see how the windows looked.  This is a window on the north side of the house at 10am.  Outside temp was around 50.  All of the heat loss appears to be right around the edge of the window.  All of the windows had this same look.

The insulation on the water heater appears to be good.  Tank temp is kept at 120 and most of the outside of the tank is around 68.  The base is around 80 and it appears that the connection between the tank and the geothermal heatpump could use a little more insulation.

Looking straight up at the roof ridge.  Can you guess which is the south facing roof?   Outside air temp was 50, attic temp was 55.

Next step is to fix the few minor issues that I found.

TED 5000 Load Profiling

The HA software has been logging "seconds" data from the TED for a couple of days and I've started to do a little bit of post processing on the data.  For the most part detecting when the hot water heater kicks on is easy.  Below is a snapshot of data that I'm pulling down from the TED and saving.  The log has date/time and usage in watts.

03/05/2011 14:34:21, 1362
03/05/2011 14:34:22, 1362 
03/05/2011 14:34:23, 1362  
03/05/2011 14:34:24, 6897  <-- DHW ON.    Load change of ~ 5500 watts
03/05/2011 14:34:25, 6897

This is easy to parse and detect that the water heater came on.  But it's not always this simple to detect.  Yesterday the water heater came on over a few seconds...

03/09/2011 00:49:59, 2796
03/09/2011 00:50:00, 2796
03/09/2011 00:50:01, 4109  <-- started
03/09/2011 00:50:02, 4109
03/09/2011 00:50:03, 4109
03/09/2011 00:50:04, 4109
03/09/2011 00:50:05, 4109
03/09/2011 00:50:06, 8104  <-- full load

And later in the day it came on while the heat pump decided to turn off.  This is a more difficult situation to detect as I have no data to indicate a load change of ~5000 watts.  Best I can do is detect the off event and back track and try to guess where the on event occurred.

03/09/2011 07:13:53, 2694
03/09/2011 07:13:54, 5697
03/09/2011 07:13:55, 5697
03/09/2011 07:13:56, 5697
03/09/2011 07:13:57, 5697
03/09/2011 07:13:58, 5697
03/09/2011 07:13:59, 6153  <-- DHW ON, heat pump is shutting off.

I can set up the HA software to detect most of these different "on" events because I know what's on each panel and I know that there isn't another load like the water heater on panel 2.   These multi-second on events is why I think that the load profile software within the TED has difficulties and sometimes misses either the on or off event.  The profile that it learned was for 5500 watts almost instantly and for most cases this is how the water heater comes on.   If the device doesn't come on like that every time, then the TED is going to have issues detecting it.

Detecting multistage loads while dealing with other loads going on/off will be challenging.

TED 5000 Load Profiling

I finally got the load profiling data for my hot water heater that I could not obtain directly from the TED.   I went through a couple of iterations of retrieving data from the TED before deciding on a workable method.  I tried retrieving the historical minute data but that didn't give the resolution that I wanted.  So I switched to retrieving the historical second data.  It's a lot of data and the TED is really slow at delivering the data via XML.  I found in the API where I can get the raw second data and this downloads much faster.  The TED gateway only stores about an hour of second data so I have my HA software downloading the second data every 30 minutes and saving it off to disk for later processing.  This will be a workable solution.

The graph above is from the first full day of pulling second data from the TED.  It was a very low usage day for DHW which is what I wanted so that I could get a feel for how often the water heater comes on and for how long.  Total run time for the hot water heater for 3/6/11 was 83.95 min @ 5500 watts for a total of 7.7 KWH.  Almost all of this is the heater coming on just to keep the tank hot.

My Half Project - Window Shades

34... I thought the answer was supposed to be 42, but 34 seems to be the number of shades that have been installed on the south facing windows.   The shades do not cover the transom windows so a lot of light will still be able to enter all of the downstairs rooms.  I also didn't install shades on windows that are mostly in the shade of the upstairs deck.   I'll start closing these when it gets warm enough for the AC to kick on.  I'm interested in what affect these will have on the hot summer months.

