Lakeridge Trail

When we purchased our home in Lake of the Pines, we did so for the location, not for the house.  The crazy 1975 design included 2 oversized gas furnaces that short-cycled so often the house would never get warm.  Access to one was through a 20"x20" hole in the foundation wall four feet above the basement floor, while the other, located next to the master bedroom, sounded like an airplane taking off every time it came on.  Most of the windows were single-pane and leaky, and most of the beautiful view of the lake through them was blocked by a catwalk.  With ants and wasps living year round in the roof, not to mention rodents showing up every few months in the basement, we had no intention of tolerating the status quo.

Our passion for energy efficiency and sustainability led us to Brian Fuentes of Fuentesdesign Architecture.  He had been refurbishing houses according to his Passivhaus training thoughout the Boulder, CO area for ten years, and he had been getting many requests for proposals due to the need for rebuilding after the Northern Colorado flood of Sept. 12, 2013.  So we felt lucky when he decided to take on scraping and rebuilding our home to net zero standards.

We knew we wanted to take advantage of our dramatic views of Allens Lake and the eastern plains of Colorado, and to let the outdoors in without compromising our netzero goal. We were delighted to learn about Zola windows, and incorporated many floor-to-ceiling windows including a 16 foot sliding door. All the windows are triple pane and highly efficient, providing natural light to all living spaces. Brian led us on an exciting path of discovery and design, including a very tight envelope, a ground source heatpump leveraging three geothermal wells for heating cooling and domestic water heat. We leveraged a variety of insulation layers, a high-impact/wind resistent efficient roof, energy efficient appliances, water efficient low-flow toilets and fixtures, and beautiful finishes featuring sustainbly sourced acacia hardwood floors, natural fiber carpets, LED lighting throughout, and beetle-killed pine ceilings. In addition, the garage includes a 220V outlet for EV charging (when we get one!).  We also reduced our own square footage while maintaining our property value by converting the basement into a separate efficiency-style apartment with an amazing view to be used as a rental or for an aging parent or caretaker. We decided to include a larger solar array than strictly needed, so we feel better about our use of appliances, including a hot tub and steam shower!

The result is stunning. We relish each sunrise, the bright open spaces, the quiet interior, and the consistent draft-free year-round comfortable temperatures.  Consequently, we hope that our home can be a model for other net zero homes in the state of Colorado and elsewhere.

Quick Facts

General

Location
2861 N Lakeridge Trail
Boulder, CO80302
United States
Building Type single-family residence
Project Type Zero Energy
Basis of Performance Claim Modeled,
Bedrooms 4
Conditioned Floor Area 3 820

Energy Summary

Energy Data Type Estimated,
Renewable Energy System Type(s) Photovoltaics,
Ratings
Annual renewable energy generated 14 200

Envelope and Mechanicals

Subslab assembly

Over existing garage slab was a vapor barrier followed by 12" EPS then conventional floor framing bearing on existing walls, R 52. Existing sloped crawlspaces 3" ccsf (R20) over vapor barrier on ground. There was an existing basement slab that remained uninsulated of 723 sf.

Foundation wall assembly

basement walls 4" polyiso against concrete with dense pack cellulose in 2x4 interior stud cavity

Above grade wall assembly

Remodel/new construction 4" polyiso nailbase over 2x6 OVE 24" O.C. framing with netted and blown cellulose

Door Assembly

Zola Thermoclad

Air Changes per hour, ACH50 0.49
Original front view Original interior cat walk Original basement leaky windows Original entrance to furnace Under construction 2"x6" construction with original chimney Southern overhang for solar shading Nail base and seal before stucco First window installed Zola kitchen window from inside 18' Zola slider Impact resistant composite roof Southern deck Closed-cell foam on basement wall Foam in trusses Frontal view under construction New kitchen under constuction Finished master bedroom with alcohol fireplace Finished kitchen External 90% light-blocking remote-control shades Finished frontal view

Project Team:

Other Team Members:

Ratings:

Awards:

Poudre Valley REA Solar Rebate

Completion

Completion Date: Wednesday, July 29, 2015

Scope

IRC 2012 with Boulder County Amendments, Type VB, not sprinklered. This residential project involved scraping an existing home to the slab-on-grade foundation except for the chimney. Other than minor foundation repairs, the primary element added was a 624 sq ft garage.

