Monday, December 10, 2012

Video: Cold Climate Direct SDHW system with Recirculation Freeze Protection

I've mentioned this system before, and I finally made a video.  Please remember this is the first prototype system, and is intended to be temporary.  (It's ugly.)  Our current thinking is that the system isn't developed enough for general public consumption, but I definitely recommend it for do-it-yourself types in milder climates. It is literally the least expensive and most efficient system with freeze protection possible with off-the-shelf parts.

We've instrumented the prototype system, and are checking all the failure modes this winter and measuring the amount of heat lost due to freeze protection.  The video still raises many questions, so don't hesitate to ask them in the comments section here, or preferably at Youtube.

Smart Light Bulbs?

Phillips has recently introduced their HUE lighting system.   It's a wi-fi based light bulb control system for timing,  brightness and color.

How can you use it around the house to save energy?  Honestly, I can't think of any scenarios that would reap enough savings to justify a $60 bulb.

But in multifamily buildings, there's the hallway lighting to address.  In the middle of the night, the hallways could be dimly lit.  During the day, the lights could be completely off.  This system is competitive with the cost of hardwiring timers and dimmers.   And I've never seen dimmable timers.  You could save at least 30% of your hallway lighting cost.  Still, I'd wait until these bulbs come way down in price.  

Thursday, October 4, 2012

Product Design and the Fluidmaster Leak Sentry FAIL

Here's a common sense tip when shopping at Home Depot - be very suspicious of buying any product when all the units on the shelf look like they have been returned:

Notice the shabby condition of all the boxes on the right.  The product is obviously a market failure.

It's a great idea - a toilet valve that alerts you to a flapper valve leak.   But somehow the way Fluidmaster has implemented it has turned off customers in a big way.

The Hydro-Clean model on the left is a copy of the Fluidmaster design, and doesn't appear to work much better.   The boxes are fresh only because it was recently introduced.

Now a little commentary on product design and market testing.   Fluidmaster could have saved themselves this costly market failure if only they had gotten a couple thousand out into the field for well-documented feedback.  They probably tested the heck out of these to make sure they worked as designed, and found it was a robust design.

But here's the problem:   They work DIFFERENTLY than what customers are used to.  Sometimes different gets rejected by the market even when it's better.

Thursday, August 23, 2012

LED Lighting Update

IKEA has finally put its purchasing power and design talent toward LED lighting.

I think they hit it out of the park, and did it a year ahead of Home Depot.   In the catalog, they mention that the bulbs never need replacing.   Nice.

Saturday, July 28, 2012

Solar Thermal for the Masses

For a few years now, I've independently been trying to solve the problem of solar domestic hot water (SDHW) systems that are too expensive.  Here's what I've come up with: a simple and cheap solar hot water system design that at the very least should give manufacturers food for thought.

The Problem:  Even small SDHW systems cost way too much ($6-$8k on average)
Since gas heated water is still very cheap, the average family can only save $30/month with solar.

My Opinion:  The US SDHW industry is in deep trouble now, and will remain so until $2000 systems are available. 

A Solution?:  Bring back Recirculation for Freeze Protection (RFP) in all but the coldest climates in the US.

History:  RFP is still used in many non-freezing climates, so it's still a free option on most solar thermal controllers. It's reliability took a hit in the 80s when many systems froze because power failures often accompanied freezing weather. (Freezing rain will often take down power lines) Because of this, most installers eschewed this method for most climates. Historically, it can't be used with flat plate collectors because in the winter it takes too much energy to prevent the collectors from freezing. (They are pointed at the night sky which is usually colder than -100F on a clear night)

Why This Solution Can Work: A. If Evacuated Tube (ET) collectors are used, the heat required for freeze protection is almost negligible, and B. In case of a power failure, the system will self-freeze-protect by thermosiphoning. C. The outdoor piping is freeze and stagnation tolerant hose.

Yes, the ET collector header can still freeze and break, but the probability will prove to be too low to worry about. (Drainback systems have a few failure modes including freezing, but we still use them because the Mean Time Between Failures (MTBF) is long enough.)

I've tested this system for two winters now, and it works great in Denver. Here's a link to the YouTube tutorial about the system.

For more info and pricing, here's a link to my presentation at the 2012 ACEEE Hot Water Forum.

100% Off-the-Shelf:  Only  five of the items required must be purchased somewhere besides Home Depot:

1.   The pump:
2.   The Pump Controller:
5.   A 110V SPDT relay is also needed to control the ECV just right.

Tuesday, July 17, 2012

Just Say No to Twitter

It's an annoying fad that is a complete waste of time for the average person.   And time is your most important dwindling resource.  So cut it out.

Sunday, July 1, 2012

Plumbing Efficiency in New Construction: Using a Little Pipe to Save a Lot of Water and Energy

All of us have had the annoyance of waiting for hot water.   Whether it's to do a good job of hand washing or to get the morning shower over quickly, you know the feeling.

