Wattvision’s Blog

Wattvision has taken pride in making energy sensors and software that 'just work' since 2009.  Today we're excited to announce our commitment to the Green Button Initiative, an industry-wide effort to unite energy data around clear, concise standards -- initiated in response to a White House call-to-action.  Wattvision is unique among adopters of the green button standard, as our sensors and software can both produce and consume Green Button Data, empowering consumers and businesses to take control of their energy use.

Over the last three years, we've made our data accessible to 3rd party developers of hardware and software, using our own API.  Hardware developers can push data to our site using our upload API and software developers can download data produced by wattvision's sensors using our download API.  We are keen to offer upload and download of Green Button data, making Wattvision an even more seamless solution for a wide array of energy management and energy tracking challenges.

We are excited to be part of a rapidly growing industry where energy consumers are starting to unlock increasing savings through energy awareness and management.  Our adoption of the Green Button Standard only serves to accelerate this growth.

This is the fifth in a series of guest posts by Ted Borer, PE, the energy plant manager for Princeton University. He is actively involved in campus and community energy efficiency and carbon emissions reduction efforts. He has over 25 years of experience in the energy industry, is a registered professional engineer, and holds both undergraduate and graduate degrees in Mechanical Engineering as well as the CEM, CEP, and LEED^AP Certifications. He has published numerous magazine articles, technical papers, and a book chapter on topics relating to energy and cogeneration. 

The Wattvision offers us a means to study our electric use in highly granular detail. By looking closely at the data and considering what is happening in the house, we can determine both the magnitude and duration of electric use for a specific activity. Then we can easily calculate the cost and decide whether that cost is good value.

What follows is a close technical analysis of my energy use.  Wattvision may automate these sorts of analyses, but until that time nothing beats looking at the data.

For example, the graph below shows a recent day where we ran the clothes dryer starting at about 12:15 PM.

Let’s look at that time period in detail by selecting a range between 12:00 and 2:00 PM.

Looking at the detail above, or referring to a .csv (comma separated values) file downloaded from wattvision, it’s easy to see that the dryer ran from 12:13 PM until 1:20 PM. Before it began, there was a base-load electric use of 1700 watts in the house. We can imagine the drum motor running continuously and a resistance heating coil turning on and off based on a temperature and humidity signal. The drum motor may only use a hundred watts or so, but the resistance heating coil looks it draws about 5000 Watts when it’s on! Since it cycles on and off, the average household demand during the operating period is about 5500 Watts. 

With that information we can determine the energy consumption and cost of drying a load of clothes:

5500 Watts while the dryer operates

-1700 Watts base-load activity

3800 Watts, average clothes dryer use rate 

From 12:13 until 1:20 is 67 minutes or 1.117 hours

(3800 watts) x (1.117 hours) / (1000 watts per kilowatt) = 4.2446 kilowatt-hours

If our power costs $0.20/kilowatt-hour, then drying that load of clothes cost:

$.20 x 4.2446 = $0.85 

If we dry one load of clothes per day for a year, then our annual clothes drying expense is:

$0.85 x 365 days = $310 

…and we’ve used: 

4.2446 kilowatt-hours x 365 days = 1549 kilowatt-hours

Now we can consider whether using an electric dryer is worth the convenience, cost, and environmental impact or if we’d be willing to save $310 per year and reduce our carbon footprint by hanging our clothes on a line outdoors. Even if we paid $150 for a fancy “sun and wind powered” outdoor clothes dryer, it would have less than a six month payback! So we can easily justify it even if it’s only used in the summer. 

This is the fourth in a series of guest posts by Ted Borer, PE, the energy plant manager for Princeton University. He is actively involved in campus and community energy efficiency and carbon emissions reduction efforts. He has over 25 years of experience in the energy industry, is a registered professional engineer, and holds both undergraduate and graduate degrees in Mechanical Engineering as well as the CEM, CEP, and LEED^AP Certifications. He has published numerous magazine articles, technical papers, and a book chapter on topics relating to energy and cogeneration. 

We are all familiar with the concept of collateral damage, i.e., when one system fails, something downstream is also damaged. When a nail punctures your tire, the tire goes flat, but you’re also forced to drive slowly and are late to get somewhere, then if you drive on the rim to get home, both tire and rim need repairs.

I’d like to suggest that the reverse is also true, and our efforts to save energy will often yield delightful and unanticipated “collateral benefits.”  Here are a few examples:

We replaced an old oil-fired furnace with a new electric heat pump. The upgrade was justified on life-cycle savings alone. I.e., the cost of new equipment (less rebates and incentives) plus the cost of several years of operation was actually less than the cost of operating the old, dirty, inefficient equipment for several more years. Saving money was just the anticipated benefit. We also knew that by using a highly-efficient heat pump instead of burning home heating oil we would substantially reduce our family carbon footprint. But what we hadn’t anticipated were a few other nice benefits:

• We eliminated the liability of having 270 gallons of diesel fuel stored in our basement. 
• By replacing a combustion process with electric equipment we were able to move the air handler from the middle to the corner of the basement, allowing more recreational space.
• By eliminating the oil tank, we freed-up even more recreational space.
• We eliminated fuel oil deliveries.
• We moved ourselves farther from foreign fuel.

