Just installed my first Nest learning thermostat.  Really easy and affordable.  Check it out and let me know what you think:

http://www.nest.com/

 

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The energy tracking feature seems to have serious promise.  Most people have no idea what their energy use is, and what you don't track you can't conserve.  For most people energy bills are so hard to read they are nearly useless for adjusting behavior or understanding savings opportunities.  

 

Anything that get's us closer "to the pump" is great in my book.  As far as controling HVAC equipment to "game" savings, I'm really dubious.  But they need to sell the thing, and selling to preconceptions works no matter if they have truth or not.  

 

Here's an article that does a nice job reviewing this device.

 

Technology of the 1970's may have meant setback could get efficient operation twice a day from grossly oversized equipment, but high efficiency equipment today does not operate at one output.  Also, insanely leaky houses meant reducing air temperature could offer significant savings, but tighter houses aren't losing heated air at obscene rates.  

 

Gaming operation of hvac equipment to save serious money is a broken assumption.  Again, if you don't do it one way, then do it another and MEASURE BOTH, claims of "savings" are absurd. 

It seems like you are saying that setting back the temperature when you sleep or are away does not save energy -- at least if what you mean by "gaming operation" is temperature setback.  I've performed multiple studies for utility companies based on actual before/after billing data that demonstrate energy savings from setback thermostats.  If you reduce the delta-T then you reduce heat loss/gain.  I agree with you that very efficient and/or high mass homes and some types of equipment (heat pumps, mod con boilers) may not benefit as much or at all from setback, but the vast majority of existing homes can certainly benefit.
I agree with you that very efficient and/or high mass homes and some types of equipment (heat pumps, mod con boilers) may not benefit as much or at all from setback

 

Hi Michael,

 

People tell me all the money they save.  I ask how much and they say "a lot".  

 

I can't do anything with "we've saved a lot".   What is "a lot?"   Do you put "a lot" on the amount line when you make deposits at the bank?  "Vast Majority" is like "a lot".   No bank will accept that deposit slip.

 

In the 70's we had a very different world.  This prescription fit "the vast majority" then a lot better than it does now, and the diagnoses and cure was not broadly understood or available.  Today there are diagnostics available to determine causality, and prescriptions that are likely to cause more harm than good are clearly malpractice.

 

The bigger problem with blanket legacy strategies is the behaviors they create cause not only distorted assumptions about how homes perform, they are an impediment to true efficiency improvements.  

 

A homeowner who "thinks" they are saving boatloads of money by implementing an 8f setback strategy becomes an unhappy homeowner when I replace their grossly over sized equipment and install properly sized equipment because their legacy behavior causes my design to fail.  Recovery no longer takes 15 minutes, it takes an hour.  

 

The typical HVAC guy doesn't want that no-pay complaint phone call.  The energy bill, and therefore energy savings, are not their problem.  The phone call is.  Do you see how setback advice perpetuates this major problem?

 

Furthermore, your delta arguments and studies seem to jump to conclusions about causality.  I think they don't prove casualty.  I think they miss significant interacting factors.  

 

Over sized legacy equipment short cycles. (If you drive a hummer 100 miles a day, will you use more gas if they are all city or if 80 of those miles are highway?)  Setback with legacy equipment allows equipment to get to the highway and operate efficiently twice a day.  Long hard runs, long shutoffs.  Not very effective for delivering comfort.  That is the exact opposite of how modulating equipment achieves efficiency, which load matches.  

 

but the vast majority of existing homes can certainly benefit.

 

People tell me all the money they save.  I ask if they track and they say no.  I can't do anything with "we've saved a lot".   What is "a lot?"   Do you put "a lot" on the amount line when you make deposits at the bank?  "Vast Majority" is like "a lot".   No bank will accept that deposit slip.

 

I think the homes that benefit from this outdated strategy are homes we would consider broken.  They are leaky homes with crappy equipment.  Fix them.  Instead of telling people how to treat their energy hog symptoms by gaming slight and unmeasured savings, at significant cost to comfort and a stuck legacy mindset that perpetuates thinking that conservation means discomfort, teach them they can fix the problem. 

 

Prescription without diagnoses when tools for diagnoses are readily know is major malpractice.  There is a cure.  Fix crappy homes. Setback is a placebo. 

 

 

 

 

It seems like you have some sort of aversion (hostility?) to controlling temperatures in homes yet some sort of faith-based belief in the benefits of right-sizing and multi-stage equipment.  I've got some data on thousands of homes (and physics) that suggest reducing temperatures in the winter when people aren't home or are sleeping can save a good amount of energy in many homes.  It is not a legacy mindset but simply the real world we live in-- most homes can't be retrofitted to the point where setback won't work -- unless you're into $100k deep energy retrofits. 

By the way, I'd love to see any data you have showing energy savings from right sizing equipment or using multistage equipment (compared to somewhat oversized single stage equipment) -- seriously, I would.  The latest data I've seen have not supported your beliefs very well.

