Northfield Passive House Farm

A new Passive House becomes the sustainable and resilient hub of an established rural farmstead.

Owned by the family since the 60s, the hub of this farmstead was a tired farmhouse, which had been patched and updated many times during its life. When we started work with the owners they had already made the decision to replace the structure, as its bones did not support further remodels or additions.

Old farmhouse prior to demolition

Concept

At 4,500 useable square feet, the new home is more spacious and versatile than its predecessor. In addition, it features attached front and rear porches, as well as a multi-purpose garage connected via a breezeway. These amenities will enable a better integration with the site and the constant back and forth between inside and outside.

The serene setting on a modest rural lake and in the midst of farm fields provides a wonderful backdrop for a design that is evocative of contemporary hints as much as the character of the grown hub in the center of the farmstead—reflecting the husband’s Swiss origins as much as the wife’s midwestern roots.

Fit for a family of four and then some, this two-story building offers an open living, dining, and kitchen area with views of the yard to the south—framed by rows of mature trees. Mudroom, pantry storage and laundry spaces, as well as a bedroom suite with bath provide a high-level of functionality right on the first floor. The private second floor replicates the bedroom suite layout, and adds additional bedrooms and baths, as well as a family room and storage spaces. A full basement holds more storage, the mechanical room, as well unprogrammed space for future use. Views to the East capture lush woods—while windows on the West side offer a glimpse of the lake. Garage, breezeway, and first-floor storage spaces are geared towards functionality to enhance efficiency for everyday work and living on the farm.


Construction

The home is designed to meet the Passive House building energy standard. R-55 above grade and R-50 below grade walls are complemented by an R-35 structural slab, and an R-85 trussed cold roof. The main structure and garage are constructed from insulated concrete forms (ICF) and clad with an exterior insulation and finish system (EIFS), while the attached porch structures are conventional wood-framed spaces. Aluminum clad, wood Passive House windows provide an average R-value of 7.7 and 50% solar heat-gain coefficient. Motorized exterior shades help temper solar heat gains throughout the year.

Due to the size of the building, we designed a modular commercial balanced heat-recovery ventilation system. Automated controls measure contaminants and humidity levels to provide optimal ventilation rates. One unique feature of this system, which TE Studio co-designed with Lüfta’s Thomas Brandmeier and with input from the homeowner—an electrical engineer—is the addition of a heat-exchanger, which can provide small heating and cooling loads. This means that on moderately cold, or hot days, the ventilation system alone can temper the space. An earth tube provides additional preheating, pre-cooling and dehumidification based on season—making the ventilation system extremely efficient.

The home’s floors are equipped with an in-floor heating system, that can also be used to cool the structure during the warmer months. Energy for all of this is provided by a ground-source heat pump, which also produces domestic hot water. With the Passive House solely fueled by solar heat gains, ground-sourced energy and electricity, the large outdoor propane gas tank was removed. In summary, this Passive House with its systems provides a very low specific source energy demand, allowing the site to be powered by a suggested grid-tied, roof-mounted photovoltaic system, which over the course of an average year can provide enough energy to fuel it all.


Collaboration

TE Studio enjoyed great collaboration with Peak Building Products during the design of this project. Stephan and Robert Tanner helped source windows, exterior motorized blinds, as well as shade boxes that house the shades inside the wall cavity—allowing them to disappear into the wall while not in use. Diminished R-value in the location of the retraction boxes was equalized by Peak-supplied vacuum insulated panels (VIPs) from Porextherm. Windows, blinds and shade boxes were coordinated through Peak—taking the guess work out of measuring and engineering. Peak Building Products also provided the ventilation equipment and made the connection with its engineers—allowing for the creation of an integrated mechanical concept to minimize equipment cost and controls. Last but not least, our client was extremely involved in the project—both from an engineering perspective, as well as during construction.


Key Features

  • Passive House design, performance and passive solar design in a cold climate
  • Masswall construction with ICF walls
  • Very airtight building envelope (0.28 ACH50)
  • German-made, triple-pane Passive House windows with insulated frames
  • Exterior motorized shading devices
  • Ground-source heat pump for heating and cooling, ventilation frost protection, post-conditioning and domestic hot water
  • “Building component activation” heating and cooling system
  • Commerical, balanced heat-recovery ventilation with ground-source pre-heater/chiller (earthtube)
  • PV-ready roof

Project Details

  • Design: Tim Delhey Eian
  • Mechanical: TE Studio, Ltd. & Lüfta GmbH and Client
  • Structural: Bunkers and Associates
  • Construction: Northfield Construction Co., Client and Tanner Construction
  • Project: 2012 – 2013

Photos

  • TE Studio (photos and renderings)
  • Client

Links

Passive House Database Entry