Presentation of Research Project

Please join Confluence Architecture, Habitat for Humanity and the Community Office for Resource Efficiency (CORE)

5:30pm – 7:00pm Tuesday, January 27th, 2015 at the Third Street Center, Carbondale, Colorado for a presentation of a research project titled

“Dollars and Carbon: Effectiveness of Sustainable Construction Methods in the Roaring Fork Valley of Colorado.”


Confluence Architecture and Habitat for Humanity received a “Design Assistance Grant” from CORE to research the life-cycle and return on investment of energy efficiency construction upgrades to single-family homes in the Roaring Fork Valley climate.

Discover the most effective strategies for constructing affordable homes in the Roaring Fork Valley to minimize lifetime utility costs and carbon emissions.

Download paper here: (warning it is about 7 MB)   The Effectiveness of Sustainable Construction Methods


Confluence design – Marble Distilling Company – makes local news

We are excited to be overseeing the construction of the Marble Distilling Company, in Carbondale, CO.  (co-designed with Project Architect, Energy and Sustainable Design).  This great project just received some local press. Check out the story at Aspen Public Radio and Carbondale Chamber of Commerce. Check out the interior renderings by Confluence Architecture.

Hotel room

Tasting Room


Confluence Architecture goes Net-zero (electrically)

This week Confluence Architecture had a 3.24 Kw photovoltaic solar system installed on the roof to offset the electrical consumption of our firm. Our building already sports passive solar heating & a thermal solar hot water system. The addition of these twelve solar panels drops our HERS rating to a very healthy 30. We felt like the time was right to take the plunge because the cost of solar systems has been dropping and incentives are still high. The system will cost us $14,000 out of pocket, but by the time we collect the incentives and take the federal tax credit it will be more like $5,800! If electric costs were to stay at current rates- we could see this system pay for itself in savings in just 10 years. The system is slightly oversized, because our business plan calls for a plug-in electric vehicle as the next step towards carbon footprint reduction. Our inverter can take another string of panels if we find that more would be beneficial. Many thanks go out to the folks at SoL Energy for a first-rate installation job; Ken Olsen, Kelly Kirby, Mike Bouchet and Nirish Kafle.

solar PV installersPV inverterPV-array

Marble Distilling Company

Architectural Renderings

I’m a bit of computer geek and certainly an energy geek. Did you know that the harder you work your computer, the more power it consumes? The one thing that really pushes my computer is architectural rendering software. The computer has to do complex calculations to trace the path of light in a simulated three dimensional space as it bounces around. Every material has its own attributes; shiny, transparent, translucent, etc. Then there is shade and shadow, natural and artificial light to consider. The software goes through a dozen or more layers of calculation for every pixel of an image.
Recently we were retained to produce three images for the Marble Distilling Company. Once a model is set up to be rendered, it can take several hours for the computer to crank through the calculation process. In one case, the computer was working so hard, the power supply actually burnt up! Pop, smoke and dead computer.

dead power supply

The Mable Distilling Company of Carbondale, Colorado is set to open in February. Until then, here is a peak at the interiors and a link to their website.


Distillery tasting room

Hotel bathroom

Hotel room

Effectiveness of Sustainable Construction Techniques in the Roaring Fork Valley

CORE grant awarded for research project

Confluence Architecture and Evaluation Services, LLC in collaboration with Habitat for Humanity Roaring Fork Valley received a grant from CORE (Community Office for Resource Efficiency) to conduct research to better understand the life cycle and return on investment of several energy efficiency construction upgrades to single-family homes in the Roaring Fork Valley climate. The grant funded a study that compares various energy efficiency construction components by their ratio of installation cost to KWH of energy saved and tons of carbon saved. After a year of work, we are happy to share the results here:

Executive Summary

This study seeks to answer a subjective question: How best can additional money and carbon be invested in the construction of an affordable home in the Roaring Fork Valley to minimize lifetime utility and carbon costs?

This question is investigated through the lens of a Habitat for Humanity home currently under construction in Carbondale, Colorado. While not changing the physical design of the home (shape, footprint, floor plan, windows, area etc.) 100+ home configurations are studied through LCA (life cycle analysis), energy modeling and construction cost estimates. The configurations focus on practical construction choices made every day such as wall assemblies, insulation levels, treatment of crawl spaces, attics and mechanical systems.

