“It Aint Easy Being Green” - Kermit the Frog

Heather Keith wants a Green Built House. She wants her house to be easy on the environment in both its construction and use. The question: are green materials and practices really green?

Heather's Architect, Melissa Kyer of SunQuest Architecture, chose materials based on the environmental impact , recycled content , sustainability and embodied energy of the material. “Embodied energy is a term used to describe the amount of energy that is used to make the product” said Ms. Kyer. “the less energy used to make a product, and getting it locally, reduces a materials embodied energy. As for recycled content, we looked for products that contain a high percentage of post consumer waste.”

For example, if you cut down all the rain forests just to make a single 2x4 then the embodied energy in that 2x4 is very high. Conversely if you can build an entire city block out of the energy contained in say, a chocolate doughnut, then the embodied energy is very low.

The long term goal of building “Green” is to get the most building for the least amount of environmental impact, so low embodied energy is good.

Before we begin, lets increase our vocabulary:

“Embodied energy is the energy consumed by all of the processes associated with the production of a building, from the acquisition of natural resources to product delivery, including mining, manufacturing of materials and equipment, transport and administrative functions” This according to CSIRO

Form - as anyone who’s ever carved their name in a wet sidewalk can attest, a concrete form can be as simple as a few scraps of lumber filled with wet “mud”

Mud - slang for concrete, which is often a mixture of Portland Cement, water and rocks of different sizes

Concrete - again, often a mixture of Portland Cement, water and rocks of different sizes

Insulated - like your coffee mug, insulation keeps the cold out or the hot in.

Pour - like filling a cake pan with batter, it’s the act of filling the forms with mud

Blowing out - like a water balloon hitting the pavement, the weight of the mud in the forms can cause the form to split open

Since most every house sits on a foundation that’s where we’ll start our story.

There are a few different kinds of foundations but were going to stick to poured concrete and Insulated Concrete Forms (ICF’s).

Traditional poured concrete is really just concrete poured into a big plywood form, when the concrete is dry the forms are pulled and the result is a free standing concrete structure. More often than not, this is what houses are built upon.

If you’ve ever been in an unfinished basement you know, the walls can get cold in the winter. To warm the basement spaces the walls need to be insulated and finished. The materials and labor to finish these spaces adds to the cost of the basement and may raise it’s embodied energy.

In an ICF foundation the forms that hold the concrete are made from an insulating material. An ICF is usually a single block made from a polystyrene type foam, or in more green products, a recycled and or renewable mix of materials. The ICF blocks are stacked up like Legos (brand toy blocks), braced with wood structures and the concrete is pumped into them. Instead of removing the forms like the traditional method, these forms are left in place to insulate the concrete from inside and outside. Several of these ICF systems make the task of finishing the basement easier and less expensive.

Remember, the less energy that’s used to produce the finished product the better. Many ICF foundation systems claim to have low embodied energy, but that’s only half of the story. Manufacturing the blocks is only part of the finished product - which is a foundation.

In traditional foundation pours the forms are set by a group of people who do not need a general knowledge of carpentry, their specialized knowledge of forms allows them to set up the forms in a day or two, depending on the size of the house.

Traditional forms can be filled with mud from a pumper truck fairly fast, meaning the truck that pumps the concrete and the trucks that deliver the concrete spend less time sitting in the street running. Concrete professionals have been using this system for a long time and all the bugs have been worked out. After the mud dries the forms are pulled and taken to the next job where they will be reused. In fact, concrete forms endure a great many pours before they are retired.

So, to summarize a traditional pour there are:
Three or four people erecting the forms
Three days of driving to the job
Sixteen hours of building forms
Two or three hours of pouring
Four or five hours taking the forms down

The waste from a job like this is a few scraps of lumber and a bunch of bits of tying wire.

To build a foundation using ICF’s requires the specialized skills of a carpenter, a brick mason or a tradesman with the knowledge required to use the brand of forms selected. The blocks are stacked in rows, which takes longer than setting traditional forms. Each block is attached to the blocks around it with special fasteners, glue or both. As the wall is going up the blocks need to be braced. If the blocks are foam they need to be protected from the wind. There have been cases where an entire foam system was blown apart by the wind.

The bracing used to hold the ICF’s is usually cut for a specific purpose and when it’s not being used any longer it becomes waste. ICF’s have a reputation for blowing out so the people who work with them go to great lengths to prevent it. The end result is they use a lot of lumber and plywood to brace everything that might go wrong, and they keep extra lumber on hand to shore up soft spots.

Chris, the pump truck driver on a recent pour, said it takes about twice as long to pour an ICF foundation than it does to pour a traditional one. The mud is pumped in more slowly because of the potential for a blow out, hence the pump truck and the mixing trucks sit on the street running longer. (by the way, pumper trucks are controlled with a wireless remote making them just about the biggest R/C toy in the world!)

Once the concrete sets up the bracing used to keep the ICF’s in place is removed and it’s done. The foundation is insulated both inside and out, and with many systems it’s ready to have drywall screwed right to the ICF. Add some electrical outlets, a little heat and move right in.

Let’s summarize an ICF pour:
It takes three to ten people about a week to build an ICF foundation. (complicated foundations can take several weeks to build, poly-foam foundations take less people and time because the blocks are lighter) Let’s say that averages 7.5 people driving to work five times.
It takes a truckload of lumber and plywood to brace an ICF foundation, and most of that is scrap afterwards, so add in the cost to recycle the lumber.
The pumping and mixing trucks spend twice as much time on site consuming fuel and filling the air with diesel fumes.
To be certain there are enough ICF blocks to build the foundation, builders order extra block to cover the ones that break during shipping and handling. The leftover blocks, some of which are broken, end up as trash.

Some ICF systems make their blocks out of materials that are hard to cut, so it’s harder on the tools that are used to run electrical and plumbing. This might result in a slightly higher cost to run these systems on the part of the electrical and plumbing trades.

All-in-all it’s hard to say if ICF’s have lower embodied energy at the point where the foundation is finished, or if traditional forming methods use fewer resources. Some observers have likened a concrete pour to a circus, if so, then an ICF pour is a-kin to a three ring circus.

To be fair we should remember that the traditional method is just that, traditional. Concrete professionals have been working with that system for a long time and have squeezed out most of the inefficiencies. ICF’s are new, and builders are just now beginning to work out the bugs. Once they have as much experience with ICF’s as they do with traditional methods we’ll begin to see a real payoff in embodied energy savings.

Like Kermit said, “It aint easy being green” but that’s where the building industry needs to be going. There are people in the building trades who have put a lot on the line to bring environmentally friendly materials to market. Some of these cutting edge products are so new it’s hard to find a builder who has experience with them.

If you’re interested in building with these new energy efficient products you’ll need to ask around to find Architects, builders and suppliers who have the special trade skills to use them.

If you’re going to build a truly green house you have to look at all the options that are on the market and choose the systems that will work together. To measure the impact of a house on the environment by just watching the foundation being poured is like judging a person by their first baby steps.

Well built houses last for hundreds of years, and if they are made from energy efficient, recycle building products, their embodied energy at the end of their usefulness will be a lot less. We will all benefit from “green building” in the long run.