Hi Michael,

 

I simply wanted to know if the TREAT savings being promised my clients had any level of accuracy.  If I'm going to be involved in a scheme that tells people they will save $500 a year, it better deliver or my total cost analysis is less than toilet-paper.  

 

My studies are self funded, they are not backed by a government paycheck over 1000's of homes, so they have little statistical significance.  Conclusions were anicdotal to my primary goal of having confidence in my modeling software.  But these conclusions don't jump to simplistic assumptions either.  All I'm suggesting is the simplistic assumptions of causality from setback savings be considered.

 

I save many of my customers 30-70% on their energy bills.  A big part of those savings is from downsizing equipment.  I work in a field where consumers make the decisions, not WAP.  People in WAP don't seem to understand what a different world it is when the government isn't writing the check for the improvements.  This is not prescriptive work with a steady paycheck at the end, it's much harder and more complex than that:

 

I'll try to address your comments one at a time:

 

Controlling temperatures in homes is great.  Helping dispell ignorance about how combustion appliances operate, even better.  Let's start with you.  

It seems like you have some sort of aversion (hostility?) to controlling temperatures in homes yet some sort of faith-based belief in the benefits of right-sizing and multi-stage equipment.

 

 

Because setback saves energy in a tested home does not mean that energy is saved because of reduced delta losses through surfaces.  I assert this simplistic conclusion is seriously flawed.

 

Ancient cultures made human sacrifices in the hopes famine would abate.  When famine abated they concluded it was due to their sacrificing humans.  You may embrace this type of thinking, but it makes me uncomfortable. CORRELATION DOES NOT PROVE CAUSALITY.  I think a step is missing, jumping to the conclusion instead of exploring further.   If setback saves, WHY?  WHAT are the factors in play?  

 

I assert the savings is due to gaming oversized equipment into being right sized for 2 significant periods of btu delivery a day (also improved delivery efficiency on the duct work), and possibly reduced stack pressure losses on extremely leaky sample homes.  

 

Without understanding equipment size and envelope leakage, any conclusions about why setback saves are extremely flawed.  

 

It seems like you have some sort of aversion (hostility?) to controlling temperatures in homes yet some sort of faith-based belief in the benefits of right-sizing and multi-stage equipment.

 

Clearly you don't believe over-sizing equipment has a huge energy penalty, or that right sizing is a huge opportunity.  I don't have room here to help you understand all the interactive aspects here, but if you talk to any of the recognized experts they will set you straight.  

 

In summary, furnaces upon start-up are horribly inefficient.  Any doubts, let your CO detector prove it to you.   The whole mindset that it's better to have equipment run for as short a period as possible needs to be removed from the public mindset wherever it exists.  We are belching huge amounts of useful energy out flues because equipment short cycles.  

 

It is not a legacy mindset but simply the real world we live in-- most homes can't be retrofitted to the point where setback won't work -- unless you're into $100k deep energy retrofits.

 

You just implied that shell retrofits are extraordinarily expensive and out of reach for most people.  Do you really want to perpetuate the myth that energy efficiency retrofits are extraordinarily expensive and financially unrewarding for the homeowner?  

 

Reorienting people at equipment replacement to consider adding envelope measures is hard enough without help like yours!!  I find it very disappointing that someone claiming to be an energy professional would make such discouraging statements.  In most leaky homes $2000 worth of air sealing is the single best investment a homeowner can make.  Much much better return than $250 on a thermostat.   

 

By the way, I'd love to see any data you have showing energy savings from right sizing equipment or using multistage equipment (compared to somewhat oversized single stage equipment) -- seriously, I would.  The latest data I've seen have not supported your beliefs very well.

 

Most of my projects have envelope measures, but I have one job that I was unsuccessful in selling the envelope work.  We went from 2 stage draft induced to 5 stage hybrid with a drop of 20,000 on the high output.  The annual total consumption went down 29%.  Again, only anecdotal (getting use a year later is cumbersome and at my own expense). 

I've got some data on thousands of homes (and physics) that suggest reducing temperatures in the winter when people aren't home or are sleeping can save a good amount of energy in many homes.  It is not a legacy mindset but simply the real world we live in--

 

You may have all kinds of data, but are you looking into it deeply or simply looking at the face of it and drawing simplistic conclusions?  Do you have blower door numbers and load calculations?  Are you looking at equipment sizing?  Are you looking at per sf btu consumption?  

 

Claims of "I've got physics" without any real analytic's takes me back to my "saves a lot" argument:

I can't do anything with "we've saved a lot".   What is "a lot?"   Do you put "a lot" on the amount line when you make deposits at the bank?  "Vast Majority" is like "a lot".   No bank will accept that deposit slip.

 

Setback strategy is an impediment to downsizing.  Setback is in the way of HVAC contractors who would like to sell smaller equipment.  

 

Setback was a useful energy savings tactic in the 1970's just like Selectric typewriter were amazing time savings devices for typing letters.  Technology and better building science knowledge has made both obsolete.  People proposing setback as an effective energy saving tool are selling snake oil treatments to a problem that is easily and cost effectively cured.  Furthermore, the behavior creates false assumptions within the general consciousness that is an impediment to good building science solutions. 