The study finds, unsurprisingly, that the most expensive home configuration to build saves the most carbon and has the lowest annual energy costs. The perfect mix between initial construction costs and carbon and energy savings is dependent on the values of the investor. In order to illustrate several successful investments, this report contains an in-depth analysis of 8 benchmark home configurations that illustrate practical construction combinations over a range of investment and performance levels. Following is a list of notable trends distilled from the data:

  1. The best way to reduce the carbon footprint of a home is to reduce operational energy consumption, even if it raises the initial construction carbon footprint. The carbon footprint for materials, transportation, and construction of the home is exceeded by the carbon footprint of the annual energy usage in three years for a typical code home and five years for a high performing home. Construction carbon becomes important only as homes begin to reach net-zero and in some key carbon-rich construction materials.
  2. The largest factor in fuel consumption and construction cost is the mechanical system. Avoid electric heating of any kind. Ducted furnace air systems are the lowest monetary cost path to efficient building heat. Hydronic systems provide the best comfort and have an overall lower carbon footprint- with an added monetary investment.
  3. Avoid active cooling. While air-conditioning use is increasing in the Roaring Fork Valley, energy modeling reveals it to be unnecessary for a well-designed and built home in our heating dominated climate. The cooling load is only 3% of the heating needed. Active cooling systems have the potential to use excessive electricity in an area where there is little need, especially if it is used in lieu of passive strategies (like appropriate clothing, opening windows at night, and proper shading of glazing).
  4. Insulation continues to be a cost effective way to increase building performance. The type and location of insulation matter. This study found continuous exterior insulation to be more effective than added cavity insulation. SPF (Spray Polyurethane Foam) insulation proved not to be as cost effective as other insulation types, going against an emerging trend for SPF in the Roaring Fork Valley. Beyond the cost and performance balance, insulation has the single largest impact on initial material carbon of any building component. The carbon footprint of like performing insulations types can vary 500-fold. The lowest carbon insulation option is blown cellulose while carbon intensive insulations are XPS (Extruded Polystyrene) and SPF.
  5. Air Sealing is on par with insulation in its cost effectiveness in increasing building performance. If careful air barrier control becomes a part of standard construction techniques the energy savings reward is significant relative to cost.
  6. Volume is a luxury. Two homes that are identical on the exterior and have the same mechanical systems, windows, and shell construction can vary in energy performance by 5 – 15% due to the inclusion of vaulted interior spaces and conditioned crawl spaces. It is notable that this is one of the few areas where carbon and money are not at odds. More compact interior spaces are cheaper to build, require less initial construction carbon and are more efficient to run.
  7. Photovoltaics are becoming a key component to include in any home shell beyond the basic code minimum. This came as a surprise to the study authors, questioning a rule of thumb where shell upgrades are better done prior to the addition of renewables. Due to continued price declines, PV is proving to be more economical than many shell upgrades such as high performing windows or super insulation.
  8. Net-zero is not out of reach. This study finds several home configurations that can be made net-zero in a construction price range ($200-225/sf) that is in keeping with market rate construction and home sales costs in the Roaring Fork Valley. These homes use typical construction techniques and materials.

Download paper here: (warning it is about 7 MB)   The Effectiveness of Sustainable Construction Methods

Stay posted for a public presentation of the results in January 2015.

Habitat for Humanity house earns LEED Platinum!


Confluence is proud to have provided energy and sustainability consultation services for Habitat for Humanity in the effort to provide the Lavender’s with a home with very small monthly utility bills. Below is a TV news and a newspaper story about the Lavender home.



Creative Repurposing

As Confluence Architecture becomes more and more digital, we have less need to keep file cabinets full of paper documents. I imagine this is true for many homes and businesses. So what becomes of all those unneeded file cabinets? They are typically 100% recyclable, which is good. But Angela had a great idea to convert a couple into storage benches for landscaping equipment.

repurposing file cabinet closed  repurposing file cabinet open

HERS rating nets refund

Soffer HERSA home in Eagle County just received its final HERS rating and received an amazing score of 18.  This score resulted in a refund of 25% of the permit fees paid to Eagle County.  This netted the owner close to $5000 refund.  The refund far exceeds the cost for Confluence Architecture to perform the HERS rating.

Stay tuned, Confluence Architecture is also providing LEED consulting on this home.  The final package for LEED for Homes will be submitted to week.  We are on track for LEED gold.


Summer Construction Round Up

This first day of fall is a great opportunity to celebrate what Confluence Architecture has been working on Spring and Summer of 2014.  We currently have 3 projects under construction with a 4th to break ground withing a month.  We are happy to  again be working with Jeff Dickinson and Energy and Sustainable Design on the architectural design of the Marble Distilling Co.  This distillery, hotel and lounge located on Main Street in Carbondale Colorado is finishing out framing.  This fast track project has been exciting.  Look for it to open early 2015.  Be sure to check out Marble Distilling Company’s website and facebook pages to see the evolution of this new venture.

