Monday, August 19, 2013

Nearly Everything to Know About Building Green

Martin Holladay's list of articles is very complete, and the comments section is also extremely helpful:
http://www.greenbuildingadvisor.com/blogs/dept/musings/how-do-everything

This list is continually updated, which is good, since the field is always changing.

GreenbuildinginDenver aims to fill in the blanks for Colorado's Front Range, and add topics where our expertise is helpful.

Check it often for the most unbiased and accurate methods to save energy in residential design and construction.

Sunday, August 18, 2013

Pin Foundations: A Very Green Foundation System

Here is a very  inexpensive and non-invasive foundation system that is slowly gaining popularity.  What is holding it back is typically conservative builders and structural engineers.

http://www.pinfoundations.com/green.htm

If your jurisdiction requires a soil report, then you may be able to find a geotechnical engineer who can work with the engineers at Pin Foundations and get the structural plans stamped.

The floor insulation and moisture vapor control details are important:  http://www.pinfoundations.com/docs/DP%20SKIRT%20WALL%20PRL%20TO%20JOISTS.pdf

In most cases, this system means:
1.  No excavation contractor
2.  No poured footings
3.  No concrete forming or stemwalls
4.  No concrete delivery trucks using diesel and disposing of waste concrete

Since the system eliminates conventional concrete work, many would consider it very green.  Concrete work is still tolerated by most green builders due to its durability and longevity, but the concrete industry is apparently one of the top contributors to global warming.

Monday, August 5, 2013

Saving Water and Floorspace

Maybe you've seen those toilets that save water by incorporating the handwashing sink into the lid of the toilet

There is also a way to retrofit a sink to the top of most side flush toilets for $140:


I like this idea, because I think you could save room in a house by putting the toilet and a shower in a smaller than normal bathroom, and have the main bath sink hovering in the bedroom as IKEA suggested in last year's catalog.   This reduces collisions between the two people sharing a three piece bath.  Saving water by reusing it is good too.

Also, some may criticize this toilet-top-hand-washing idea because there is no hot water available.  Well, most people don't wait for hot water at a conventional bath sink anyway.

Sunday, July 21, 2013

Car2Go is Free Until August 4th

Now You Can Go Carless Painlessly - -

You've probably already seen the blue and white Smart Cars sitting all over town with keys in the ignition. Once you've signed up, you can take any of them for a few minutes or across town and then leave it anywhere in Denver. No reservation needed.  Your smart phone instantly shows you where the closest one is.

For longer trips, sign up for E-Go CarShare, but you have to return it to their special spot.

This means that you can design your garage to store your stuff, and you don't need to pretend that your car will use it.

Tuesday, July 16, 2013

Finally an Unvented Washer/Dryer that Works Pretty Good

The status quo method of drying clothes inside a house is a lousy method.  If you use an electric dryer, you are buying expensive heat to raise the temperature of the dryer airstream, and then you blow that air directly outside.  Whenever you blow air out of the house, it must be replaced with unconditioned air from outside.  So using your dryer causes you buy about twice as much heat as the dryer actually uses.  The hole in the side of your house for the dryer vent also tends to make the house leak more air than if you didn't have that hole.

"Heat pump dryers" are the most efficient way to dry clothes, but we can't buy 'em in the US yet.

"Condensing dryers" are currently the best alternative we have.  They dry the air by condensing the water vapor out of the air rather than blowing it outside.

LG and others make "combo" units that combine a washer and condensing dryer into the same appliance.  Not only does that save a lot of expensive real estate inside your house, the user doesn't have to transfer the clothes from the washer to the dryer.  Put your clothes in at night, wake up to clean and dry clothes. Cool.

I've been following the development of these appliances for 10 years, and found that they were unacceptable because they never got the clothes dry enough.

LG has a new model that seems to work.  The online reviews are by far the best I've seen for any washer/dryer.

So your new house can be designed without a dryer vent, which is a win-win.

Monday, July 8, 2013

Vacuum Insulation for Walls now Available

Dow has developed a very interesting product that achieves R39 per inch, which leapfrogs even aerogel in insulating performance:
http://www.dowcorning.com/content/publishedlit/62-1556-01.pdf

It is also close to the theoretical limit for insulation space efficiency.  In a superinsulated home, this insulation can add 10% to the usable size of the home for a typical exterior footprint (because the walls can be thinner).  In a typical situation, that's a $15/sq.ft. savings.  Currently, I'm sure that this stuff will cost much more than $15 per finished square foot of home, however, so we have to wait until production costs come down.

The production costs can theoretically be very low, since it is apparently just a high tech bag of sand.  Vacuums contain nothing, so they can be made very cheaply with the right production equipment.

Drawbacks are that you can't cut or drive a screw through it since both operations cause loss of vacuum.  Hopefully, Dow engineers are working hard on those major issues.

Idea- The panel production could be on-site with a machine capable of producing custom sizes.

