Aspen no longer a leader in carbon reduction policy

I was hugely disappointed to learn that Aspen no longer seams interested in being viewed as a leader in carbon reduction. The City has just adopted, what is, in my opinion, a relaxed version of the International Energy Conservation Code. The Building Department asked me for data. So I went through 140 different blower door tests and HERS Ratings I had on file to get a feeling for how our new construction is looking. Summary of data below…

locationnumber of testsnumber of tests over 3 ACH50ACH50 averageACH50 lowACH50 High
City of Aspen49263.41.267.08
Pitkin County42203.231.286.37
Snowmass Village874.122.925.71
Town of Carbondale26133.061.165.8

In terms of HERS Ratings- RESNET says the national average score is 61. Colorado had 12,320 (of 206,583) rated homes last year, with an average score of 55. Remember that lower is better when talking about HERS Ratings. Our average HERS Rating score in the Roaring Fork Valley over the past seven years is a 56. So Colorado is better than average nation wide, but the Roaring Fork Valley is behind the state average. Summary of HERS data below…

Number of Ratings in 2016Average HERS Index in 2016
District of Columbia33759
New Hampshire59161
New Jersey3,70461
New Mexico1,14856
New York3,64053
North Carolina13,39766
North Dakota2158
Rhode Island33462
South Carolina7,74068
South Dakota21953
West Virginia12667


Below is a letter sent to the Aspen City Council…

Aspen City Council members,

I intended to speak at the meeting of January 10th but was misinformed about the time and therefore arrived too late. My intention was to recommend denial of the proposed adoption of the 2015 International Energy Conservation Code as amended by the Community Development Department. My preference would be to see the document adopted as written.

My firm, Confluence, has been providing architectural services in the valley for nearly seventeen years. In 2010 the firm began offering energy code compliance services; energy modeling and building testing.

Aspen has adopted a heavily modified version of the code. One that deletes some important tenets of this latest version of the International Building Code. For instance, the requirement for mandatory air infiltration testing has been removed. My professional opinion is that these tests are a valuable check on the condition of the barrier between outside and inside. The data the we have compiled from our work in the valley shows that only about half of that new construction would have passed the 2015 code limits. Research shows us that air sealing is the single least expensive way to reduce the energy consumption of a building.

Aspen’s Climate Action Plan says the community has a goal of reducing greenhouse gas emissions by 80% by 2050. Approximately 32% of Aspen’s emissions come from buildings. If the City were serious about making those goals, then why relax energy conservation building codes at all? Why would the City lowering the bar instead of ensuring that new construction complies with the same code that Pitkin County, the Town of Snowmass Village and Eagle County have adopted?

To me it sounds hypocritical for, Aspen, the home of CORE, the Canary Initiative, Z Green and AREday, not to be doing everything possible to make sure their new construction meets contemporary minimum construction standards.

Final point, it negates the benefits of having an International code system if every jurisdiction completely rewrites the content. It leads to increased confusion, time, money, and potential for mistakes. Why not standardize?

Mark McLain,

Architect & Sustainability Consultant

Pitkin County and Eagle County adopt the 2015 Energy Code

Denver, Boulder and Vail have already done it. Glenwood Springs, Carbondale, Basalt and Aspen will do it soon. But starting today, September 6th 2016, all building permit applications submitted in Pitkin County must demonstrate compliance with the 2015 IECC (International Energy Conservation Code). Eagle County has postponed implementation of the codes until the start of the new year. This will give them time to train staff and educate local architects and builders on upcoming changes. That sounds smart to me, because the changes are not insignificant.

What’s new in the 2015 Energy Code?

Building Department reviews will be looking for new kinds of information on Construction Documents. Drawings will need to tell the story of how a building will be built to conserve energy; insulation, lighting, heating, cooling, moisture management and indoor air quality. Some jurisdictions are requiring that all IECC information be put on it’s own “energy” sheet.

The maximum allowed infiltration rate has decreased to 3 ACH50 and testing is mandatory. The 2009 limit of 7 ACH50 was easy; 3 ACH50 can be a challenge.

Mechanical ventilation is now mandatory. Plan on a HRV (or ERV if you have air conditioning) or some kind of exhaust-only ventilation.

Mechanical systems must be sized with ACCA Manuals J, S & D.

Prescriptive insulation values have crept up a bit in some categories. Chart shows new 2015 values in red.

IECC Prescriptive Insulation Table Headings

IECC Prescriptive Insulation Table

For designer and builders using the prescriptive method of compliance, this means no more 12″ vented roofs. And in zones 6 & 7, no more walls without exterior continuous insulation.

If you want or need to break any of these rules, then you need to choose another compliance path. Using one of the performance path methods (REScheck, COMcheck, HERS Ratings, etc) will make the code easier and more flexible.

Confluence Architecture & Sustainability can help you with all of these facets; from submittal documents to blower door testing. We can help you find the least expensive way to satisfy the building department and inspector, or we can help you design a high-performing net-zero building. Give us a call…


Homes Under Construction

Construction season started with a bang here in the Roaring Fork Valley.  Confluence Architecture currently has 5 homes we designed under construction.  A record for us.  We  are working with a range of clients from owner builders to spec builders.  Here are highlights from recent site visits:

construction excavation

Excavation at Crystal River Valley home






Elk Springs home under construction

Insulation complete and siding in process at Elk Springs home





Working on Finishes at Shaw Spec Storybook House.  Check out that helix stair.





framing stage of constructionFraming underway at the Hilleke Home


Pass the blower door test the first time

If you haven’t been through a blower door test yet, chances are you will soon. As Pitkin County, Aspen, Basalt and Carbondale gear up to adopt the latest round of building and energy efficiency codes. The 2015 IECC (International Energy Conservation Code) have houses going for a maximum of 3 ACH50 (Air Changes per Hour at -50 Pascal) and commercial buildings going for a maximum of .40 CFM/square foot of envelope area at -75 Pascal. Most builders I work with could get to 7 ACH50 without doing anything extra. Getting to 3 ACH50 will take some extra care. If you are unfamiliar with the techniques of air sealing, then read up or get an expert on the team. A great place to start reading is the ENERGY STAR Thermal Bypass Checklist . Awesome document- do this stuff and you will pass the blower door test the first time.

