KEC Week 50

Work this month focused on the final mechanical, electrical, and plumbing rough inspections.  This allows  sheetrock on walls and ceilings to continue.  Permanent power from the town electric grid has been energized and we are in the process of switching the building from temporary construction power to permenant power.  The elevator installation is beginning.  Millwork is being delivered for the labs and classrooms.  Ceramic tile in the bathrooms will start shortly.  Exterior work focused on continuation of the PV panel installation.  The final exterior trimwork on the siding is nearing completion.  Site preparation for spring sitework and landscaping is underway.  

[north elevation]

[courtyard west elevation, sunshades in progress]

[lab wall rough-in, ceilings sheetrocked]

[pulling electrical distribution to electrical panels]

[Marvin entries installed at vestibule]

[pipe insulation in seminar soffit]

[MEP rough-in in seminar soffit]

[dorm room sheetrocked and taped]

[east elevation dorm wing]

[courtyard as seen from the south path]

[ Marvin door at faculty entry]

[PV array installation]

[sheetrock and taping at labs]

[sheetrock and taping at labs] 

[installation of mechanical piping behind lab casework]

[taping at labs]

[fireboot enclosure at recessed lights in faculty to maintain fire ratings]

[dorm corridors]

[dorm corridors]

[above ceiling catwalk over dorm bathrooms]

[finishing touches on faculty terrace siding]

[basement corridor]

[dorm corridor]

KEC Solar PV

The ground mounted photovoltaic (PV) array is located just north of the building site, facing South for optimal performance conditions.  It is a 296kW array and will produce all the energy consumed by the KEC over a year, making the facility Net-Zero Energy, which is expected to be 44.7 kBtu/sq ft annually.  The array is connected to the grid and will produces more energy than needed in peak summer months, spinning the electric meter backwards.  Then in the winter when solar production is lower the meter would spin forward drawing down on the account balance.  The goal is at the end of any given year, the total energy produced and consumed on site balance out to zero.

Since PV is a fairly expensive up-front cost still, it is important to reduce the energy needs as much as possible.  The KEC demonstrate a number of technologies to reduce energy needs including building siting, high performance building envelope, ground source heat pumps, earth duct, evacuated tubes, passive ventilation, and sun shading to name a few.  Another key element is a commitment from the user group to accurately forecast the expected energy usage and adhere to these guidelines.  This will be part of the living and learning experience for those at the KEC.  Ultimately, the up front costs are offset by onsite energy production and the overall benefit to avoiding consumption of fossil fuels is a tremendous benefit.

Below are progress shots of the array being installed.

[ pv ductbank from main electric panel to pv switch ]

[ concrete encased pv ductbank ]

[ pv switch ]

[ pv field prep ]

[ pv framing ]

[ pv framing ]

[ pv framing ]

[ pv framing ]

[ pv framing ]

[pv modules on site] 

[pv array installation] 

[pv array installation]  

[pv array installation]  

[pv array installation]  

[pv array view from faculty terrace] 

[pv array installation] 

[pv array viewed from the observation deck]

[pv array viewed from the observation deck]

[screening to protect wiring]

[disconnect switch]

[pv panels]

[inverter]

[pv array]

[black powder coated steel support rack]

KEC Wall Framing and Insulation

When building a net zero energy building it is important to properly insulate the building.

The energy efficiency of an entire wall assembly has been documented by Oak Ridge National Laboratory (ORNL). The testing method takes into account energy losses for the structural members, corners, joints and around windows, not just the value of the insulation. Results of these tests are shown below.  They provide R-value recommendations by zip code.  They also provide a whole wall R-Value calculator

The KEC has a doubled framed wall system.  This means the exterior wall is framed with 2x6 FSC wood studs at 16" on center.  Then an interior wall is framed with 2x4 FSC wood studs at 24" on center.  There is a 1" air gap between the interior framing and the exterior framing to prevent thermal bridging.  Some structures can get away with a 2x4 on the exterior wall, however with the long spans and the stone veneer this was not structurally possible for this project.

This double stud wall also allows a deeper cavity space for additional insulation.  Instead of standard fiberglass batts, we used a combination of open cell and closed cell spray insulation.

3" Closed cell insulation is Demelic Heatlok Soy 200 on the inside face of exterior sheathing
6" Open cell insulation is Demelic Sealection 500 was then applied.  This allowed a total insulation depth of 9" and provided an R-44 wall system.  This is nearly triple the insulation value of standard construction.

Where 3" of closed cell and 6" of open cell could not be achieved due to physical job constraints i.e. framing conditions, 6" of closed cell was used which also achieves an R-44.

The blend of open cell and closed cell is more cost effective than just 6" of closed cell.  And while the open and closed cell spray insulation is more expensive than fiberglass batt insulation, the increased energy performance reduces the energy cost to condition the interior space and makes the net-zero project goal achievable.

Interior wall and ceiling insulation is a combination of both Knauff EcoBatt and Roxul Mineral Wool depending on the location and rating requirements.