Tuesday, June 11, 2013

Chimneys Are A No-No

Wood burning masonry fireplaces, while they used to be desirable in homes as recently as the 20th century, are an energy efficiency disaster.  (Direct vent woodstoves are usually OK)

Gas fireplaces can be less of a problem, but they are usually vented with a metal pipe of some sort.

Therefore, every new chimney you've seen in the past 20 years is a FAKE chimney, stuck on by an architect or home designer who thinks it's necessary to "make a house look like a home" or whatever.

Stay away from fake and real chimneys because they hurt the integrity of your insulation and air sealing layers, and compromise the durability of your roof.  In my ownership and maintenance of 200 or so homes in the Denver area, chimneys are the most common location for roof leaks.

Friday, February 22, 2013

Off Peak Cooling in Colorado

As you study the costs of electricity generation, you find out that Xcel's cost go up sharply during hot summer afternoons.  Back in the days of off-peak, or TOU, rates, PSCO tried to pass the extra cost on to the customers.  This pricing scenario has faded out over the years, but may come back.

Evaporative cooling works best at night, so you can accomplish off peak cooling by overcooling your house at night  and in the morning.  The cheaper coolers hardly work with a daytime temperature above 86F anyway.  The thermal mass of your house will then let you coast through the afternoon without using air conditioning at expensive rates.

Wednesday, February 20, 2013

Green Backup Power

After Hurricane Sandy, having a backup source of power for your home has become more important to some people.  Using a gas generator is one option, and they are very economical to buy, but not necessarily to run.  After Sandy, it was tough to find gasoline.  Another option is to have a permanently installed natural gas generator, but this isn't a good option in an all-electric home.

If a lengthy power outage ever hits Denver, those of us with large PV systems will be kicking ourselves for not installing an easy way to go off grid.  You see, all the PV systems you see on private houses currently DO NOT WORK if the grid is down.  The average refrigerator has $200-$300 worth of food in it.   I'm allergic to most candles, and they are a great way to burn your house down, so backup electricity would be nice.

I'm sure that the big power purchase agreement providers, SunRun and Solar City, are working on this, and I'll post the answer here when I get it.

EDIT 3/18/13:  The inverter company, SMA, will be releasing a new inverter that has this functionality.  It will have "an emergency power supply to provide daytime power in case of a grid outage".
This is expected in 2013, so be sure to request it for your house.
The ultimate system will use your electric vehicle or plug in hybrid for electrical storage and backup power.
R. Carter Scott plans to do this, and I'm sure he'll report more about it.

Wednesday, February 13, 2013

LED Lighting Innovation?

110v LED light bulbs each contain some circuitry to make them work with 110 volts AC.
LEDs are happier with 24VDC.  LED bulbs also use just a small fraction of the power of incandescent bulbs. That means that the typical 14 gauge wire going to light fixtures will be overkill for LED lighting, and be a big waste of copper.

So, theoretically, lots of money could be saved in new construction if the lighting power and distribution system could be optimized for LEDs.

Lumencache.com proposes to do just that.  This is a great idea, but boy, high volume means everything to low prices.  Trying to change how new homes are wired will be an epic uphill battle against code officials, old building professionals, and timid homebuyers.

Monday, January 28, 2013

Strategies for Using a Photovoltaic System to Achieve Net Zero

We have designed a 1400 square foot 2 bedroom house to build near Platt Park. The levels of energy efficiency are comparable to Passivhaus standards, but our main goal is net zero energy cost.  The only way to achieve this goal is with renewable energy. A photovoltaic (PV) system is the best choice.

Now, we could make some reasonable assumptions about projected energy usage for the house in order to size the PV system.  In reality, it's impossible to predict the actual usage for a house, so let's look at the whole problem for other clues to size the PV system:

1.  The roof size places a practical limit on the system size based on the actual roof size and how much photovoltaics will physically fit on it.

2.  In new construction, Xcel Energy limits the size of your proposed system based on how much energy they think you will use.  They make a very primitive and arbitrary guesstimate, but the good news is that they will let you oversize the system and pay you more than retail for all the energy you collect and put on the grid. Since Xcel pays you retail price for the energy you generate, they get to say what the maximum size is.

3.  For an existing home, Xcel will let you size the system based on your last 12 month's actual energy usage.  They will let you build it 20% larger than that if you really want to (because you're SURE to get an electric car here in the next two years, and you need the extra capacity).  For most homes, the roof will be nowhere large enough to provide all your energy needs with PV

Xcel used to pay a one-time cash rebate on your system as soon as it was installed.  Nowadays, the rebate system is performance-based. Your contract with Xcel simply obligates them to pay you, as the system owner, $0.13 per kwh generated, up to the contract maximum per year for ten years.  The contract maximum is also the expected annual output of your system.  This strategy protects Xcel because if your system doesn't perform as expected, they don't have to pay.  It also gives you a big incentive to get your system functioning properly.

By entering into a typical power purchase agreement (PPA) with a solar leasing company such as Sun Run, you can get in the game immediately with no cash out of pocket