Marble Distilling Company










View of Tasting Room









In addition, three residential projects have been keeping us hopping.  A modern remodel in Aspen glen, an addition on Missouri Heights, and a new spec home on Four Mile Road near Sunlight Ski Area are all under construction.  Keep tuned here for photo as these projects progress.

Blower Door Test

What does it mean for the Builder?

What is a Blower Door Test? It is also called an air-leakage or infiltration test. It measures the air that moves through a building envelope at a standard pressure difference.

Blower Door Test

The blower door itself is a device with a large fan that is used to push air out of the building through the building envelope. The resulting vacuum draws air in though the envelope and the rate can be measured by the blower door. During the test, the manometer, which is the brains of the blower door displays a number, which is the flow in CFM (cubic feet per minute) at a given standard test pressure. This raw number must be adjusted to compensate for altitude and the density differences of different temperature air inside and outside. This number is then used to calculate even more numbers, that we can use to compare the tightness/leakiness of different buildings to each other and to a standard.

Two common metrics for comparing leakage exchange rates are ACH50 (Air Changes per Hour at 50 Pascals) and CFM/SF75 (Cubic Feet per Minute per Square Foot at 75 Pascals).

ACH50: if you are building a house under the 2009 IECC (International Energy Conservation Code) the maximum allowed air changes per hour at 50 Pascals is 7. To calculate the ACH50 from the CFM50 given by the blower door we need to know the volume of the building. Multiply the flow by 60 to convert to hours, then divide by the volume. (ACH50 = airflow (CFM50) X 60 / conditioned volume) If the number is under 7 then it is a pass. In the 2012 IECC the limit jumps to 3 ACH50. That is tight, but the goal to become a certified Passive House is .6 ACH50!

CFM/SF75: if you are working on a commercial project under the IECC or IgCC, you will see a requirement like this; leakage must be under .40 CFM/FT² (2012 IECC) or .25 CFM/FT² (2012 IgCC) at 75 Pascals . Under this metric you need to know the surface area of the building envelope. Multiply that by standard rate to find the allowable leakage flow at 75 Pascals. If the blower door measures a flow less than the allowable, then it’s a pass.

How long does the test take? If the building is setup (i.e. windows closed and mechanical systems shut down) it takes only a few minutes to assemble the blower door. The test takes only a moment if no problems are encountered. If the goal is to find leaks and seal them, then this is the time to walk the building and search of leaks with an infrared camera, smoke or a hand.

When is the building ready to be tested? Technically a building can be tested as soon as there is enough of an envelope to pressurize. If the test is at rough, then incomplete flues and missing door hardware can be temporarily taped over. If the test is at final, and the goal is to get the best score possible, then put off the test until the hardware, fixtures and switch covers are in place. Although workers may be present for the blower door test, all exterior doors need to be closed and stay closed for the duration of the test.

What is blower door directed air sealing? Running a blower door continuously to find and seal leaks as they are found in an existing building.

Why is air sealing important? As it turns out, air infiltration is typically the single most important way to same energy in a building, and it’s relatively cheap and easy to do, and it also increases building comfort and durability.

How does the builder have an affect on the tightness of the building envelope? Through insulation choices, attention to sealing details, mechanical system choices, etc.

How can the score be improved? Let’s talk about the house. We can provide advice, details and specifications to help you minimize air infiltration.

Now the building is so tight, I have to add mechanical ventilation; isn’t that just silly? Its all about control. It’s true we have to exchange some air to keep the Indoor Air Quality high, and some heat will go with in. But if all of that air moves through a mechanical system, then it can be controlled and conditioned. With the help of an ERV or HRV a great deal of the heat can be captured and put back into the building. It is also an opportunity to filter the incoming air with a high performance air filter instead of that air being drawn through unclean cracks and gaps. Also, if the infiltration moves though the insulation, the insulation loses part of it’s ability to resit heat loss.

How much does a blower door test cost? Confluence charges $250 for tests in Glenwood Springs, Carbondale, Basalt, Snowmass and Aspen Colorado. Contact us for quote outside of that area. Fees increase  if additional equipment is required because the building is very large. We provide you with a report for the Owners and the building department with the test results within 24 hours.

How do I schedule a blower door test? Just give us a call or email. Ample notice is appreciated.

multiple blower door test