Thursday, October 30, 2008

What Ever Happened to Off-Peak Electric Rates?

In the 1970's, PSCO introduced off peak electric rates, which were designed to flatten their demand profile. At the time, a kwh used between 10pm and 6am was priced at less than a third of the cost of an on-peak kwh. If utilities can just tweak their customers usage habits thru rate schedules, they can really drop their capital costs. That is, they won't have to build that new power plant just to cover three week long spikes in demand.

Over the years, the PUC added many "cost adjustments" to the electric bill, which watered down the off-peak savings to be had. Eventually, all customers lost interest in the whole program and it was cancelled. These cost adjustments are multiplied by the kwh usage, and now account for around 66% of a residential electric bill. It didn't matter if all the usage was off-peak, these adjustments were still there in full. So, in 1980 if you were saving 2/3 of your bill with off-peak rates, by 2008, your savings would be 2/3 of the remaining 34%, or only 22%.

Sunday, October 12, 2008

Finally a Foolproof Toilet Fill Valve to Save Water

We had three brand-new toilets that leaked slightly, apparently through the flapper. Even if it wasn't a significant amount of water, or caused a noticeable increase in the water bill, it caused an unsightly red mold to grow. Even though the toilets are cleaned weekly, the mold can be seen as vertical stripes in the bowl wherever the leak runs down the sides of the bowl.

Anyway, Fluidmaster now makes a new fill valve that refuses to refill if there is a slow leak. As soon as the handle is jiggled, however, it will refill. So a tenant can use it just fine with minimal inconvenience, but the normally wasted water is saved.

This may increase your callbacks in new single family construction, but it's the perfect solution for buildings with maintenance staff.

Tuesday, October 7, 2008

H4H Redefined the State of the Art for Zero Energy Homebuilding

With NREL, Habitat for Humanity has built and tested the simplest Zero Energy home that I've seen to date. Lots to learn from the following final technical report:

Perhaps the most surprising lesson is the poor overall system efficiency of the solar thermal DHW preheat system. It shows that these systems may be hardly worth the effort. Ongoing maintenance for a system like this will further degrade the cost/benefit ratio for this subsystem.

Monday, October 6, 2008

NREL Denver Tour of Solar Homes

On Saturday, our East Wash Park home was on this year's Denver Tour of Solar Homes , sponsored by NREL.
Here's the blurb from the tour book:

Dickson Residence

This large house (4200 square feet) was completed in 2004 and is an updated version of the “Denver Square” design. The parcel was formerly a public service substation on three lots. The house uses a true direct gain passive solar design in that it has south facing glass and mass (concrete floors). Please note that the passive solar heating provides 90% of the space heating requirements – so much so that the radiant floor back up system is rarely used. If the owners were to do this again, they would install a less expensive backup system. In some places the concrete has been stained so that it is the actual floor. In other places, cork is laid over the concrete.

The house is joined to the building next door, which originally contained battery storage for the Denver Tramway system. Now the building houses an office and shop area.

The house is built using SIPs (structural insulated panels). In getting the permits for the house, the Denver plan review and inspection departments added eight months of delay in getting a building permit, according to the owner, because of their inexperience with SIPS. Greenprint Denver may be helping to alleviate the problems like this.

An interesting note is that three of the stained glass windows in the house were designed by a relative of Frank Lloyd Wright.

Passive Solar Features


Mass of 2” of concrete on the floor

Trees planted on the east and west for shade control

Photovoltaic Panels

3.3 kW system

Grid tied

Utility bill has decreased $55 per month since installation

Thermal Envelope / Thermal Comfort

Insulated above code with SIPS

Low-e windows

Interior and exterior shades

Evaporative cooling (unique indoor cooler)

Expanding foam insulation around windows and outlets

Zoned heating

Night setback thermostats

Radiant floor backup heating system


Some CFL lights

Motion sensors or timers in the mudroom and garage


6” thick SIPS walls

Thermal breaks at entry doors and perimeter of entire foundation

Pre-plumbed for solar thermal collectors

Lightweight Metal shingles


Energy Star rated

Sealed combustion boiler/hot water heater

Transportation / Lifestyles

Hybrid SUV

50% of all errands are done by bicycle

Light rail is used once a week



Vegetable gardening

Re-Use / Salvaged Materials / Recycle

Reclaimed brick

Reused existing building and converted into a home office from its original purpose

Unique Features

Homeowner trained in solar during the energy crisis of the 70’s

Homeowner holds patents for pneumatic fittings, valves, and a nose hair trimmer

Green Features

EPS insulation

Stained concrete floors

Reused an entire building and converted into a home office

No particle board was used

Steel roof

Cork floor

Water Features

Low flush toilets (5 out of 5)

Low flow shower heads (3 out of 3)


Drip irrigation

REC’s and Windsource

On demand hot water system: “Doorbells” in each bath summon hot water without wasting it

Sunday, October 5, 2008

A little bit of nice publicity from the WPP....