Saturday, November 15, 2014

The Shirley Wall is Gaining Traction

There has been a lot of talk recently about the Shirley Wall, which could be the simplest known way to build a high R value wall.

There is an assortment of videos that chronicle the building of this house at YouTube:

Monday, October 27, 2014

How Much Money Can You Save by Installing all LED light bulbs?

Well,  Xcel Energy has already done the math for me:

"Amount of Electricity Used
We’ll need to begin with the amount of light bulbs in a home. According to a recent survey, the average American household uses 47 light bulbs.
Now, these bulbs might have varying wattages from 100 watts down to 25, but for the sake of easy math and comparisons, let’s assume that we are using all 60 watt bulbs.
Total Light Wattage = 47 bulbs X 60 watts = 2,820 watts
That’s a lot of wattage!  Now let’s take a look at the wattage if all 47 lights are CFL bulbs or LED bulbs at the equivalent brightness of 60 watt incandescent bulbs.
All bulbs deliver equivalent brightnessSingle bulb wattage Wattage used for whole house
Incandescent bulbs
60 watts
2,820 watts
CFL bulbs
14 watts
658 watts
LED bulbs
10 watts
470 watts
As you can see, there is quite a difference in the wattage between energy efficient bulbs and incandescent bulbs.  In other words, switching to CFL or LED bulbs would save A LOT of energy.  And as I’m about to show you, this will, in turn, save a lot of money!

Cost of Electricity
The average cost of electricity in the United States is currently 11.88 cents per kilowatt hour (kWh) (for a more accurate cost, you can check your last billing statement for your cost per kWh), meaning if you used 1,000 watts of electricity for an hour, it costs you 11.41 cents.

Time that Lights are Turned On
The amount of time the lights are being used can vary quite a bit from home-to-home, but let’s pretend, for the sake of this example, that each of us use our lights for 5 hours a day. That’s 30 days in a month (on average), for 5 hours a day.
5 hours X 30 days = 150 hours

Now that we have all of the necessary factors, we can calculate the difference in cost of using traditional incandescent light bulbs versus energy-efficient CFL and LED light bulbs. The formula for this is below:
kW used X (Cost per kWh) X Hours Used = Monthly Lighting Costs
Remember, a kilowatt (kW) is 1,000 watts, so we divide our wattage by 1,000 for this formula.

Monthly Cost of Using Incandescent Light Bulbs
2.820 X $0.1188 X 150 hours = $50.25

Monthly Cost of Using CFL Bulbs
0.658 X $0.1188 X 150 hours = $11.73

Monthly Cost of Using LED Bulbs
0.470 X $0.1188 X 150 hours = $8.37
 If, in this scenario, I switched 47 incandescent light bulbs to LEDs, I could save around $41.87 each month. That really adds up over the course of a year, and the savings continue to grow over many years."
Most households probably aren't using quite that much energy just for lighting, so you should consider the above example a "best case" scenario.
IKEA is now selling a dimmable A19 bulb for only $4.49 plus sales tax.  So if this bulb were appropriate for every fixture in the house above, the total cost to refit the entire house would be only $226, with a payback period of less than 6 months.  That's still a great investment even if you only use your lights half that much.  
The fact that these bulbs are supposed to last for over 20 years, makes it even a sweeter deal.

Friday, October 17, 2014

Slabs vs. Crawlspaces

As mentioned previously, slabs get the nod as the greenest foundation strategy.

"The tipping point in favor of slab-on-grade over crawlspace is that the slab can be the finished floor. Stained concrete is still trendy, bulletproof, and saves at least $3/sq.ft. on your floor system.

My concrete floor is six years old, had zero maintenance*, and looks just like the day we moved in.

The thermal mass and the way it buffers the temperature is just a bonus."

This floor has an oil-based polyurethane finish, which should work for you if the slab is truly decoupled from the soil.