The conventional wisdom has always been to install a recirculation pump.   The best one available is probably from ACT:
It's a good solution, I guess the only problem is the cost, which is about $200 plus labor.

However if you pipe your hot water directly to each fixture with 3/8" pex, you have solved the problem.  But now you have to convince your plumber.

Gary Klein has developed a plumbing strategy that eliminates the need for a recirculation pump if the house you're designing isn't too damn big.  The strategy is called Structured Plumbing.  The reason it works is that there is very little water in the hot lines going to each fixture.  It's similar to "home run" piping.

Michael Chandler at Green Building Advisor has sketched for us what it means.   (Michael is uniquely qualified for that since he is a master plumber who designs and builds green custom homes)

Somewhat non-intuitively, it requires more pipe, which would be expensive with copper, but with PEX it's very easy and cheap.  PEX is very easy to work with,  especially in the 1/2" and 3/8" sizes, and is color coded.   Since it bends easily, you rarely need an elbow.   So you wind up using less fittings and more pipe.  That's OK, since the pipe is very cheap and should last 100 years.   In a small house, this extra cost is less than the $200 for the ACT pump, and it shouldn't need replacing during the life of the house.  Home Depot now sells the manifolds that make it even easier.

So thanks to Gary and Michael for giving us what will become the new standard method in residential plumbing.   If you're a builder, just hand this sketch to your plumber.  He may be a little reluctant at first, but if he's used to PEX he'll understand it quickly.   If he's not used to PEX, get a new plumber NOW.

Do you still need to insulate all the hot water pipe? Yes.   With insulation, the second person in the shower has instant hot water if there is less than 30 minutes between showers.

Wednesday, June 20, 2012

iCast Providing Much Needed Help to the Multifamily Industry

iCast has begun providing a win-win for apartments.   Most multifamily buildings are good candidates for money-saving energy efficiency measures.   Unfortunately, building owners often don't have a good way to find out the most cost effective upgrades, nor the money to implement them.

Here's a press release about the iCast program:

"iCAST, a Colorado based not-for-profit was recently awarded a 30 month cooperative agreement with HUD to establish an innovative program that provides new ways of making cost-effective investments in Energy Efficiency (EE) for the low-income multifamily housing community. iCAST is tasked with providing a simple, yet comprehensive program that achieves cost savings for owner/managers while creating a more comfortable and healthier environment for residents via an integrated suite of improvements, including energy conservation measures, behavior change measures, demand side management measures that reduce peak/demand charges, water conservation, indoor air quality, etc. The HUD award also offers a unique combination of incentives, rebates, and financing programs to owners and managers. iCAST designs solutions so that your investment pays for itself. You start saving money from Day 1! iCAST projects have reduced the energy bills of over 1,000 multifamily units by an average of 30%, while helping owner/managers hedge against rising energy costs, improve the value of their properties, and enhance the quality of life for residents."

Please note "behavior change measures".   That is an interesting topic unto itself.   Here's an example:
When you have "free heat" in your apartment, you might abuse it without even knowing it.   You might keep your thermostat at 74F all the time, and open a bedroom window for "fresh air".  Behavior like this can easily double the amount of heat that you use, causing your "affordable apartment" to be less affordable for the building owner.
"Behavior change", in this case, is training the residents to keep the windows closed in the winter to save energy.

Another example might be to train tenants to program and use a setback thermostat.  Many  tenants (usually the younger ones) are highly concerned about the environment will use them if given the chance.

Multifamily Energy Savings: The Conflict of Interest

There are thousands of multifamily buildings in the Denver area that need some energy efficiency improvements.   The most cost effective of these improvements are usually simple control upgrades.

One example of the "lowest hanging fruit of energy efficiency":

Steam boiler systems cannot be zoned with individual 24V thermostats in each apartment.   Therefore, one thermostat controls the whole building, and the location of that thermostat is critical.  In a 20 unit building on 19th Avenue, I found it in the main hallway.   Unfortunately, the main doors were always cracked open a little, and so the hallway was always cold.   Over the years the heat emitters (radiators) had been removed from the hallways.

Therefore, that thermostat location caused the boiler to be on all the time, and all the tenants were roasting and opening their windows all winter to shed enough heat to be comfortable.   This is known as the "double hung thermostat method".

So, for $600, I purchased a steam-compatible thermostat and installed it in a more appropriate location.  The savings are more than $3000/year and will increase as the cost of gas increases.

The average energy auditor doesn't know this stuff.

It can only be learned through field experience as a heating technician, but books from can get you half the way there.   They can be read and understood by almost anyone.