TED 5000 Load Profiling

The Load Profiling still isn't working like a want.  As I mentioned in a prior post, the TED is missing some of the on/off events for the water heater.  While waiting to do the firmware update last night, I saw on the graphing tab that the water heater turned off in two seperate events.  I'm guessing that both elements were on and turned off about 3 seconds apart.  This was enough for the TED to miss the profile event.  Ugh.  The current plan now is to change the load profiling code that I put in the HA software yesterday so that instead of pulling down load profile data that the TED has collected, I'm going to pull down the historical minute data and parse that to find the water heater events.

The advantage to this is that the HA software can have more intelligence built into it since I know what loads I'm looking for and can set it up to handle events that occur over a period of time.  I will lose some resolution by looking at the minute data instead of the seconds data, but I think that will be ok.  One other note about the minute data is that the TED seems to only keep about 48 hours worth.  I'll have to set the retrieval of this on a polling timer and save the parsed xml out to disk for later processing.

TED 5000 Load Profiling

I had some success and some failures with the TED 5000 today.  First the good news... I made the changes to my HA software to query the TED for the historical load profile data.  This works well as it's now set up to pull data every 4 hours and I can also force a query as well.  The xml data is parsed and written out to disk making sure that there are no duplicate entries.

Now for the bad.... Failure #1, after I parsed the historical load data from the TED I noticed that it didn't always detect the water heater turning off.  When the next "on" event happens it won't log that either since it thinks the heater is already on.  If the heater comes on for 5 min, goes off for an hour, then comes on for 5 min, I will occasionally get xml data returned that says that the device was on for 1 hour 10 min.  It doesn't happen frequently, maybe once or twice a day.

Failure #2, I upgraded the TED gateway firmware from 1.0.400 -> 1.0.406 and the Footprints from 1.0.222 -> 1.0.223.  Checked the load profile tab and it still says I have no data.  Which is odd since I can query the XML directly and get the data.

In other interesting news, it looks like the water heater cycles on/off enough times during the day to get between 1 hour 30 min & 1 hour 45 min of actual "on" time just keeping the tank warm in hopes that I will use some hot water.  This is a trend I saw earlier but I want some decent data on disk to back it up. 

There are two things I'd like to compare that data with.  First, I currently have the geothermal DHW preheat turned off for the winter months.  I've never gotten a clear answer from the hvac people regarding if it should be left on or not.  I'd like to see what affect turning it back on has if any.  Second, I'd like to see how often the water heater turns on when the geothermal is in AC mode and the DHW preheat is on.

TED 5000 Load Profiling

Good news for the TED 5000, I've found a way to work around the problem with the load profile tab not showing
any historical data.  Since the TED web site didn't want to easily give up their api, a few internet searches led to what I needed.  I can query the TED gateway directly with an http request and get an XML document returned that has all of the load profile historical data.  I like this method even better than just accessing the TED via IE as now I can retrieve the data and store it so that I can use it as I see fit.   I'll be adding the ability to retrieve this data to my HA software soon.

-<LOADPROFILE>

   <DEVICE>8</DEVICE>

   <DATE>03/01/2011 19:33:58</DATE>

   <RATE>9385</RATE>

   <STATUS>0</STATUS>

   <POWER>5252</POWER>

 </LOADPROFILE>

- <LOADPROFILE>

   <DEVICE>8</DEVICE>

    <DATE>03/01/2011 19:28:10</DATE>

    <RATE>9385</RATE>

    <STATUS>1</STATUS>

    <POWER>5252</POWER> 

 </LOADPROFILE>

My Half Project - Degree Days

As part of my effort to figure out where I'm at on energy usage and knowing that heating and cooling are a large part of my electric bill, I did some research to help understand what affect outside temperatures have on my electric bills.

In looking at the last three years worth of electric bills I was surprised to find out just how consistent my energy usage has been.  I had less than 5% difference in kwh's used across those three years.  Degree day calculations for those years is a little different story though with an almost 17% difference.  What I found interesting is that the degree days for 2010 were much higher than the previous two years but my energy usage for 2010 was lower. 

When I look at the monthly kwh usage a trend definitely emerges, I spend more to cool my house in the summer than I do to heat it in the winter.  However, when I look at the degree days that shouldn't be the case.

Obviously something else is going on here.   I believe that what's happening is solar heating of the house via the large expanse of south facing windows that have no blinds or shades.  The sun helping heat the house would lower the energy usage during the winter and would increase it during the summer.  Installing shades will be a project for this spring.