Tuesday, October 14, 2014

Grid Defection Will Make More Sense if Net Metering is Compromised

Going Off-Grid in the City
1. Net zero homes are usually all-electric, and already are off the natural gas grid.
2. Misguided utilities and PUCs may ruin net metering. This makes it desirable to go off grid if your climate is sunny enough.
3. Batteries can provide daily backup.
4. A propane generator is currently the most logical off-grid backup electric source for long sunless periods.
5. If your climate isn't sunny enough, or if propane prices increase too much, then you may want to get back ON the natural gas grid.  You'd do this to minimize your backup electricity costs during cloudy winter months by using an automatic natural gas powered generator.
A comment about home design:
An off-grid house needs a much steeper tilt angle for the PV panels, to produce more in the winter and not over-produce in summer. This has another benefit of shedding snow better.

Wednesday, October 1, 2014

Denver's "War on Cars" is Real and Cars Will Lose

Here's a good summary of the controversy from Streetsblog USA:

Denver Urbanists vs. Traffic Calming Conspiracy Theorists

With a fast-growing transit network, Denver is grappling with how to build walkable places around its new rail lines, and the Denver Business Journal is running a package of stories about the potential for transit-oriented development. Overall it looks like a solid introduction to the notion that Denver needs to reduce car dependence, but the series did take an unfortunate detour into “war-on-cars” fantasy-land today with a he-said/she-said piece titled ”Are transit-oriented developments a campaign against cars?”
Transit oriented development isn't a conspiracy against driving, it's an attempt to level the playing field for other modes. Photo: City of Denver
Guys, this is not a conspiracy against the middle class. Photo: City of Denver
Still, it’s helpful to get a reminder of what urbanists are up against in cities like Denver. In this case, the “debate” started with a Denver Post column by City Council President Mary Beth Susman published in June. In a fairly moderate plea for better transit options, Susman noted that in addition to providing incentives — “carrots” — to entice folks to try walking, biking or transit, the city is planning to use some disincentives — “sticks” — to discourage driving. The two “sticks” she mentioned were reducing parking requirements — we’re talking about loosening government regulations that compel  – and refraining from widening roads in some areas of the city.
In response, the conservative Colorado Peak Politics called Susman’s editorial an “astonishing” admission that the city’s policy was trying to “actually make driving inconvenient.” The outraged, anonymous blogger asserted that nobody with kids to drop off, or a “client-facing position,” or groceries to pick up will ride a bike in Denver, and that policies that try to make biking safer and more practical are a “dangerous” attack on the middle class.
But the real hidden gem of this whole episode comes from Kathleen Calongne of the sprawl-loving American Dream Coalition. While it’s regrettable that Business Journal reporter Caitlin Hendee treated Calongne as a credible source, she’s at least good for some laughs.
“Research reveals that traffic calming projects are often motivated by individuals in our federal and local governments willing to sacrifice safety in an effort to discourage travel by car,” Calongne claims. Exactly what is motivating national and local government leaders to mislead the public in their quest to make driving worse, she doesn’t say. She does, however, go on to argue that traffic calming and transit-oriented development are bad for people with disabilities and the elderly.
Calongne doesn’t specify what research backs up her claims, but her credentials appear to consist mainly ofthis ancient article hosted by the National Motorists Association, purporting to show evidence that traffic calming harms people. Even back in the early aughts, when that article appears to have been published, there was ample evidence that traffic calming saves lives: A 1997 study [PDF] published in the Institute of Transportation Engineers reviewed 85 studies of traffic calming cases in Europe, North America, and Australia and found a decrease in collisions ranging from 8 to 95 percent.

A Simpler, Foam Free "Perfect Wall"?

I’m still researching wall and roof/ceiling assemblies because I haven’t been totally happy with anything I’ve tried yet.

in some areas of the country, especially in the Northeast, insulation contractors have been dense-packing unvented rafter bays with cellulose for years.”

Then I discovered a project by David Posluszny in Shirley, MA, that used a simple, very easy to build double wall section.  From inside to outside:   Drywall, netting, 12” of cellulose, plywood sheathing, (Henry Blueskin), furring, wood siding.