Type of Construction Renovated,
Number of buildings 1
Floor area of each building
Bedrooms 4
Stories 2
Conditioned Building Volume 48 586
Conditioned Floor Area 3 820

Location and Climate Details

single-family residence

Address
2861 N Lakeridge Trail
Boulder, CO80302
United States
Location Type Suburaban
Climate Region Zone 5
Köppen Climate Type Dfb
Lat. / Long. POINT (-105.2912806 40.1382487)
Elevation 5 802
Solar Insolation 5.52 kWh/m2/day
Annual CDD and Base Temp 1020 | 65 deg F
Annual HDD and Base Temp 5427 | 65 deg F

Site

Site Conditions:

previously developed land, lake/pond,, preexisting structure(s),

Site Description:

This home is in a rural residential area with 80 homes around 40-acre Allen Lake. The house is located on a hillside 140 ft above and to the west of the lake.

Monthly Energy Data and Utilities

Energy Data Type: Modeled,

Electric Utility: Poudre Valley Rural Electrification Assoc. (PVREA)

Gas Utility: N/A

Renewables and Energy Balance

Renewable Energy Sources:Renewable energy is generated within the building footprint (e.g. solar PV on the roof),

Renewable Energy System Description & Details: The PV system consists of 40 roof-mounted Kyocera KD255GX_LFB2 panels with 4 Fronius IG Plus A 10.0-1 inverters.

Annual renewable energy generated 14 200
Annual Renewable Energy Generated Data Type Estimated,
Power Rating 10Watts
Renewable Energy System Type(s) Photovoltaics,
Source of Annual Production Data Production value was estimated by Namaste Solar, the array installer.

Walls and Roof

The building envelope involved constructing 2x6 walls with polyiso nailbase over existing slab and Zola windows. Outer finish is fire retardant stucco.

Subslab assembly

Over existing garage slab was a vapor barrier followed by 12" EPS then conventional floor framing bearing on existing walls, R 52. Existing sloped crawlspaces 3" ccsf (R20) over vapor barrier on ground. There was an existing basement slab that remained uninsulated of 723 sf.

Subslab R-value 52.00
Slab edge assembly
Slab edge R-value
Foundation wall assembly

basement walls 4" polyiso against concrete with dense pack cellulose in 2x4 interior stud cavity

Foundation wall R-value
Above grade wall assembly

Remodel/new construction 4" polyiso nailbase over 2x6 OVE 24" O.C. framing with netted and blown cellulose

Above grade wall R-value 35.00
Cathedral ceiling assembly

18" netted and blown dense pack cellulose in trusses

Cathedral ceiling R-value 64.00

Windows and Doors

Window Assembly:

Zola Thermoclad

Door Assembly:

Zola Thermoclad

Average window U-factor 0.15
Door U-Factor 0.15
Door Area 124

Mechanical Systems

Space cooling - Manufacturer & Model ClimateMaster Q45 Trilogy ground source heat pump,
Space heating - Manufacturer & Model ClimateMaster Q45 Trilogy ground source heat pump,
Domestic hot water - Manufacturer & Model ClimateMaster Q45 Trilogy ground source heat pump w/integrated GDHM 80-gal tank with 10 kW electric backup
Domestic hot water - capacity 80
Ventilation - Manufacturer & Model ERV Ultimate Air 200dx,
Lighting Manufacturer and Model 95% LED,
Lighting Efficiency
Mechanical Equipment Installation Details and Comments

Forced air hard ducted system for heating and cooling; separate ERV duct system with flex duct at termination for noise control. ERV jumper ducts at bedrooms.

Envelope

Air Changes per hour, ACH50 0.49
Air Changes per hour, CFM50 399.00

General Process

The existing house 70's with 11 different floor levels and poor to non-existent insulation. By using existing garage area for a new kitchen and dining area, views of the nearby lake were captured with minimal new excavation and concrete work. The bulk of the house was completely rebuilt on the existing foundation on a single level for accessibility with a spare bedroom in the basement for guests.

Design for Adaptability:

Software Tools

Software Tools:

General modeling information:

Lessons Learned

Outcome of Project Goals:

Discrepancies:

Rebates and Financial Incentives

Federal incentives
Local incentives
State incentives
Utility incentives
Other incentives
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