Rizzieri Custom Residence
(Merlin’s Lookout)

  • Client: Natalie Bryant-Rizzieri & Aaron Rizzieri

  • Contractor: Bristlecone Builders, Inc.

  • Location: Hart Prairie, Flagstaff, AZ

  • Type: Home
  •  Size: 1,589 SF Livable Space + 683 SF Unheated Utility

  •  Cost: Approximately $320,000

  •  Schedule: Design: 11/2019-08/2020, Construction: 03/2021 – Current

  •  Features: ICF walls, Efficient thermal envelope, Off-grid features include: Passive Solar Heating, PV Electrical, Natural Daylighting, Water Tank Storage, & Rainwater Harvesting

New custom off-the-grid 3-bedroom 2-bathroom single family residence in Hart Prairie.

0 Vision:
Merlin’s lookout is a compact 3-bedroom, 2-bathroom single family residence on a 1 acre parcel. The design accommodates a long list of needs and wants for this active family of four, while maintaining an economical shape for reduced construction cost. Being high up in the mountains at an elevation of almost 9,000 feet, this off-grid structure is built out of hearty materials for energy efficiency.

1 Context:
The residence is positioned to allow a smooth outdoor-to-indoor transition from the main entry on the North, the patio on the South, and the utility area on the West, all at different levels. The building is cut into the side of the naturally-sloping grade to make use of the geothermal mass for the unheated lower storage and utility area. The house runs East to West, working with the natural site drainage and solar gain. The building’s location and size proportions were based off of existing tree locations to utilize the available sun and to supply privacy. The house is close to a prized ancient Bristlecone Pine to the West, as well as the existing tree house in the large tree to the East.

2 Function
The building program includes three bedrooms, two bathrooms, kitchen, dining, living, entry/mudroom, and an unheated utility and storage area. The lower utility space has snowmobile & gear storage, solar equipment, and two 5,000 gallon water storage tanks. Up the stairs bring you to the main entry and mudroom. Through the mudroom is the main public area with an open living and dining room, as well as the kitchen around the corner. The bedroom level sits just a few steps above the main floor for added separation and privacy.

3 Aesthetics
The owners wanted the house to nestle into the surrounding land and not dominate it. The modest shape & height of the house allows the surrounding trees to be the centers of attention. A neutral color palette helps blend the house into the natural landscape, and the interior has warm wood-finished and bronze tones. Window placement was thoughtful and abundant, especially on the South side to allow lots of natural light into the spaces. Level separations allow the house to be as short as possible minimizing stairs, while keeping the heavier-used areas more open and inviting.

4 Construction
Balancing passive maintenance, exterior aesthetic, and construction cost, the overall building footprint is a simple rectangle that is tiered into the sloping site to balance cut and fill. The South-facing pop-out was a calculated design choice to allow for the maximum direct sunlight for passive heating. The design also balanced the interior around the horizontal shift to allow for easy ICF forming, concrete slab construction, and floor truss installation throughout. Even though the floor levels change, the roof line purposefully remains constant throughout to keep the truss package minimal.

5 Details
The roof trusses provide an 18″ energy heel to provide a full thermal envelope for the sealed house. While the design is dedicated to keeping the structure extremely energy efficient, many details were added to customize the house to the particular owner’s needs, including extra space for a bedroom reading nook, and living room has floor-to-ceiling built-in bookshelves along the North wall.

6 Materials
The owner decided on durable ICF walls, to keep the interior extra-insulated, and an exterior stucco finish. A steep 6:12 sloped metal roof allows for easy snow shed and rainwater harvesting. The need for large openings for natural ventilation and connection to nature guided the selection of metal clad wood casement windows and a large patio slider double door. The main level floor is a finished slab-on-grade to act as a thermal mass to passively heat the home.

7 Structure
Since the house endures harsh winter conditions, the building foundation was over-designed to be extra-sturdy. ICF walls have a concrete core of 8″ on the lower level and 6″ on the floor above. The floors of the storage level and main floor are slab-on-grade, and the upper bedroom floor is I-Joist framed. A durable metal roof covers the energy-heel wood truss roof framing. The largest openings were placed on non-weight-bearing walls to minimize structural members.

8 Systems
The South-facing glass was chosen to have a low U-value, with a high Solar Heat Gain Coefficient to keep the glazing energy efficient while also allowing the rays to warm up the concrete thermal mass when needed. To maximize efficiency, the traditional furnace, ducting, and on-demand water heater are located completely inside the heated envelope. A central wood-stove provides an additional heat source.
Harvested rainwater and potable water are stored in two 5,000 gallon tanks that sit in a lowered section of the storage area. Keeping the tanks accessible allows the family to monitor the water levels and clean as necessary.
Being an off-grid residence, the house relies on a photovoltaic system for its energy, but also has a propane generator backup. Abundant daylighting decreases the need for artificial light, but when needed, LEDs provide an efficient source.