Since intra-wall condensation was a concern, he did some moisture testing after an extreme cold spell: “With the help of Bill and Jim from National Fiber, we tested my wall assembly. We took moisture readings in North, South, West and East walls, checked the moisture gradients, lofts, and crawlspace. We are pleased to find all the moisture levels came back well within comfort zone. This wall assembly works.”

David actually used Grace Ice and Water Shield as the air and weather barrier, but as he mentions in the video, Blueskin would accomplish the same tasks, is cheaper, and is vapor open.

This is an extremely tight house.  It’s possible that this wall section could develop moisture problems in leakier house.  However, David and the insulation suppliers emphasize that dense packed cellulose mitigates moisture problems in two ways:  It retards air movement and redistributes moisture because it is hygroscopic. So this could be a very robust assembly that can tolerate sloppier air sealing than what David has done.   (0.1 ACH 50 might be some sort of record)?  

This assembly also solves the tricky problem of how to air seal at the eaves where trusses meet walls.   The trusses don’t include the eaves, which are built after air sealing.  By laying 2x4s flat on top of the first layer of roof sheathing and covering  them with another layer of plywood, he ensures that shingle nails will never penetrate the air barrier and the cold roof has generous venting:

Some more features of this wall:

1.  Since all the air sealing is done at the exterior weather barrier, no air sealing is required for the electrical work.
2.  The air and weather sealing is done in one layer, which simplifies everything and reduces cost.
3.  The self adhesive air barrier has no penetrations due to staples.

The Problem

The theories behind vapor diffusion in walls would show that this is a risky assembly.  In practice, however, the wall seems to work.  Apparently cellulose can pull moisture from the inside of the exterior sheathing and release it back into the house as fast as the condensation occurs.

The next step would be to prove this in the lab and in the field.  This would be worthwhile because I don’t think there is an easier or cheaper way to build an R42 wall.

Friday, September 12, 2014

Dual Hose Portable Heat Pumps Don't Work Well in Practice

For years I've wondered if a dual-hose portable heat pump/air conditioner would work as a poor man's ductless minisplit heat pump. The advantage, as my logic went, was that I didn't have to drill any holes or charge any refrigerant.
I bought a 14kbtu portable heat pump (Edgestar AP14001HS Portable Air Conditioner)
I did some primitive temperature and airflow measurements.
I was impressed by the overall quality and the 11.2 EER, but what I found was very disturbing.
There is so much internal leakage, that the heat pump blows almost twice as much air out of the house that it pulls in. That difference in air volume gets sucked from outside into the house. The net effect of that is to reduce the COP in heating mode from the advertised 3.3 to roughly 1.4.
For heating, that makes it hardly worth the extra money over a resistance heater. I might as well have purchased an electric resistance heater with a COP of 1.0. In the air conditioning mode, this problem makes the unit worthless except for spot cooling. A window unit would work three times better at a lower first cost.
Has anyone seen a dual hose unit that actually works well?

Monday, September 8, 2014

Pretty Good Duplex HERS Scores

We just finished and sold both units of a spec duplex in SW Denver.  The HERS scores were "pretty good" at 59 and 62.

One of the more important components of the HERS score is the infiltration measurement.  Building Joe Lstiburek identifies 3.0 ACH50 as a pretty good goal.  We scored a 3ACH50 without trying very hard.  The main reason for the good score was the "flash and fill" insulation strategy.  About 3 inches of polyurethane spray foam was sprayed on the inside of the sheathing, and the rest of the cavity was filled with cellulose.

Did the HERS score even come up during the sales or marketing process? Not at all.   Was it good experience for our building professionals in anticipation of the IECC 2012 requirement of 3.0 ACH50?  Absolutely.

Heat Pump Dryer Update

Apparently production of the LG heat pump dryer for the US has been stalled.  A call to customer service yielded no knowledge of it.

But now there is a report that Whirlpool will have one available Q4:

Friday, September 5, 2014

LED lighting update 2014

The LED bulb market is still changing quickly, but IKEA has a 600 lumen dimmable bulb for half the price of the 60 watt equivalent Cree:
The Cree bulb is on the shelf at HD for $9.97:
The Cree is 84 lumens/watt and the IKEA is only 60 lumens/watt, so the Cree pays for itself in 3yrs, assuming 3 hours usage per day @ $0.13/kwh
My wife also thinks that the Cree can go dimmer.