Test day

I’m often asked, “what do I need to have done before we test?” Completely done, done, done is ideal; but in reality…  below is my checklist of this that should be done before testing so test results are not significantly degraded:

  1. doors and windows installed
  2. door and window hardware and weatherstripping installed
  3. door thresholds installed
  4. hatches to unconditioned attics and crawlspaces installed and gasketed
  5. dampers in place
  6. fireplace doors installed
  7. plumbing traps filled
  8. conduits leading outside sealed
  9. air handlers and ductwork complete
  10. light fixtures installed
  11. plate covers installed
  12. any other gap, crack or hole between inside and outside that you can find

Setting up the Building

When we test a building for air infiltration the building must be setup in a prescribed fashion. The IECC has it’s section (2009 IECC R402.4.2.1 or 2009 IRC N1102.4.2.1)  that describes how to setup a house. RESNET has their official protocol as well, the document ANSI/RESNET/ICC 380-2016.

  1. Exterior windows and doors, fireplace and stove doors shall be closed, but not sealed with tape;
  2. Dampers shall be closed, but not sealed; including exhaust, intake, makeup air, back draft, and flue dampers;
  3. Interior doors shall be open;
  4. Exterior openings for continuous ventilation systems and heat recovery ventilators shall be closed and sealed;
  5. Heating and cooling system(s) shall be turned off;
  6. HVAC supply and return registers shall not be sealed.

Running the test

I usually takes me 20-30 minutes to set up the blower door equipment and check that the house is prepared. I need an exterior door that is not too small or too big to set up in, power nearby and a space to work in. If the house is more than 5000 square feet or so, I will set up double fan equipment.  Then I will need to shut down the air handler and exhaust fans. At this point, anyone opening a door would void the test. But typically I only need the doors closed for five minutes to get an accurate reading. If it hasn’t been done yet, I will need the drawings to calculate the volume of air inside the house. Then do the math; flow (the results of the test) X 60 divided by the volume of the house = the number of air changes per hour. In the end, I create a certificate, that need to go to the building official.

If you want/need someone else’s eyes on the job, then give us a call. Confluence Architecture has a lot of experience with construction detailing, building testing, improving test results and also does HERS ratings, RESchecks, COMchecks, blower door tests, duct blast tests, IR camera inspections, etc.

Confluence Now Offers Solar-Powered Site Visits

Confluence Architecture & Sustainability has been electrically net-zero for a while. Now our surplus solar electric is being used to charge our new Electric Vehicle.

Nissan Leaf

A Gunmetal Grey Nissan Leaf with a level 2 charger to go with it.

Architectural site visits, construction inspections and blower door testing from Confluence will now be carbon neutral from New Castle, Glenwood Springs, Carbondale, Willits, Basalt to Aspen!

Confluence Architecture wins Houzz Award

Houzzbadge_22_8Confluence Architecture of Carbondale Colorado awarded Best of Houzz 2016 for customer service. The Best Of Houzz is awarded annually in three categories: Design, Customer Service and Photography. Design award winners’ work was the most popular among the more than 35 million monthly users on Houzz. Customer Service honors are based on several factors, including the number and quality of client reviews a professional received in 2015. A “Best Of Houzz 2016” badge will appear on winners’ profiles, as a sign of  their commitment to excellence. These badges help homeowners identify popular and top-rated home professionals in every metro area on Houzz.



Marble Distilling Company Design Wins Award

Marble Distilling Company







USGBC Colorado honored the Marble Distilling Company design for its exceptional implementation of sustainable technologies with a 2015 Commercial Real Estate Award.  The distillery’s integrated systems approach utilizes the heat from the distilling process to heat the distillery, tasting room and Inn as well as recaptures that heat and water for utilization in the distilling process and for domestic use.  With these measures, the building is 85 percent more efficient than local code requires.  Confluence Architecture is honored to be part of a great team that made this possible.  Congratulations to Marble Distilling Company, Energy and Sustainable Design and the whole team! Read more here.

Colorado Projects Under Construction

July 2015 has been the busiest summer ever for Confluence Architecture in our fifteen years of operation. We have two additions and four new homes presently under construction- plus three more homes to break ground soon. Not to mention a healthy dose of inspections, commissioning, HERS ratings and blower door tests. The projects below are; crane in Arrowhead Village Edwards, concrete pumper truck between Redstone & Carbondale, near Sunlight Ski Resort Glenwood Springs, Elk Springs near Glenwood Springs, Marble Colorado and one for an old friend in Arkansas.

Arrowhead Village signArrowhead ~ Edwards, Coloradopumper-truck
Near Sunlight Ski Resort ~ Glenwood Springs, ColoradoElk Springs ~ Near Glenwood Springs, ColoradoMarble, ColoradoFor a friend in Arkansas

Thanks to everyone involved for the hard work and fine craftsmanship!