The Rubber is Starting to Meet the Road for Smart Grid City

The Smart Grid pilot project in Boulder is now well enough along for the peak period re-pricing to be released.

http://www.dailycamera.com/schoolchoice/ci_13732272

This article missed answering an obvious question:

If you own a PV system that contributes to the grid during peak periods, will Xcel credit you at the higher peak retail rate?

My guess is yes. It's only fair. But this issue should be openly addressed soon because it will make your PV system pay off much quicker

LED Lighting Update

Yes, CFL's suck.

So, we've been waiting for bright, affordable LED lighting to become available. Sam's Club has recently introduced 1.5W LED bulbs for $5 each. I believe Xcel energy is subsidizing some of this cost based on a flyer displayed in the aisle. If anyone knows more about that, please post a comment.

Anyway, 1.5W is only producing about 78 lumens, which means you'll need roughly six times the number of bulbs more than "normal". This is a daunting problem that will keep most folks out of the LED replacement business until a market solution or even brighter bulbs are introduced.

In the meantime, we developed a hack using "Medusa" floorlamps, which can be found for as little as $20 and will convert a standard octagon ceiling box into a fixture with five medium base openings. An added bonus is that you can direct the lighting to where you need it.

Let's say you have rentals or are doing fix and flips. You already know that fluorescent lighting and CFL conversions do NOT add value, even though operational cost is lower. The light quality of LED's and even lower operational costs SHOULD add value to your project. Don't be cheap - the $20 marginal cost per fixture is only a couple hundred $ for a house.

Dual Flush Toilets Now Affordable

If you've been too cheap (like me) to get a Toto or Caroma Dual Flush Toilet, now you have no more excuses. For a long time, these toilets have averaged $400, making them difficult to pay for themselves.

Sam's Club is stocking the Alexis HET (high efficiency toilet) 1.1 gpf liquid, 1.6 gpf solid dual flush toilet for $99.

Since Denver Water is giving a $125 rebate for them, this is a real no-brainer.

Go get one while they still have 'em.

Solar Shading Cont'd

The classic all-aluminum rollup design is my personal favorite solution for exterior window shades. They're economical, ( $150-$300), self-storing, accessible from inside the home, and infinitely adjustable depending on the season or your whims.

They can be ordered at Home Depot or online at http://www.screen-house.com/awnings_rollup_aluminum.htm

Sun Control - One of the Solutions to Summertime Overheating

This topic is old news for those of you with those big, west-facing-mountain-view windows. They create an inferno for you in the summer. You may have even spent thousands on beautiful floor to ceiling blinds to shut out the sun.

However, unless the shades are physically outside the window, they are relatively ineffective. Once the sunshine comes in the window, it stays inside as heat.

So the shades must be on the outside.

The easiest, quickest, and least expensive way to install an exterior window shade without completely ruining the view just might be from Screenmobile. They are a national franchise, and I've used the local branch often for conventional screen replacement, and found them to be a good solution for an annoying problem.

Heat Pump Hot Water Heater

So, you're trying to decide how to heat the domestic hot water in the zero energy house you are designing for Denver.

Solar hot water heaters are an excellent choice. However, the logistics of a solar thermal installation are daunting compared to a typical appliance installation.

A logistically easier solution is to use a heat pump water heater (HPWH) in conjunction with PV solar.

Rheem has just released a new nice-looking unit.

The jury is still out as to which configuration will be best. Recent test results and common sense are beginning to favor HPWH with PV. The reasons for this are that solar DHW is insufficient and inefficient in the winter, and underutilized in the summer. A grid-tied PV system has the advantage of constant efficiency and 100% utilization year round. In addition, large PV cost reductions are coming, but none are expected in solar thermal. State-of-the-art solar thermal collectors still use supply-restricted copper, aluminum, and glass. The labor content of solar thermal installations is also quite high.

Some puzzles remain with the implementation of HPWH systems. Per the manufacturer's recommendations: "Because the heat pump’s exhaust air is cooler than the surrounding atmosphere, these water heaters generally do not belong in or near busy living areas of the home." Since they pull the heat out of the surrounding air, a small, airtight mechanical room isn't the best place for it either.

Discussion of HPWH locations:

1. The garage. A new, well insulated garage might work. An uninsulated garage slab gives off enough low temperature free geothermal heat* to prevent freezing of the pipes to the heater. There are at least two problems with the garage, however: 1. In summer, the HPWH gives off cold air that would be more desirable inside the living space than in the garage. Ducting air from the garage to the house is a CO hazard, and not recommended. 2. If the (insulated) garage door is inadvertently left open in the winter for an extended period, the water lines to the HPWH are at risk of freezing.

2. Mechanical room with forced ventilation. The control scheme and ducting layout for this ventilation can get complicated and costly.

3. Basement. This is where you usually find the water heater in new construction, and will work just fine if you don't mind a cold basement in the winter. If you finish the basement and add heat to it, that heating system will be feeding the HPWH the heat it needs, and this will spoil the overall efficiency of your system.

"The House as a System" philosophy of home design will get a real workout on this one. Please enter a comment if you've heard of any other solutions.

*A perimeter insulated slab in an insulated garage gives off 5-15 Btu/hr/ft2, based on preliminary research. This is a great match for a 7000 btuh HPWH.

The Greenest Building is Usually the One Already Built, but Not Always

I'm really not trying to anger preservationists or tree-huggers here, I'm just analyzing a trite slogan from an engineering perspective. I'm a pragmatic preservationist.

The question is whether or not you should rehab and do a green retrofit on an existing building or replace it with a well-designed low energy new building. The correct answer can only be found after making some reasonable assumptions, cost estimates, and estimates of resale value.

You don't "waste btu's" when you tear down an old building. Those btu's were spent when the building was originally built, and there's nothing you can do to get 'em back.

You can only choose not to spend new btu's on a new building.

And btu's are just another form of dollars.

So it's always an economic problem, eg., what's the present value of retrofitting the old building vs. building an entirely new one. This analysis must be done for every building using each case's unique problems and assumptions.

In residential at least, it's fairly easy to build a new "zero energy" replacement house, but fairly hard to retrofit an old house to zero energy. The cost of the new house can be estimated pretty accurately, but trying to estimate the retrofit cost of the old house is risky. Every old building is different.

The embodied energy of the new building is just part of the down payment on a really good investment. The value of that energy is in the cost of construction. The landfill space required for the old building is also given a dollar value in the cost of demolition. The embodied energy of the old building is a "sunk cost" and doesn't factor in the analysis.

The main thing that doesn't have a dollar value in this analysis is the generation of CO2. Lawmakers have begun trying to put a dollar value on that. Eventually this "carbon tax" will be pretty accurate, and will favor the old building.

Most estimates put the embodied energy of a new building at 5-15% of the lifetime energy usage of the building. That means the operating energy usage of the building is about ten times more important than the original energy content.

Therefore, it may be a catchy phrase, but it's very unscientific to generalize: "The Greenest Building is the One Already Built". Be sure to say "usually".