Project Update: Our NH Eco-Friendly House Plans

By: Kate HambletJuly 9, 2024

There have been A LOT of changes over the past few months regarding our home project.  We were planning to start construction on our forever home this summer, but in early spring, we got derailed by a very high construction cost estimate.  

There were a lot of factors that may have contributed to the super high costs, and I'll get into that a bit later.  

But first, let's talk about what we're going to do now!

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The New Plan:

Getting the very high estimate for our house was pretty crushing.  So I took a few days to sulk before figuring out a new plan.  

We knew from the price we got that we weren't going to be building our forever home this summer.  Even if we got another estimate from a different contractor, or worked with our contractor to figure out where the high costs were and then made some adjustments, we wouldn't have time to do all of that before summer began.  

And unfortunately, we're in a bit of a time crunch because our current living situation isn't great for long term, and inventory is non-existent in our town, so we couldn't find a place to rent or buy in the meantime.  

We've always planned to have a 'barn' on the property to use as a workshop and office space, and we figured that would happen at some point in the future.  But due to the circumstances, we decided to build the barn first and live in it until we decide what to do with our main house.

So we're building a barn!

The Floor Plan:

To make sure the barn works as a home for our family, it needs to have 3 bedrooms, 2 offices, 1.5 bathrooms, a place to workout, an organized mudroom, a functional kitchen, and good natural lighting.  So we're asking a lot from this temporary living space.

And since the final use for the barn will be a workshop and office space, we needed to keep that in mind when designing the floor plan.

Here's what we came up with:

The barn is 2 stories plus an unfinished basement for storage, utilities and laundry.

The total area of the finished space is 1,410 SF. 

The footprint of the barn is 24' wide by 32' long.

First Floor Plan:

The first floor has the mudroom at the main entry, a very small powder room, the kitchen, dining and living rooms, and an office.

I've maximized the windows on the south and east faces of the house and placed the living spaces on those sides. I minimized windows on the north and west sides to keep material costs down and to help with energy efficiency.

We'll heat and cool the first floor with a wall mounted mini-split air source heat pump designed for cold climates.  I'll also have supplementary heat in the mudroom with an electric radiant mat below the tile floor.

The 9' wide south-facing windows are covered with a small roof overhang to keep the sun out of the house in the summertime.  The east facing windows are shaded with a pergola.

In thinking about the future use of the barn, I made the south window openings 9' wide so that eventually the windows can be replaced by an overhead door (when it turns into a workshop).

Second Floor Plan:

The second floor contains the 3 bedrooms, the full bathroom, and the office / workout space.  The bedrooms are small, so we'll need to incorporate some smart storage solutions.

Eventually the bedrooms will become our offices when we build the main house, and the office/workout space will be a hangout space for the kids, so we prioritized putting the bedrooms on the south face so they'd get good sun when the rooms become offices.

We'll have one mini-split for heating/cooling in the office/workout space and one in our bedroom.  The kids will freeze. (Just kidding.  We're going to test out how warm the rooms stay with the mini-split in the hall area, and if it's too chilly then we'll add electric baseboard heat in their rooms.  It'll be wired and ready to go if ever needed.)

Energy Efficiency:

It's very interesting to design a house that will only be a house for a few years.  I had to rethink a lot of my normal energy efficiency design approaches because I didn't want to overbuild for what will soon become a workshop.

With that in mind, we kept the building envelope very simple.  We're doing 2x6 wood stud construction with 5.5" thick TimberHP wood fiber batt insulation in the wall cavity.  The basement will be insulated with 2" of Tremco Warm n Dri fiberglass insulation.  The roof will be insulated at the attic floor with 2 layers of wood fiber batt insulation.  I'm hoping the first layer will be 7.25", but I'm not sure if that will be available from the manufacturer by the time we need it.  The second layer will be 5.5".

It was hard to not beef up the insulation more than this because this is the absolute code-minimum amount of insulation I can put on this house.  But here's why I didn't.

Embodied Carbon:

We (all humans) need to be incredibly careful about how much carbon we're putting into the atmosphere right this moment.  Embodied carbon is the amount of carbon associated with making a product and getting it to its final location. Operational carbon is the amount of carbon a building uses to keep the building running once its been built.

If we want a chance at reducing carbon emissions, we need to be thinking about the embodied carbon side of things first when it comes to building buildings.

Because of this, I'm being very selective about how much material I bring into this project.  

If I were to put 2" of exterior polyiso foam insulation on the outside of the barn to give it a better R-value and remove thermal bridging, I'd be putting a lot more carbon into the atmosphere than if I didn't use it.  And if I were to be living in the barn for the next 30 years, the extra embodied carbon might be worth it because it would keep the operation carbon much lower for the lifetime of the building.

BUT! since I'm only going to be using the barn as a house for a couple years before it turns into a workshop that doesn't need to be super well insulated, the extra insulation on the outside doesn't make much sense.  Basically we'll be doing the planet more harm than good by putting the exterior insulation on the barn.

We could have used a more carbon friendly exterior insulation product like wood fiber insulation, and if we did that, it wouldn't have had as much of a negative impact as the polyiso foam insulation, but again, we just don't need it after a few years.  And right now, the only wood fiber exterior insulation is coming from Europe, so there's a decent amount of embodied carbon associated with transporting the product.  

Air Tightness:

Even though we're not going heavy on the insulation, we are going strong on the air tightness of the barn.

This will be a super air tight enclosure by using the Zip Sheathing system, and carefully taping, sealing and glopping goo onto all openings and joints.  I'll talk about this more in my next post about materials.

Windows:

In an effort to keep costs down and improve energy efficiency, I was strategic about where I placed the windows.

I maximized the windows in the living room and dining room to bring in a lot of wonderful light to our main living areas.  

There's one window in the kitchen to activate cross ventilation in the first floor living spaces.  And there's one window in the first floor office so it doesn't feel like a prison in there (that's my husband's office 🙂 ).

I also put two windows on opposing walls in every bedroom to make sure there is the ability for cross ventilation to help cool the rooms in the summer.  (This is why I love corner bedrooms!)

The west and north faces have very few windows since windows have a lower insulation value than walls.

Dining Room view from kitchen (looking East):

living Room view (Looking South):

Kitchen View (Looking West):

Final Thoughts

So this is the new plan!  We're excited to get started and finally have a place we can call home.

I'm also seeing this house as a bit of an experiment.  I'm curious what the comfort level will be in a modestly insulated home using wood fiber insulation.  This type of insulation can balance temperature swings in a way that fiberglass and other synthetic materials can't, so its ability to control thermal comfort goes beyond the R-value.  I'll talk more about the insulation and other materials we're using in my next post!

I'll be back soon with more information on the materials we'll be using and cost information about the original house we had priced.


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