 

Stop treating symptoms for diseases that are easily cured. 

 

If you check out the more recent research (e.g., from FSEC and ECW) on AC sizing and read the recent Proctor article in Home Energy you will see that there isn't much energy penalty even for oversizing cooling systems.  Your claims about heating system efficiency impact of oversizing are also at odds with more recent research.  Cycling losses for modern equipment are considerably lower than older equipment and so oversizing penalties are much smaller.

I suggest you Google my name to see what sort of work I've done before jumping to insulting conclusions. 

You're not wrong on this, but the reality is that the vast majority of homes still are rather leaky.  Even homes built a few years ago are typically leaky, have poorly installed systems and are worthy of retrofit.  

It's a nice device, I'll be surprised if it takes off in any meaningful way as it's price point seems too high to me to get mass market traction.  Begs the question $250 Tstat vs Energy Audit  I'd wager with minimal direct installs, Auditors could beat the pants off the Tstat!

Ted, by saying that homes that benefit from setback are somehow broken, you're making a huge generalization, and one that flies in the face of physics and common sense.

You wrote:
I ask how much and they say "a lot". I can't do anything with "we've saved a lot".

Irrelevant! Do you really think homeowners can answer that question for any other energy efficiency improvement in your arsenal? Come on! What kind of lame argument is that?!

Your main issue seems to be with potential callbacks. In my experience, slow recovery is only an issue with heat pumps (to avoid use of electric supplemental heat), and even then, it can be managed (fodder for another discussion). Moreover, even a perfectly sized system will recover quickly on all but the hottest and coldest days. And since you're such a strong advocate of variable capacity equipment, I'm sure you realize in that case there's little if any downside to moderate oversizing, which assures recovery will nearly always be fast. Even with fixed capacity equipment, 25% oversizing isn't an issue except perhaps in extreme humid climates. Egregious oversizing is indeed a bad thing, but you needn't to go there to achieve quick recovery at design conditions.

In making your argument, you invoke some truths regarding thermal mass (furniture, etc.) and misuse of setback. However, thermal mass is only an issue with deep setback. In making your argument, you use the example of 8F. I think most of us would agree 8F is too much, except for perhaps a long trip. You also point out how some modeling software might overstate the benefits of setback. I suggest you take that up with the software developer, rather than using that to prop up your long-standing advocacy against the use of setback.

As for misuse of setback, homeowner education is clearly essential to achieving big energy savings. I've made this a cornerstone of my design process. The homeowner needs to understand what they can expect from their system, just as we must consider their expectations in our designs. Everyone is different, and indeed I have some clients for whom I have advised against a programmable stat. I find this interaction to be the most rewarding part of my work. Sound like you prefer not to have that conversation.

One more thing. Your one-size-fits-all rejection of using setback in high performance homes completely ignores the fact that some folks simply aren't comfortable if they keep the same setting 24/7. When working with homeowners, I have them describe their temperature preferences. Most say they prefer a cooler bedroom at night during winter, and a fair number prefer a cooler bedroom in summer as well. Personally, I set my AC at 77 during the day (I work at home and find that to be quite comfortable) but I need my bedroom to be 73 at night (plus a ceiling fan), otherwise I have trouble sleeping (I'll admit, I've become spoiled that way). In the winter, I prefer 69 during the day and 65 at night. I guess you would have me be uncomfortable for much of the time?

Wow this looks like a sleek and cool device.

 

 



CLEVER & Very Cool Too! 
In the past, programming thermostats could turn out to be challenging.  I wonder if the minions who are now fairly
proficient with and masters of their smart phones will really like this device.  Many who previously had been challenged by programmable thermostats like myself and our now the masters of their smart phones may really gravitate to the Nest.   The Nest may be a very good way to empower allot of people to get back in or more in the game and take smarter control of their heating and cooling.  Increasing their interest in energy efficiency with a product like the Nest could be the initial step onto the path of energy efficiency for some.  This would surely be a win, even if it’s partially because of their tech side, and the need to be the master of their all powerful smart phone.  The Nest is cool.  I know I want to own one.

review of Nest @ new york times:

http://nyti.ms/sX66eZ

Interesting.  

 

...discourage people from setting their thermostats to 90 degrees, for example, thinking that the temperature will rise to 70 faster.

 

Clearly a device that prevent's idiot behavior can save.   No argument here (automatically locks on windows at temps below 65 could probably save a fortune also).  

 

And the fact that it may have some TRACKING features is FANTASTIC!  

 

But some of this sounds like candidacy for Phil's Bull$*** Performance Index thread:

 

$250 is a lot to pay for a thermostat. But Nest says that you’ll recoup that through energy savings in less than two years.

 

Nest says that turning down your thermostat by even a single degree can save you 5 percent in energy.

 

So you guys buying this thing, please take a snapshot of your meter and report your prior year energy consumption upon install.   Then  a year from now report the "test out" number so we can actually bring some REALITY and SAVINGS MEASUREMENT to this "you'll save the moon" industry.  

 

 

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