smell the glory

The Bright Green Future

So about a month ago, I posted a picture of a weird, ugly little house. Kim and I own that house. It is nestled on approximately one acre of land which borders a local park in beautiful Tucker, GA. We are divesting ourselves of our current real estate holdings (the house in Sugar Hill has been sold, and we close on our Athens house in a few weeks), and moving to Tucker. We bought this tiny little house with one thought in mind.

Let’s tear this bitch down and build new one.

And starting in May, that’s exactly what we are going to do. We’re going to build a modern Craftsman style home where this little house currently stands. But, in a somewhat unusual step, we are going to build an extremely energy-efficient home out of non-conventional building materials. I’ve spent literally hundreds of hours researching this topic, and I’m going to talk a little bit about the process right now. If this sort of thing bores you, you can stop reading. If you want to learn a little, just click more.

I’ve been tell The Greatness about this house for months now. Recently, I showed him a preliminary floor plan for our new house, and I think he was slightly surprised because the house is a little bit bigger than he expected for a “green” house. He asked me how this how the house was going to be so energy efficient. This was my reply.

“A ‘green’ house doesn’t have to look any different from a regular house. Or be any smaller (although, obviously the smaller the house, the less energy you will use to heat/cool it).

Here are some of the features that will make this house be incredibly energy-efficient:

We’ll begin by using Insulating Concrete Form (ICF) construction. These are high density styrofoam insulation blocks with concrete poured in the middle. There are about 60-80 different manufacturers of these blocks. We are using a company called Logix. We chose this brand for two reasons - it has the thickest layer of styrofoam insulation of any of the major brands, and the distributor in Atlanta for Logix is one of the most qualified and capable builders of all the ICF people we spoke with.

Because the exterior walls are made of concrete, ICF buildings are fire-rated for 3 and 4 hours, instead of 15 minutes. Also, because of the strength of the concrete walls, they are far better protection against hurricanes and tornadoes. ICF is becoming very popular in Florida for this reason. Every house in New Orleans that was rebuilt after Katrina should have been built using this technology. Because ICF has these benefits over traditional stick-built homes, all of the major insurance companies offer a significant home owner’s insurance discount for ICF homes.

Since the exterior walls of the house are concrete, termites are far less of a problem as well.

The major ICF energy benefits are related to the building thermal envelope. ICF construction does a much better job of maintaining temperature than standard stick-built construction. It has an exterior wall R-value of between R40 and R50, which is more than double stick-built construction with standard insulation batts. Plus air leakage is a problem with batts and stick-built construction. ICF basically eliminates air leakage.

An ICF house of the same size as a regular stick-built house needs a smaller HVAC unit. If you put the same size HVAC unit in an ICF house that you would in a regular house, it will cycle on and off too much and actually increase your energy spending. So you can downsize the HVAC unit, saving money, and then you will have a more efficient house on top of that.

In addtion, because ICF houses are basically air-tight, you have to have to have an air exchanger to avoid sick house syndrome. To really help maintain our energy-efficiency, we will use a Heat Recovery Ventilator which will transfer up to 85% of the heat from the outgoing air to the incoming air, thereby saving much of the ongoing cost of reheating the new air.

Because the roof is still made of traditional wood roof trusses, you have to do something slightly different in the attic. Instead of blowing in fiberglass insulation on the floor joists, you use a open-cell spray foam insulation such as Icynene on the underside of the roof. This type of insulation is about 3 times more costly than standard insulation (hence, we are only using it on the roof), but it is the most effective way of insulating traditional stick-built structures. You could use it on a traditional stick built house to dramatically
improve the energy efficiency, but it still won’t match the high values of ICF and it’s so costly that if you are building from scratch, you might as well do it with ICF to begin with. For retrofitting older homes, however, this is a great technology.

We talked about using underfloor radiant heat as well. Instead of a traditional heat pump or furnace, you place water tubes in the floor that run continually heated water through them. The heat from the water radiates throughout the house. It is much cheaper to heat a home this way, and there is the added benefit that you are not forcing air around like a convection system, which minimizes allergy and sinus problems related to dust. Unfortunately, the start up costs are very high and you still have to have an air conditioner (particularly here in Georgia), so you still end up paying for the A/C andductwork, on top of the cost of running tubes, plus purchasing a boiler (a small, wall-mounted model, not a gigantic creature living in the basement with Freddy Kreuger) for heating the water. This is probably going to end up being cost-prohibitive for Kim and I, but we’re not closing the door on it just yet.

And of course, our potable water will be heated by tankless water heaters. Instead of having a big tank that is keeping many gallons of water hot constantly for when you might need it, tankless heaters turn on automatically and start heating the water when water flow begins. We will be using several small models at the point-of-use to minimize the loss of water due to travel time across the house. Every time you turn on the shower and wait for the hot water to kick in, you are wasting water. Point-of-use heaters will allow us to avoid that, plus have the added convenience of almost immediate hot water. It does cost a little more initially, but the multi-year long term benefits are quite worthwhile.

Of course, high quality energy efficient windows and doors are a major part of this equation. We will be using double-pane, argon gas filled windows and insulated exterior doors to ensure the best energy efficiency possible.

Kim and I planning to live in this house for a long freakin’ time. It’s a nice, quiet area with good schools, and it is much closer to downtown Atlanta and city life than our old house in suburban hell. So we’re going to spend a little extra money now on these energy efficiency technologies and ensure that we have a comfortable and affordable home for the long run.