A typical building owner might have a building that seems to have a higher utility bill than his other similar buildings, but since he doesn't know heating controls, he is forced to call a contractor.  Here's the inherent conflict of interest.  Even if the owner tells the contractor "please try to reduce the gas usage of this boiler" the contractor is loath to do anything that might cause a comfort problem and a callback.   The contractor  isn't responsible for the heat bill, but if he touches or upgrades the control system, he is suddenly responsible for having enough heat for every apartment.  So that contractor is more likely to make every apartment 74F instead of the 68F that the owner would prefer.

Wednesday, June 6, 2012

A Quick Look at the Near Future of Renewable Energy

 Solar Thermal may be dead: http: //

But PV will reach grid parity soon:

Even though right now it's in the midst of a "correction":

Cheap gas is delaying renewable uptake, but using gas for making electricity inherently has a VERY low overall system efficiency, and seems a waste of a non-renewable energy source.

Conclusion: Inevitable but rocky growth for PV, with a Darwinian edge.

By the way, Jay Burch et. al. at NREL are trying to save solar thermal by finding a technology that provides a "disruptive cost reduction". Here's an abstract of a forthcoming report:

"Executive Summary

The objectives of this report are to:

(1) Identify the target market for solar hot water heaters that will provide the largest U.S. energy savings potential relative to other advanced hot water heating technologies, and, (2) Identify potential technology pathways and cost/performance targets that must be met to enable solar hot water heating systems to achieve large energy savings.  The market environment for solar water heating technology has changed substantially with the successful introduction of heat pump water heaters (HPWHs). The addition of this energy-efficient technology to the market increases direct competition with solar water heaters (SWHs) for available energy savings. It is therefore essential to understand which segment of the market is best suited for HPWHs and focus the development of innovative, low-cost SWHs in the market segment where the largest opportunities exist."

Tuesday, May 29, 2012

Don't Worry About Swamp Cooler Water Consumption

People sometimes worry about the water consumption of an evaporative cooler.   I found this information in an NREL report:

"on a Btu-of-cooling-per-kWh-of-electricity basis, the best evaporative cooling systems are on the order of five times more efficient than SEER 13 central air conditioning (CAC) systems and demand is less by a factor of four or more. Further, additional water use at the site (home) amounts to only about 3 percent of the water use of an average residential customer."

So don't let water costs drive you away from swamp coolers in Denver.

However, if you are building a new, smallish, superinsulated low energy home, you are better off going with a mini-PTHP for heating and cooling.  A swamp cooler requires more maintenance and seasonal mode changeover, which is awkward due to seasonal overlaps like "Indian Summer".

Thursday, May 17, 2012

Reports From the Field - Part I - Zone Valves in Apartment Buildings


Recently I have been performing energy audits of mid-size multifamily buildings, focusing on control problems, the true "low hanging fruit" of energy efficiency for these apartment buildings.

The most common problem we are seeing is zone valves that fail "open".   Tenants will not report this or complain about too much heat until summer.   In summer, no one is looking for boiler problems, and oftentimes the boiler is off for the summer, problem solved unknowingly.

This is not a trivial problem.   Just one zone valve that is fully open all the time in a building with constant circulation will waste at least $30/month.   We've seen 20 unit buildings using $100-$300 /month too much gas when this condition is present.

Landlords are cheap, but here's a situation where you have to spend a  little to save a lot.  The payback period will usually be under two years.   And don't forget:   Every $1000/yr saved in expenses makes your building worth $14,000 more in today's market.

Your average contractor isn't on the lookout for leaky zone valves.   He just wants heat in the apartments and no complaints.   And I can't tell you the reason, but Xcel Energy's energy auditors aren't trained to find problems like this.   

So that means you have to call me.  (720 435-5909)   Another guy in Denver who is great at this type of detective work is Mark Eatherton at 720 375-3107.

Here are my general recommendations:   

  1. If you think that your zone valves are more than 20 years old, replace them ALL.   Seriously.
  2. If they are more than 12 years old have someone check them out to see if any are leaking through.
  3. If you have the 3-wire style zone valves "White-Rogers" more than 12 years old, replace them ALL with Honeywell or Erie valves.   It's not that they are  unreliable, they are just harder to work with.   The average maintenance technician has no idea how they work, so he can't troubleshoot them, and thus you will have to call a more experienced (read expensive) heating tech.
  4. If you suspect your building is using too much gas or electricity, request a usage report from Xcel.  Contact the Building Solutions Center at  or call  1-800-481-4700  .   Then email it to me at and I will compare it to similar buildings and let you know if I think you have any problems.
  5. Don't stop there.   Have your consultant look for other energy wasting issues - more on them later.

Tuesday, March 20, 2012

Denver's Street Grid is Efficient, Charming and Shouldn't Have Been Abandoned

A Rectilinear street grid is usually the most efficient layout for a city.

