Using Radiant Floors for Backup Heat

Radiant floor heat is considered by many to be the most comfortable method of delivering heat. Even zero energy homes need a source of backup heating. Therefore, radiant is often the choice in high end custom homes, when cost is trumped by comfort and "sizzle". After building and living in a near zero energy home now for three years, we have learned that radiant heat is quite comfortable when it is on. The trouble is, the solar and superinsulation aspects of the house prevent it from coming on very often. Close attention was paid to the basement insulation details. As a result, the heat loss is so low that the basement zone comes on only about 4 times per heating season. Again, that zone wasn't worth the cost when a couple $30 baseboard heaters could do the job.

Chicago's Demand Management Scheme

I harp about utility demand management a lot. Take a look at what Chicago is doing in this field. With a properly designed system in Chicago, you might never have to pay more than $0.03/kwh. In Denver, you never can get a rate of less than about $0.08.

Technically, it doesn't save any energy or prevent CO2 generation. It does, however, eliminate the necessity of building of new, larger power plants. Reducing utility capital expenditures should help keep electric costs down.

In fact, it's the first on the list of sustainability priorities that electric utilities must pursue, listed here in order of best cost/benefit:

1. Peak load shaving (with nighttime load valley filling).
2. Conservation.
3. Bringing renewable energy sources on line.

Sustainability and Maintainability

Sustainable Housing can be defined as housing that conserves resources as much as possible.

What's the most important resource to the average person? Their MONEY. Therefore, new green built homes should not only aim for zero energy, but also for zero maintenance. Life's too short to paint siding.

Here's the start of my zero maintenance checklist:

1. No exposed, painted wood. Board and Batten wood siding may be used if you make the pledge to let it weather naturally, and turn silver grey, then mottled dark brown.

2. Use large gutters and downspouts. The bigger they are, the less likely they are to clog. Employ scuppers where appropriate, they can be cleaned in a fraction of the time. Pop rivets should be specified in lieu of screws. "Gutter Helmet" type devices are not the silver bullet, but they can help.

3. Consider designing the house to look good with galvanized sheet metal trim. 24 gauge galvanized gutters and fascia will never have to be replaced or even painted in your lifetime. When it does start to rust in 80 years, let it, and go for a rustic look. Failure is still 40 more years out. Of course, copper is even better, but the price/performance is not.

4. Pay a lot of attention to the "splash zone" where rain puts wet mud on the house on the lowest 12"-36"

5. Low maintenance landscaping. Please don't be tempted to put concrete and asphalt everywhere, or astroturf.

6. Fiberglass windows. These really are the only option for zero maintenance windows. Vinyl will crack eventually, and any sort of wood window needs regular painting or varnishing.

Attic Design Update

The gurus at Building Science have updated their conditioned attic recommendations for every climate. If there is one code requirement that should be implemented immediately, this is it.

And for those roofers and shingle salesmen who always say "It will void the shingle warranty", attic ventilation has very little effect on shingle temperature.

Conditioned attics are now finally allowed in the IRC building code, which Denver uses, but they should be mandatory. They can be accomplished at little to no cost, because they eliminate the often tricky attic ventilation requirements.

The simplest steps to a better wall.

Two easy changes can be made to conventional wall building:

1. Start by framing on 24" centers:
Optimum Value Engineering
It's hard to get experienced framers to change their ways, but this saves a lot of wood with some extra design time. You have to give them a drawing that shows every stud and header location and configuration.

2. Thermal bridging is a big issue in stud walls. Dow Styrofoam helps at almost no extra cost. Note that it eliminates most of the (rot prone) OSB in the structure, and if you tape the joints, it eliminates all the Tyvek. "Styrofoam insulating sheathing" keeps most of the water at least 1/2" away from all the wood in the house. Nice.

Demand Management

There has been quite a lot of controversy surrounding the proposed new Xcel towers at Ruby Hill. Does anyone realize this upgrade can be completely avoided with prudent Demand Side Management?

This from the Leonardo Energy website:
"Italy is currently undertaking a programme to install 30 million smart meters. It is estimated that demand-side management tariffs, which limit customers to 3KW of power during peak periods, have reduced peak demand by 5% for 3 hours, 10 days a year. This has removed the need to construct a power station with 2GW capacity to cover the peak demand."

Smart meter technology can also prevent all new powerline capacity upgrades.

Passive Solar Heating is Simple

I found this European, scholarly, technical paper on Green Building.

Here's my favorite passage:

"3.1 Heating
3.1.1 Passive systems
General considerations The best way to reduce energy consumption is to take advantage of all available natural energy. This is the purpose of bioclimatic design, which is one path to a low energy house. The bioclimatic approach operates at two levels:
1. let the energy of the sun come in
2. do not let it out again"

It really doesn't get much more complicated than that. We've been in our near-zero energy home for 2.5 years now, and have discovered that not only are we saving energy and money, the comfort is amazing.

A relatively overlooked aspect of passive solar is that you want windows with high SHGC (solar heat gain coefficient) on the south side, preferably with overhangs. In the actual marketplace, I have as yet only found only one supplier of these windows, Hurd. Be sure to specify "hard coat" Lo E. In addition, don't "overglaze" the south side, you might get October overheating or need to wear sunglasses indoors.

Now, armed with that advice, find a building site where your neighbor can't block your sun.