Designing for Net Zero

or just a great HERS / ERI score.

 

It’s not easy to show energy code compliance in climate zones 6 and 7. Especially if you’re working in a jurisdiction that has adopted above-code requirements. Designers here’s an exercise to help get your design on its way to IECC compliance and beyond. On your next project, before starting your typical design process, rough out a schematic design, but forget all clients wishes, ARC guidelines, height limits, etc. and design for energy conservation by substituting the following parameters…

Envelope

  1. Make the thermal envelope a simple, regular volume.
  2. Share assemblies with other structures, when possible, but make that party assembly very airtight.
  3. Follow the prescriptive code for air barriers and insulation levels.
  4. Maximum 20% glazing; 20-30% glazing; plan for really, really good windows, over 30% plan for great triple-pane windows.
  5. Put as much of the insulation on the outside of the assembly as you can, or frame with Efficient Framing techniques or use alternate techniques that reduce thermal bridging like; ICFs, SIPs, Larson trusses, adobe, strawbale, etc.
  6. Make the roof within 20° of optimal pitch (10:12 to 14:12) and orientation (160°-200° south) for solar, free from obstructions and penetrations.
  7. Use passive solar heating techniques when possible; insolation managed by proper overhangs and low-e coatings on glazing.

Equipment

  1. Plan for no gas or propane, all electric house.
  2. Use no snowmelt.
  3. Locate the mechanical room, in the core of the house, minimize distribution runs. Give plenty of room to equipment for service. Easy access; no hatches, ladders or crawling.
  4. Locate the outdoor side of the heat pump equipment. Protected from snow and ice.
  5. Don’t use site-built forced-air ductwork if you can avoid it. Radiant or ductless preferred. If not, don’t combine ductwork with garages, ventilated attics or ventilated crawl spaces. Insulate it and seal it very well.
  6. Plan for a stand-alone occupant ventilation system, with occupant controls and easy access for filter cleaning; not in a crawlspace or attic. Ducting this is okay.
  7. Heating; use GSHP (ground source heat pump) if you can. If not, use ASHP (air source heat pump) and passive heating techniques.
  8. Cooling; skip it altogether if you can. If not, use ASHP, evaporative and passive cooling techniques.
  9. Hot water; use thermal solar per-heat if you can. If not, use HPWH (heat pump water heater). Ducting this is okay.

Electric

  1. Use no heat tape.
  2. Use ENERGY STAR appliances. Keep refrigeration loads as low as possible. Induction range and convection oven.
  3. Plan for low flow plumbing fixtures and fully insulated lines.
  4. Plan for DWHR (drain water heat recovery)
  5. If hot water runs are still long enough to require recirculation, use a smart pump with occupant sensors in the bathrooms and a temperature sensor to control the pump runtimes.
  6. Maximize the PV array size.

Designers: Now you have a schematic design optimized for potential energy conservation. As you move on to your typical design process, keep this design in the background. Know that the more your design develops away from the energy conservation architype, the harder it may be to reach specific performance goals.

Note to Structural Engineers: Your challenge is to help the Architects keep as much steel and wood out of the thermal envelope as possible. Support several inches of Continuous Insulation, even behind stone veneer. Keep the foundation completely covered in insulation, even at patios, doors and behind stone veneer.

Note to Mechanical Engineers: Your challenge is to help the Architects reduce all equipment loads, reduce runs and maximize efficiency. Investigate new technology and equipment and learn how to work with it. And help us all reduce a house’s dependence on gas.

Getting to Zero

Confluence Architecture was instrumental in turning an old 1970 energy hog home into a an efficient, low energy use residence.   The project qualified for $12,000 in  grants from CORE and $7,092 in rebates from Holy Cross Energy.      The home is fully electric and uses air-source heat pumps for heating and cooling.  It is projected to be net-zero. Confluence was responsible for planning, architecture and energy modeling on this home.

Before

           

 

After

      

New Home in Aspen Glen Completed

We are excited to showcase a new home we designed in Aspen Glen.  It is a 2500 sf, 3 bedroom home for a young family. The form of the home has 2 axis to respond to a challenging parallelogram lot. The home includes  indoor/outdoor features including an in and out bar window between the kitchen and rear patio. The master bedroom has a wrap around deck with views oriented towards t Mount Sopris.

