Smart Thermostat: The Nest

"When they are used, programmable thermostats can significantly cut energy, on the order of 20 percent to 30 percent."

I would love to see their math on that one...

Since heat loss goes as the temperature difference, in order to save 30%, the average temperature difference needs to be 30% lower. For me, that would be (68 - 24) * .3 = 12 Which means an average temperature of 55. It takes my house about 2 days to even get down to 55 with no heat. Assuming equal time, the low would then be 42. Meanwhile what happens to all the moisture when the house gets down to 42? It condenses somewhere, where it begins to rot your house.

My experience has setbacks saving up to about 5%. And that, in the worst houses.

Spend the $250 on some type of insulation, or air sealing instead.

 

There are a number of other web programmable t-stats out there. We use one on a weekly rental house to pre warm before guests, and to turn off the heat when we know they are gone. We also are getting a entry lock that we can control though the net.

Icarus

 

I have a smart thermostat from my utility. They can turn down my air conditioning if there are problems on the grid. Highest demand is 3-7 pm in the summer. I care the most about airconditioning at night, so I have it get cooler at 8pm and over cool at night, letting it warm up during the day. No web control, but I don't really need it. If I get home early and I'm hot, I can just turn it up.

 

We have 'remote' for our HVAC ... but it's not web enabled ... rather it's like a mini TV remote. 3 buttons ... up, down, return to default. Each up or down clicks it one degree colder or warmer. beep ... beep. We have 2 remotes. From opposite ends of the house, we too play the game of tempemperature warfare. beep beep . . . . BEEP BEEP BEEP!!!


.

 

Funny. Too much human energy to walk to the thermostat. In grad school, I had temperature warfare with one of my roommates, even after I offered to pay more of the bill. He wanted it set to 82, I wanted 78, I was much more of a weather wimp.

Hill, I assume your wife typically wins this warfare. I know my gf is actually in control.

 

Yes, its was part of an austin energy efficiency program.

 

Yep. When it comes to "being right" ... or "being happy" ... I chose being happy.
But the temperature warfare typically starts during night time. Neither of us wants to to crawl out of bed to go downstairs to change the setting. It'd be nice to have dual HVAC/upstairs/downstairs but that's out of our money range.

So - is that the 'real' austin'? or just the city? .

.

 

Austin Energy is the municipal utility for the city of austin. The city council controls it, and every now and then we vote on whether to keep it public or privatize it.

 

Why in the world would anyone (with a lick of sense) want to privatiize it?

An interesting example, Thunder Bay Ontrario runs one of the oldest and most successful municipal telephone companies. They offer competitive rates for all services from simple land lines, to ISP service, wireless and wireless Internet service. They serve a very wide (huge,, thousands of sq miles) of remote wireless networks serving very sparse population, all at a price competive with the national carriers.

I use a wireless rocket hub for phone and ISP since I am very remote. It cost me $50 per month for unlimited phone and up to 10 gigs of data, $75 for 20 gigs.

The upshot is that the company throws off tens of millions of dollars of profit back to the city coffers every year, this in a city of 100,000. (~$15 million in 2010)There have been moves over the years to privatize the service by special interests, but the service is great, the price is competitive, and the net profits stay in the community. By being municipal owned, they can afford to serve marginal areas (like mine) that serve a greater public good. The big guys wouldnt bother, as there is little or no profit in it, even if they are making buckets of money on the mass.

Same hold true for most municipal power companies/co-ops IMHO.

Icarus

 

Hey Icarus,

This is in a polical capital city in a political state, hence there is lots of politics involved with this municipal utility. Unlike your example, Austin Energy does not make a profit, and should not make a profit, a profit would be an energy tax on its users.

The problem with it being a municipally run utility is there is political patronage and inefficiency. There are employees that are there just to advocate for electric cars or to help people figure out how to make their homes more energy efficient, or decide which solar panels and provide low interest loans to put them in. The mayor during his campaign even promised to get the coal plant closed earlier. The politics are actually responsible for a lot of the ways electricity is changing in the state. If you are like me that actually want more renewables and less pollution you like the politics and don't care if it makes rates slightly higher. If your politics run with the governor or TCEQ then you might want to make it private. For those people I'm one of the bad guys. The amount of renewables added have actually made austin energy's rates slightly lower than the state average. If Rick Perry ran austin energy, I would vote to privatize it.

 

Unless you need the remote programming feature, or need to customize the heating/cooling schedule day by day, this probably offers little additional savings beyond a standard 4-setting/7 day programmable thermostat.

You need to be willing to set the temperature back considerably for this to offer significant savings. Once you've done that, that's about it for savings.

The EPA says $180 savings on a $2200 annual bill from a regular programmable thermostat is possible. They don't even claim that's typical. Same page calls for an 8 degree or more nighttime setback. So the "30 percent savings" claims seem unlikely.

Programmable Thermostats : ENERGY STAR

OK, these guys claim (up to) 30% AC savings from running the fan continuously, in a dry climate. Seems far-fetched to me, but Virginia in summer is not a dry climate. If you have humid summers, then that's likely not going to work for you either.

There's a major caveat if you have a heat pump. Either don't do this or invest in a programmable thermostat that is designed for use with a heat pump. The issue is that a standard thermostat will call for secondary heating (typically electrical resistance heat) if the temps fall below the set point for (e.g.) 20 minutes. Which means that if you use a standard programmable thermostat with a heat pump, and you have a deep nighttime setback, you'll end up triggering your resistance heat every morning. Smarter thermostats know that you're below the setpoint because you're "waking up" from the setback, and won't call for resistance heat (or will call for it after a much longer time).

Anyway, there's no magic here. Just physics. Reducing the average temperature of the house (in winter) reduces energy required to heat it. Raising it in summer, ditto. Except for the caveat about heat pump systems, that's it. A programmable thermostat just does that in a way that minimizes the impact on your comfort.

 

You are extremely lucky (smart) then. In Maine, there are 4 houses I would make that claim for (out of 270,000 or so). Most houses I audit could save over 50% of their heating budget by insulation and air sealing (with quick paybacks (<7 years)).

If anyone wants to pay $250 for an "entertainment thermostat", be my guest.