In another project, we did air sealing and added extra insulation in the house. We measured the “infiltration” (air leaks through all the tiny cracks and gaps in the house) before and after this work and anticipated about 19% reduction in energy use. In fact, that turned out to be a very accurate prediction of our energy savings. What we hadn’t anticipated was that the house would be quieter and more comfortable. With less leakage, the heating and cooling equipment didn’t have to run as often. With less leakage, the house was less drafty and more comfortable.  With less warm air exhausted through leaks, less cool air was pulled in through the basement. This resulted in such a dramatic decrease in measured radon levels that we were able to shut off the 100 watt radon exhaust fan – further reducing our energy use continuously all year!  (100 watts) x ($0.18/kilowatt-hour) x (1 kilowatt-hour/1000 watt-hours) x (8760 hours per year) = $157.68 savings per year! A nice added benefit!

Just a slight caution: think before you act. It is possible to make energy-saving changes that aren’t entirely satisfactory. For instance, do consider all the qualities you’d like in a new light bulb. That energy efficient LED light may be ideal. But think first about whether it’s got the right shape for your fixture and the right light color, and can dim if you want it to. Does it make noise? Will you use it enough hours to justify the cost? 

But go ahead and dive in! Start making thoughtful energy-saving changes. Think. Plan. Act. Then, expect to be delighted with unanticipated collateral benefits from your work!

We at Wattvision continue to work hard and our goal remains the same -- being the best end-to-end, hardware and software solution for consumers and businesses seeking to save money on energy.  So the big question is, what do Wattvision users "lose" when Google PowerMeter shuts down? Fortunately, nothing.  To simplify this post, we've broken it down by audience:

For Current Wattvision Users:

In a few clicks, you can stop sending your wattvision data to PowerMeter anytime before the official shutdown date, from your user account page. We will start doing this automatically as the date approaches.

For Users Interested in Energy Monitoring:

Since we've been shipping hardware and software since 2009 -- we already have a site where users can view, analyze, and compare data with other users. That's our site, wattvision.com, viewable on the web or on your mobile device.

Wattvision also has a few extra features like email alerts, charts updated every 10 seconds, and a live API, for example.  Many users have commented that they like our site better than PowerMeter's. Great! But the PowerMeter interface had a few neat features like comparisons with previous data. They're on our to-do list, and we'll continue to add features based on your feedback.

For Developers of Hardware and Software in the Energy Monitoring Space:

Like PowerMeter, we don't want to lock up your data.  You can download your data to your computer for analysis, or use our beta developer API for upload from your sensors or download to your apps.  We also hope other hardware and software developers will recognize wattvision as a reliable platform -- a platform that enables them to build products that help users manage energy consumption and save money on energy.

We first heard of Google PowerMeter about one month into our YCombinator funding round in January 2009.  You can still read their original announcement post.  Needless to say, we were scared.  A few of our closest advisors and friends said, "Google's in your space, you might as well give up now.  But hey, at least it validates your idea."  Thanks to our YCombinator connections we did get to meet with the PowerMeter team and work on compatibility betwen our products. It was a pleasure to work with them and it's a shame to see the product go.

The attention that the Google brand brought to our space was quite a boon for us, as well.  Without Google, we'll continue to work hard, make our customers happy, and generate our own excitement. On that note, just for this weekend we've announced a coupon (ends Monday 12:01a) $50 off, coupon code "byepowermeter".

Hi, I'm Diego, a Software Engineer at Wattvision.

We have recently added a highly requested feature to the site, a monthly view of your historical data. To help you get more out of Wattvision we're actively working on a series of features that our users will appreciate. Here's how to get to the monthly view:

Simply go to your house's "My House" page, and then click on the "History" tab. You'll see two options, one for a daily look at data, the other for a month long view.

What can you do with it? Here are some ideas:

• Can you spot seasonal trends? Has your A/C started running recently? Is it inreasing your monthly bill substantially?
• Conversely, do any consecutive months, or months of the same season, differ substantially? Why?
• Did you change appliances recently? Can you find the date you changed them? Are you saving money?

We are working hard to give you easier access to your information, and this is a small step in that direction. We love ideas, do keep sending them our way. If there's any feature or improvement you'd like to see please let us know.

-Diego

(can you tell when the A/C kicked in for the summer?)