     

 

A new home for Little Blue Preschool

Confluence Architecture along with local non-profit  Blue Lake Preschool  is honored to announce that after searching  for 5 years they were able to find a permanent location. Last September, Blue Lake Preschool  acquired the  property at 55 N 7th st, which happens to be the former residence of Mary Ferguson, a Carbondale icon. She was born at Spring Gulch in 1906, taught in one room schoolhouses, was a town council member, a volunteer and historian.  We find this connection to be a valuable  continuation of  Mary’s love of teaching.

Construction is now underway on the addition and remodel to to transform this 1950’s ranch home into an energy efficient  healthy and cozy preschool. Some of the energy efficiency  attributes include  addressing air circulation and filtration by utilizing a HRV system with Merv 13 filter, and upgrading  the insulation.  We seek to replace all the flooring with environmentally friendly natural linoleum and will use zero or low VOC paints.

Confluence Architecture has thrown its support behind this worthy project by contributing our professional services of  planning, property analysis, and Architectural services.  Blue Lake Preschool  is seeking funding to assist with construction.  This permanent home will allow Little Blue to increase the number of infant care spaces in Carbondale, a critically underserved demographic. We encourage all to donate to this worthy cause.  Donations can be made at Blue Lake’s website  https://bluelakepreschool.org/donate.

Energy & Sustainability Services

Recently more jurisdictions have adopted the 2015 IECC or the IgCC and we have been helping several architects & designers with energy and sustainability code compliance.

Go custom! You don’t have to follow the recipe. Make the energy code work for your project.

Farm out the energy work to Confluence. We will be responsible for any or all of these, bring value to the performance of the building, and take the load off of your hands:

  • Energy code compliance
    • Infiltration (blower door) testing
    • Assembly UA trade-off (calculation software)
    • Total UA trade-off (REScheck or HERS Rating)
    • Performance path compliance (REScheck or HERS Rating)
    • ERI path compliance (HERS Rating)
  • Code compliance/optimization and Construction Documents
    • Ventilation calculations
    • Sealed crawlspace & ventilation details
    • Continuous Insulation details
    • Back-ventilating siding and attachment details
    • Efficient framing details
    • Fenestration flashing details
    • Radon mitigation details
    • Thermal and pressure envelope delineation
    • Vapor retarder specifications
    • Air-sealing details
  • Local/municipal Green/Efficient Building Checklists
    • Carbondale, Basalt, Town of Snowmass Village, Telluride, Mountain Village
  • Above-code/Net Zero design and certification
    • LEED, Passive House, HERS Rating, etc.

Recent work…

We have recently gotten the chance to photograph some recently completed work.

The Basler Residence at Elk Springs, Garfield County, Colorado…

 

And this storage banquette…

Here’s a house going up in Oak Meadows…

 

 

Confluence Architecture’s Design Process

Predesign

Typically, the process begins with walking the site and talking about the vision for the structure. If it is an undeveloped lot, we often identify the ”power spot”, a point on the site that relates the conceptual center to the design. The program is developed, that is the recipe of spaces and requirements for the house.

 

Schematic Design

The first schematic sketches are based on; site forces like the sun, views, trees. Civil issues like vehicular access, topography, and drainage. Tangible issues like program, size, and scale. Local vernacular. Confluence typically develops several schematic designs for residential projects.  The diagrams take the form of two dimensional plans and three-dimensional massing models.

Example of schematic site plan

Examples of schematic massing model

Design Development

During design development, the multiple design directions studied in schematic design coalesce into one design direction.  The 2-D plans and 3-D model are developed with more detail showing fenestration and exposed structure.

Example of design development plan

Examples of design development models

Construction Documents

During the Construction Documents phase, the details and materiality of the design are created.  These documents are used for building department, HOA approval, and ultimately to build the home.

Construction Documents

Beyond Construction Documents

On occasion, a project needs more description beyond construction documents.  Confluence can do fully rendered models for sales and advertising, interior drawings and details and more.

Marble Distillery Inn – rendering of hotel room

Photo of hotel room

 

Marble Distillery Inn – rendering of tasting room

Photo of tasting room

Sustainability

We are committed to keeping up with the state of the art in energy efficient and sustainable construction. Our construction documents will include details for building in an air-tight and durable manner.

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 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.