A NEW KIND OF CONSTRUCTION
As part 2 of our 3-part profile of the Wheeler residence, we are breaking down the building practices that helped this home achieve maximum durability and a 50% reduction of energy consumption. As Mr. Wheeler put it, “Our aim has been to deliver a building that substantially outperforms the status quo.” That means doing things differently. This is Part II – A New Kind of Construction.
To Begin With
... what does “doing things differently” really mean? Well, it means that everyone involved with building this home made decisions based on a different set of priorities. Like eliminating air infiltration and reducing energy transfer.
THE ROLE OF BUILDING SCIENCE
To build a high performance house, we’ve based our decisions on the principles of building science. For instance, today’s green building movement has utilized natural science and structural engineering to develop new methods for eliminating energy loss as well as controlling moisture. We apply that knowledge to framing walls, choosing materials and integrating systems. We call it a Whole Systems Approach. In a nutshell, here’s how it works:
• Controlling Moisture: Temperature differential causes condensation, which leads to mold, rot and bugs. So we move temperature differential to the exterior of the home where condensation can’t do any damage.
• Eliminating Energy Transfer: Energy is transferred through a home in one of three ways - conduction, radiation and convection. Using sustainable building practices, we've built the Wheeler residence to resist all three.
SO LET'S TAKE A CLOSER LOOK
… and zero in on 2 primary benefits of using a Whole Systems Approach – energy efficiency and home longevity. Then we’ll look at what we learned from this home’s construction.
Energy Efficiency
{a behind the scenes look}
Energy efficiency is more than new appliances, windows and weather stripping. Energy efficiency means using eco-smart building techniques that you can’t always see. Like inside walls where framing and insulation collaborate to stop energy loss. So let’s go behind the scenes to see what makes the Wheeler residence energy efficient.
DOUBLING THERMAL CAPACITY
Advanced Framing: Framing with 2x6 studs on 24” centers allows us to reduce the amount of lumber in walls by 50%. In place of unnecessary lumber, we use insulation to help double the wall’s thermal capacity. And because lumber acts as a thermal bridge by which energy is transferred from one side of the wall to the other, we have reduced thermal bridging and made necessary lumber (2x6 instead of 2x4) a better insulator.
Insulated space: To optimize the home’s thermal capacity, we used insulation to the furthest outer edge of the building envelope. That means we used a rigid foam exterior sheathing, insulated the attic roof and even insulated the home’s concrete slab. From the ground up, the home’s shell acts as a single thermal barrier.
FROM THE INSIDE OUT
Continuous air barrier: To eliminate energy loss, we glued the home’s exterior sheathing to its framing, preventing air infiltration and any resulting condensation. On the home's interior, we used a continuous drywall application to eliminate seams at intersecting walls. And we used spray foam insulation around electrical wiring, ducts and joints at the roof decking to seal all points of penetration.
PREVENT 99%
Radiant barrier: Radiant heat gain is one of the main reasons why our homes heat up during the summer. So we’ve used a sheathing product under the roof that has an aluminum facing which blocks 99% of all radiant heat. Rather than the space underneath the roof getting warmer as the sun bears down on it, the radiant barrier reflects heat so that the temperature differential is moved to the outermost point of the home, and unwanted energy gain is circumvented.
OVERVIEW
Building science teaches us how energy interacts with materials and behaves in different environments. So we apply that knowledge to framing walls, choosing materials and integrating systems. We not only aim to eliminate energy loss, but also build a highly durable and enduring home. read on.
Home Longevity
{& killer craftsmanship}
Think about this – By the time a home is 50 years old, it’s been virtually rebuilt. In other words, it’s common for a home's roof, siding, windows, doors, and HVAC to be replaced and its kitchen and bathroom remodeled at least once over the course of its lifetime. Our aim is for the Wheeler residence to resist obsolescence and last 100 years without being rebuilt. Here's how:
STRONGER WALLS
Metal Strapping & Brackets: As part of Advanced Framing techniques, we utilized metal strapping on the walls in a diagonal crisscross pattern that resists lateral movement and helps reinforce the home’s structural integrity.
Continuous Drywall: We eliminated seams in the interior sheathing by employing a continuous drywall application. In other words, there are no breaks in the drywall where interior walls intersect exterior walls. This not only prevents air penetration, but also serves as a structural component.
Rain Screen: Where the advanced framing and continuous drywall stops airflow, our rain screen siding system prevents moisture from doing any damage inside walls. That is, between the home’s framing and its exterior sheathing, we wrap the home in a high-density polyethylene material that creates a passageway for water to dry or exit from behind the siding without causing mold, rot or bugs inside the walls or around windows and doors.
SOLID FOUNDATION
Insulated Concrete Slab: The concrete slab foundation and floor system is highly durable and energy efficient. Because the slab edge is insulated, there is no opportunity for energy loss, temperature differential and the resulting mold, rot and bug problems that are prevalent in crawl spaces in the Southeast.
ROOF & CLADDING
Standing Seam Metal Roof: The standing seam metal roof has a 30 year warranty. And because of its single pitch design and no intersections or valleys, the roof is designed to withstand harsh conditions over the long term without the need for maintenance and repair.
Cladding: An exterior mix of Hardie and brick cladding provide greater longevity. Hardie siding is a fiber-cement product made with recycled content (wood pulp, cement, sand and water) and resists moisture damage, insects and fire. The Boral Brick product has a twenty year warranty and incorporates a protective pastel coating.
OVERVIEW
Craftsmanship means more than aesthetics and fine-tuned finishes – it is also means paying attention to the details of everything from behind walls to under the house, preventing moisture damage, stopping air penetration and increasing material life-span. So what have we taken away from the construction of this home? read on.
What We Learned
{no means no}
We learned to say “no” to the old way of doing things and deliver a building that substantially outperforms the status quo. In fact, the whole project team collaborated to build a home that stops energy loss, air infiltration and moisture. So what difference does it make?
• Fact: 46% of an average home’s energy costs are the result of heating and cooling. Not the Wheeler residence.
A Whole Systems Approach reduces those costs by doubling the home’s thermal capacity, eliminating air leakage and stopping radiant heat gain – strategies that also help double the home’s lifespan.
• Fact: The average home has the equivalent of an 864 to 1,440 square inch opening to the outside through penetrations in the wall and around fixtures, wiring and ducts. Not the Wheeler residence.
A continuous drywall application and sealed air barrier helped the Wheeler residence achieve a mere 50 square inches of openings.
• Fact: The average home's wall units have an estimated R-value (thermal capacity) around 11. Not the Wheeler residence.
Our advanced framing techniques helped the Wheeler residence achieve an R-value upwards of 21.
So while the Wheeler residence does not employ any new green or energy generating technology, its design and construction has resulted in a 50% – 75% reduction of energy costs.