This is the third in a series of guest posts by Ted Borer, PE, the energy plant manager for Princeton University. He is actively involved in campus and community energy efficiency and carbon emissions reduction efforts. He has over 25 years of experience in the energy industry, is a registered professional engineer, and holds both undergraduate and graduate degrees in Mechanical Engineering as well as the CEM, CEP, and LEED^AP Certifications. He has published numerous magazine articles, technical papers, and a book chapter on topics relating to energy and cogeneration. 

The Wattvision system offers a highly-detailed look at our energy use. It can measure the magnitude and duration of events that last for less than a minute and demand only a few watts, yet the data can be collected over a period of days, months, or even years. This level of detail offers us insight that we could never get by reviewing a monthly electric bill, or even by seeing an hourly total of power use. By carefully observing the patterns and durations of events in our energy use, and superimposing what we know about what is happening at the time, we can determine which activities use the most and least energy and which we may want to modify.  

Let’s break this down into manageable steps.

First it is helpful to develop a simple inventory of the things that use energy around the house. This may be informative when interpreting the Wattvision graphs and data.

We don’t need to be rigorously thorough or gather complete information about every light bulb. We just need to list the energy consumers that either use a lot of energy, or use energy for a long time. If you need ideas about what to look for around your home, the US Department of Energy offers a list of typical appliances and the energy they consume. This gives us a sense of what are large and small energy consumers, but it is important to check your specific equipment since there are great variations in efficiency and personal use.

Once we know what consumes energy, we’ll make a log of energy events for a while.

Then, we can combine this information with the Wattvision graphs and data to determine which activities used an important amount of energy, and which activities used less. The patterns, magnitude, and durations of events we see in the graphs will give us important clues as to what is happening. 

After making the log entries shown above, this graph was created by downloading that morning’s data from the Wattvision history page, opening it with an Excel spreadsheet, and adding notes.

Now we can begin to make a few observations about this snapshot of our energy use:

1. The biggest energy user is a steady demand of over 3500 watts. It was 20°F outdoors that morning. No doubt  most of this demand is from our electric heat pump that provides a large portion of our heating energy. If this ran at the same rate all day, it would cost: (3500 watts) x (24 hours) x ($0.19/kilowatt-hour) = $15.96/day!
2. There are random periodic spikes of over 500 watts. They are too many watts and too brief to be lighting. They may be associated with the well pump coming on to restore water pressure after toilet and sink use.
3. The coffee maker uses about 1000 watts for about five minutes. What does that cost? ($0.19/kilowatt-hour) x (5 minutes) x (1 hour/60 minutes) =  $0.0158, i.e., less than two cents. So the coffee and cream cost more than the electricity to make a latte’.
4. Cooking on the stove top or in the toaster oven both appear to use about 1900 watts apiece for several minutes.
5. There are two similar-looking steep downward spikes in energy use of over 1000 watts for about 5 minutes each. They are about 90 minutes apart. After the drop, energy demand increases again gradually over several minutes, not all at once. No specific energy event was noted in the log, so these may be associated with something that runs automatically. They are large enough that they probably relate to the heat pump. They may be associated with the heat pump defrost cycle. This is worth further investigation. Two sources of information would be the equipment nameplate and the owner’s manual.

We’ve made guesses about some of the events in the graph above. But repeated log entries and graph observations will allow us to confirm or correct these. The important thing is to begin by making observations to sort out what is happening. Then we can see what may be worth adjusting and what may not be worth the effort, inconvenience, or expense. What do we have control over? What are we interested in changing? Appliances that use a lot of power for a long time will have the biggest impact. If we have limited time and resources, the graph above suggests we’re better off looking for ways to reduce energy used by our heat-pump than by getting a more efficient toaster, stove, or coffee maker.

If you have an iPhone or Android phone, wattvision looks great as a web app. Just pop open your browser and visit http://www.wattvision.com.  You'll automatically get redirected to our mobile site, which is useful for walking around your house, turning things on and off, and observing the effects on your whole home's energy use. You can add the page to your home screen, as well.

The wattvision gateway, pictured below, is an 802.11B device.  It connects to your home's network and uploads the energy use data it gathers from the wattvision sensor attached to your meter.

Some of our customers have qualms about the speed of our gateway.  Won't a wireless-B device on my G or N wireless network slow down traffic for everyone? The short answer: no, it won't.

This paper, published by Microchip last year, is a study of network performance in a mixed networks and reaches this conclusion.  Can you cite a study that proves otherwise? Let us know!

We were just looking over some quotes from early press about wattvision. Here are three from EnergyCircle, TechCrunch, and Scott Adam's Blog (yes, the Dilbert Creator).  We're really honored to get feedback like this!  We were also excited by the reviews on the energy circle product page.  We strive for 5 star reviews and happy customers!