VOLKsHouse = Passive House

Introducing the VOLKsHouse

SUSTAINABLE HOUSE BREAKS THE COST BARRIER

VOLKsHouse is a response to America’s overuse of energy resources and the typically higher cost of green construction. Based on energy-conserving Passive House technology, it was built to prove that eco-construction can be fully cost-competitive with traditional construction and to pioneer healthy and affordable green housing. Designed by award-winning MoSA Architects in Santa Fe, it is the first certified Passive House on the New Mexico market using 90% less energy for heating and cooling, costing 6.5% less per square foot to build than a conventional home and designed to give power back to the grid. Energy performance is monitored daily and financial records will be audited to verify savings. VOLKsHouse is the third cost and energy-saving MoSA Passive House and plans are being developed to build sustainable housing in cooperation with the New Mexico Housing Trust. VOLKsHouse sets a baseline for driving down construction costs, serves as a model for training and educating builders, establishes new standards for affordable housing, and unlocks economic potential for the expansion of green living and eco-construction. If a Passive House uses far less energy and costs less to build, there’s no longer any reason to build anything else.

Partner and Investor: Bob Schneck

Architects: Jonah Stanford & Vahid Mojarrab, MoSA – Mojarrab Stanford Architects,
Santa Fe, New Mexico

Project Location: Santa Fe, New Mexico

Construction Cost: $161 per square foot

Total Estimated Sales Price: $415,000

Estimated Site Energy Use: 0

Completion Date:  April 2012

The VOLKsHouse is a site-net-zero  single family residence being built in Santa Fe New Mexico. The project has been designed to exceed Passive House requirements for certification which serves to bring the overall projected energy use down by approximately 85%. An integrated solar thermal system is designed to provide 100% of the remaining heating and domestic hot water needs. The balance of energy use, mostly due to domestic use such as lighting and cooking is generated by a small PV solar system.  All of this is currently under construction for approximately 20% less then typical construction costs and is designed to meet the the financial needs of workforce Housing in our area.

Please follow along as we detail the project and construction techniques used in Passive House construction, as well as discussion of how an integrated approach to sustainability can lead to dramatically reduced construction costs.

Helpful Links:
MoSA – Mojarrab Stanford Architects: www.Mo-S-A.com
Passive House Initiative Project (PHI): mo-s-a.com/category/passivehouse/
Passive House Institute, Darnstadt Germany: http://www.passiv.de/07_eng/index_e.html

Contact:
Jonah Stanford, MoSA, Santa Fe, 505-577-4295; jonah@mo-s-a.com
Bob Schneck, MoSA, New York, 212-786-0287; bob@mo-s-a.com

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VOLKsHouse – Fact Sheet

VOLKsHouse is a revolution––a prototype for America’s affordable, net-positive, sustainable future. Award-winning MoSA Architects integrated Passive House conservation strategies and solar hot-water and electrical systems with contemporary design to create an exceptionally efficient home at lower-than-market construction costs.

Energy and Cost Efficient:   
Uses 90 percent less energy and costs 6.5% less than a comparable conventional home in Santa Fe.  German-engineered Optiwin 3-layer windows and doors deliver some of the world’s highest true R-values (standard measure of thermal efficiency).

Deep Green:
Certified as a Passive House, the global standard for energy efficiency, and rated Emerald by the National Home Builders Association.

Solar Energy:
Maximizes energy savings with passive-solar design, solar hot water and solar electricity.

Energy Recovery Technology:   
Minimizes thermal losses and maximizes gains while maintaining unprecedented indoor air quality.

Comfortable:    
Ensures comfort in every season in every room with a well-insulated thermal envelope.

Healthy:  
Uses only low-VoC (volatile organic compound) finishes.

Economical:   
Protects owners from rising energy costs.

Beautiful:  
Designed by MoSA, award-winning Santa Fe architects.

Special Features:
Includes energy-monitoring system and efficient LED lighting.

Building Specifications:
1,717 square feet (conditioned); 3 bedrooms/2 baths; two-car garage; rooftop patio.

Location: 
1351 Ferguson Lane on Agua Fria, Santa Fe, New Mexico.

Investment in the Future:  
Pioneering the way forward to sustainable living

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Site Selection for VOLKsHouse

Site evaluation for Volks House Land purchase

Once Santa Fe was selected as the location for the VolksHouse a search for property began. The Ferguson Lane parcel had many extremely favorable characteristics that made it immediately attractive.

Orientation:  Though perfect solar orientation is not required for Passive House construction, it is difficult to say no to as much free energy as you could ever use. The property sits on a corner lot. The street on the south side of the property ensures that this solar energy will (in all likelihood) be there for the life of the home and will not be blocked by future development.