However, my observations of cities haven't convinced me that the grid is always the best form.  If you have lots of mixed use and high density, a grid makes destinations easier to find, and its porosity makes the perfect pressure relief valve for those peak traffic times.

Paris, Rome, and Sydney don't have grids.
They are interesting and walkable.  Historically, they were a bit hard to navigate for the newcomer.  GPS has fixed that, even for pedestrians.  Their streets grew organically around the topography and without much planning.  A grid for them would increase utility at the expense of charm.

There's an old neighborhood in Denver called Bonnie Brae that was planned in about 1910 and built out over the next three decades.  It has curvilinear streets, a diagonal collector road, but no cul-de-sacs.  It was designed this way because the private developer thought it would be more interesting, charming, and exclusive than the surrounding grid neighborhoods.  He was right, even though many backyards were reduced to skimpy triangles.

In the 50's & 60's this charm was noticed by the suburban developers, and they replicated the style in their new automobile suburbs, added gates, cul-de-sacs, and high speed perimeter thoroughfares.  The charm and walkabilty were utterly destroyed by the car-centric design.

So the grid makes city planning and development easier and more predictable, but folks will eventually get a little bored with it, and it doesn't make a better city by itself.

PS.  Don't ever make Denver's mistake of putting in one-way streets to expedite traffic.  Most of them have been put back to the way they originally were, two way.  Also never give in to the folks who live close to the thoroughfares and want traffic on their streets to be limited some way.  The extra traffic they suffer with a couple hours per day causes greater benefit of reduced congestion for the city as a whole.

Saturday, February 25, 2012

Beyond Net Zero?

Now that a run-of-the-mill homebuilder can offer a net zero energy cost home, you might consider going beyond net zero.  Your house could generate more energy than it uses, and actually put money in your pocket.

How much could you make?  Well, according to these rules,  you can't install more than 20% excess solar capacity, and they will only pay you wholesale prices for it:

Net Metering shall be, for billing purposes, the net
consumption as measured at the Company’s service meter.
However, in the event net metering is negative such that the
Eligible Energy Resource’s production is greater than the
Customer’s consumption in any month, the Company will not
credit Customer for such negative consumption. The negative
consumption shall be considered as energy available to offset
consumption in subsequent months. However, in the event that
such negative consumption balance remains at the end of a
calendar year, Company will pay Customer for such negative
consumption balance at the rate that reflects the Company’s
average hourly incremental cost of electricity supply over the
most recent calendar year. Payment shall be made within sixty
(60) days of the end of each calendar year, or within sixty
(60) days of when the customer terminates its retail service.
Customer may make a one-time election, in writing, to have the
Company carry forward the Customer’s negative consumption as a
credit from month to month indefinitely until the customer
terminates service, at which time no payment shall be made by
the Company for any remaining negative consumption balance.

For new construction, you could make a high guess at your consumption, and maybe get away with more that the 120% limit.

Wednesday, February 1, 2012

Simplest Split Solar System Ever?

As you may know, I was originally trained as a Solar Engineer (solar water and air heating).  In the early 80's, we learned a lot of things on our own because:

1.  Manufacturers supplied only components, not complete systems.

2.  Because every house is different, every installation is unique, causing mistakes and "issues".

In my opinion, the solar water heating industry has still not  matured.  Because systems currently cost too much, they aren't being installed as often as they should (which is on every house in the Denver area).  For high volume uptake to occur, NREL says the installed price needs to be between $1,000 and $3,000, not the $6,000-$11,000 that you typically find.

Recently, I've been back to learning things on my own, and collaborating with folks like genius Steve Baer.
Some of us have been working on solar system simplification.  One simple domestic hot water system that  has tested successfully is depicted in the video on YouTube below.   If your house has the right configuration, I can install this system for you for $1850-$2600 with a 5 year warranty.  It may be simple, but it requires some high tech to succeed.  The collector we must use has the lowest heat loss coefficient of any mass marketed panel.

Monday, January 30, 2012

CFLs Suck Update

There is quite a bit of anecdotal evidence that CFLs can cause seizures, rashes and cancer.

I know some people who "hate the light" from CFLs.   Since the color problems have been mostly solved, I think the subliminal flickering is what they object to.

Unfortunately, these problems are also shared with high performance T5 & T8 fluorescent tubes, which are very efficient and economical.  Affordable and long lasting LED tube replacement bulbs are coming eventually, so I'd still recommend tube fixtures where appropriate.

Thursday, January 12, 2012

Single Family REITs

If you have been following this blog, you know that I'm advocating the rebuilding of "inner ring suburbs" vs. new subdivision development.

A new report from Morgan-Stanley picks up on a trend I've noticed in the past few years in Southwest Denver:
That rents are now much higher than ownership costs.

Right now is a rare time in history that institutional investors can make an exceptional return by investing in single family homes.

When it's time for the REITs to sell their assets, the idled large homebuilders are the logical buyers.