Tuesday, July 29, 2014

Update: Combination Washer/Dryer from LG

LG still makes the only full-size washer/dryer combo available in the US.  They have discontinued the old one that I discussed previously.  A new model is now available.   I like combos because you never have to move the clothes from the washer to the dryer, and they save space.

Sunday, July 13, 2014

Bad News for Home Depot Devotees in Denver

I had an estimator from Home Depot come to my office to bid a minisplit installation.  It was the same as calling ARS directly.  He said that all their installations, even for a small 9kbtu unit, start at $9,000 and go up from there.

Saturday, June 7, 2014

Is the "Sharing Economy" a Green Strategy for Denver?

When it comes to housing, airbnb is the most important player in the sharing economy.

Airbnb is a very useful tool to help a building owner eke more money out of his investment. More income means his investment is more sustainable.  The visitors and tourists that use his accommodation will spend money in the neighborhood. That makes the local businesses more sustainable.

Having thousands of airbnb hosts makes a growing city more sustainable because it means that fewer new hotels need to be built. New hotels place a large added burden on the utility infrastructure.

Some cities are resisting the new realities of the sharing economy, and are hampering its growth through unnecessary regulation.

For many years, Denver's zoning law has prohibited homeowners from having lease periods of less than 30 days.  This law has been challenged in Park Hill, but the law prevailed.

Today, Denver's neighborhood leaders tend to be the type of people that want to "preserve neighborhood character".   They do not like short term rentals.  City Council President Mary Beth Susman understands the "sharing economy" and has begun the discussion.   Stay tuned.

The Future of Residential Heat Recovery is Ductless

I just took ownership of the first ERV to be sold at Home Depot
Price $431
Extra stuff I learned about it once I got my hands on it:
1. The 16cfm mode, medium, (perfect for a 2 person bedroom) is only 0.3 sones at 4 watts. Almost inaudible.
2. Low speed is 8cfm (the one person setting) is 0.1 sones which is TOTALLY inaudible.
3. It can cycle on humidity if desired. That is, it will come on when the humidity reaches 45%RH (low), 55% (medium), or 65% (high). If the indoor humidity exceeds the set point, the unit is switched to high speed.  If the indoor humidity is within 5% of the set point, the unit operates at medium. If humidity is 5% below the set point, the unit switches to minimum speed.  This sounds like a reasonable control strategy for winter, but in the dry Mountain West, it would always be on low speed.  It sounds like the wrong control strategy for summer.
4. It pretty much is a ripoff of the Lunos design, but I don't know if either design is patented anyway.
It's not synchronized like the Lunos but I believe synchronization is unnecessary, and actually reduces the total house airflow.
5. The US distributor, Zoltan, will give a quantity discount, which gets it down to a price I can justify in new construction spec homes and rentals.  With a name like that, he knows all about predicting the future
6. The exterior vent cover is an elaborate, good looking, bomb proof fabrication of stainless steel.

7.  When the unit is off, it has a high quality, very tight powered plastic damper.

In my opinion, if the bedroom doors are left open except at bedtime, Fick's Law of Diffusion will ensure that fresh air will reach the rest of the house.   (The average speed of an air molecule flying around the room is 500m/s)  That means a three bedroom house may only need 3 total units.

Other important things that should be mentioned:
A.  Perfect zoning
B  Dead simple commissioning.
C.  Wires are easier to run than ducts.
D.  More total holes in the walls. (Bad)
E.  Inherent frost protection.

Tuesday, April 15, 2014

Car 2 Go Now Offering Regional Access

Called Moovel, now all North American car2go members can use the car2go service in any of car2go’s 13 cities across the U.S. and Canada:

Columbus, OH

Denver, CO
Portland OR
Austin TX
Washington DC
Southern Los Angeles area  CA
Toronto ONT
Miami FL
Vancouver BC
Seattle WA
Montreal, Quebec
Calgary, Alberta
San Diego CA

Expect a similar offering soon from Zipcar, Hertz 24/7 or similar company.  The convenience of Car2Go will erode their market share until they react.