Connectivity: The site had amazing local connections to the community. The east property line abuts  a  10 acre park with orchards and playgrounds. This park also connects the City’s extensive bike trails that lead along the Santa Fe River that can be followed directly to the down town plaza.

Community: The selected parcel was the last lot available in a well establish and tight knit community of approximately 35 house along a single cul-de-sac street. The neighborhood was very receptive and supportive to the intentions of the project which is invaluable for such a project. The lot also had high visibility that would generate curiosity.  Curiosity is good. It leads to other things.

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VOLKsHouse data

VOLKS House floor plan

The VolksHouse contains three bed rooms, 2 baths, and has 1,650 sqft of conditioned space. The main hub of the mechanical systems resides in a simple ”mud room” between the two car garage and main house.

System Design comment:

A primary approach to affordability regarding passive house construction or sustainability in general for that matter is simplicity. If you find that the systems are getting complicated then stop, and think about how you got there. Generally, we find that over complication in system design comes from following a decision making path that started with something small and snowballed.  If this happens, we call it “hoop jumping” and will try to revisit the original perimeter to see if it couldn’t be eliminated. Generally it can, or it can be shifted.

 

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Foundation Insulation #1 – Frost Skirt

This is the permitter insulation for the Volks Passive House.   It uses 2 lb. EPS foam. It is thick enough that no other form work needs to be used for pouring the slab. It is protected on the exterior with a factory painted metal sheeting. The metal serves to protects the foam from moisture, bugs, and looks good as some of it will be exposed.  The foam is placed on a bed of sand to allow for drainage, and ease of leveling.  The black tube running inside is the EPA recommended radon system, and will be covered in clean gavel. The gravel layer for the radon system acts as a capillarity break for the additional rigid insulation that will be placed under the slab. 

Frost Skirt for Passive House

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Foundation #2 – Under Slab Insulation

We have found that the detailing and execution of the under-slab insulation and air-barrior is the best place to start educating crews about the critical paths impacting Passive House Construction.  We learned from previous projects that the poly used under the slab was susceptible to damage just though ware and tear. For this reason we started using a reinforced material and placed it under the slab insulation.

Passive House Slab Installation

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Foundation #3 – Slab insulation detail

 

Slab edge after pour

 

 

 The lower photo shows a typical detail at thickened slab sections designed to carry bearing walls. The perimeter “foundation” is only 8″ thick with the rest of the slab being 4″. On the Volks House we found that 4″ of rigid insulation provided the correct balance between heating and cooling. Too much insulation and we would not benefit from the natural cooling of the earth during the summer, too little and our heating loads went up.  Due to our high solar heat gain potential we are able to regulate heating easier then cooling. 

Corner and thickened Slab Detail

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Framing #1

The framing for the Volks House is fairly typical, we follow standard practice for reducing material because of cost, thermal bridge reduction, and resource efficiency by framing with 2-stud corners, headers on only bearing walls, etc. But the rest is fairly normal. The Volks House uses 2×6 framing at 24″ OC and in this case TJI joists. The framing cavity only carries 35% of the R-value our thermal envelope. One of the most challenging aspects of meeting the Passive House Certification Process is the elimination of thermal bridging. This wall section represents an approach that we feel is extremely repeatable.

Photo of interior framing

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Framing #2 – thermal Isolation – Passive house / Passivhaus

As discussed before regarding thermal bridge isolation, the Volks House has an attached two car garage. We do not want any of the garage structure’ (that resides outside the  thermal envelope) to penetrate the thermal envelope of the House.  For this reason the whole structure of the garage is set off of the house by 10″. In later photos you will see that this “gap” is filled with the rigid insulation sheets that act as the primary thermal envelope.  The house is on the left side and the garage on the right.

thermal break between house and garage

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Framing #3 – Airtight Layer

The exterior of the structural framing receives the structural sheeting that also acts as our air-tight layer.  In this case we used Zip-Panels and could not have been more happy with the result. The surface is extremely stable, easy to inspect, FSC certified, and relatively breathable for a OSB.  Once the air-tight layer has been installed, all seams sealed, windows installed, electrical, and plumbing rough-in completed we perform the blower door test. We need to make sure that we pass the blower door test at this point so that any gaps can be filled.

air-tight layer

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Air-Barrier #1 windows

We decided to install the Optiwin windows flush with the outside of the air-barrior for the Volks house for ease of installation and simplicities sake. The are not perfectly aligned with the cent of the thermal envelope, however are fairly close.

window installation detail

Optiwin window after installation

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