Note - San Francisco is not covered, partly because of parking issues.  Apparently SF thinks that car sharing is less green than mass transit, even though one Car2Go can take 15-20 conventional cars off the street.

Tuesday, March 4, 2014

Clothes Dryer Efficiency Update- LG Releases Heat Pump Dryer for US Market

The holy grail of clothes drying technology is the heat pump condensing dryer (HPCD), and we are finally getting it.  If your family does a lot of laundry, this will pay for itself, even though it is pretty expensive at over $1500.

Consumer Reports neglects to mention the fact that there is no hole in the wall of your house.  Conventional dryers blow  heated air from the house to the outside in the winter, which effectively doubles their energy usage. This heat isn't measured in dryer tests, because the heat is provided by the house furnace.  So an HPCD actually uses four times less energy than a standard electric resistance dryer.  In addition, that hole in the wall can lose a significant amount of heat even when the dryer isn't running.

NOTE 7/13/14 - This new dryer from LG is not available yet.

Friday, February 7, 2014

The Great Ventilation Debate Rages On

The best minds in the building science field have not been able to yet agree on a ventilation rate for residential buildings.  The Energy Vanguard Blog is the best spot to witness that ongoing debate.

In my view, setting a standard for the ventilation rate is completely the wrong approach.  

As an analogy, consider the heating temperature control for a house.  If the temperature drops below a user-defined comfort setpoint, then heat is added to the space.  That's very simple, easy, cheap, and effective. Thermostatic control of  space heating can hardly be improved upon.  Why does it work so well?  Because it MEASURES, then CONTROLS.

In space heating, what we DON'T do is add a fixed number of btus per hour to the space during the winter season.  Yet that is what the ASHRAE or BSC ventilation standards propose to do*.  The current "cfm/person" approach is pseudoscience and should be abandoned in favor of  measurement and control.

What should we measure?  We're not sure yet, but if cost were no object, we would measure CO, CO2, methane, humidity, radon, and VOCs.  We may find one of these that can be a proxy for some of the others.

With that "air quality control" in place, the occupant can dial in a preferred setting, then forget about it.  The house will then get only what it needs, and there will be no money wasted on over-ventilation.

Ah, but we can't trust air-quality-ignorant occupants to know the best setting, right?  No, we can't, because many of the airborne contaminants cannot be detected by human sensory systems.  There is an obvious solution to that also, just ensure that the controls have scientifically derived maximum concentration settings for each contaminant.  Back to the space heating analogy:  thermostats have a minimum setting of 45F because bad things (freezing pipes) can happen below that setting.

*A standard ventilation rate can't account for all the variables.  Consider this:  what if the outdoor air is actually worse than the indoor air?  In that case, ventilation is the wrong answer, and a smart control would shut off the ventilation.

Tuesday, February 4, 2014

Living with Car2Go

Let's say you have a net zero energy home.  That's great.

But if you are still driving 20,000 miles a year, you are using way more energy than a carless person living in an old, energy-hog house.  So in order to live truly sustainably, you have to think outside of your box.

Cities are very energy efficient places to live, mainly because you can walk, ride a bike, or drive a very short distance for most things in your life.  Two of the most annoying things about living in a city are traffic, and finding a parking spot at your destination.  Therefore, city living becomes more enjoyable if you can live without a car.  As cities become more dense, cities must find ways to help their residents wean off of cars.

Real estate in cities is just too valuable to use for storing cars and for providing wide streets.  Since we only use our cars for 1-5% of the day, why are we paying to insure and store them the rest of the time?  Car2Go isn't a perfect solution yet, but it's an extremely convenient and successful way to help us share our cars and reduce the number of cars we need to store in the city.

Claire Martin of the Denver Post wrote a great article that describes the reality of using Car2Go, RTD and BikeShare rather than owning a car.