Gaddy House

Gaddy House

The vision for the house and surroundings was to build the most environmentally friendly and beautiful house possible in the most socially responsible way possible.

In more detail, the visions for the house were to:

  • Build an attractive solar powered residence that produced more energy than it consumed
  • Construct the house in a way that was friendly to the environment
  • Design the house to gracefully accommodate the aging of the owner
  • Be within walking distance of the owner’s place of employment
  • Landscape the property with native plants
  • Incorporate urban agriculture
  • Use no water from an outside source
  • Allow no excess water to flow off the property
  • Reduce the heat island effect
  • Design and build to insure clean interior air
  • Provide a maintenance free environment inside and out

The project was designed to meet the requirements of multiple green building rating systems, including

  • Passive House Institute of the United States (PHIUS)
  • LEED (Platinum rating)
  • Living Building Challenge

The house design and development was a collaborative effort between the owner, Ed Gaddy; the architect, Miche Booz; the builder, Taz Ezzat; the PHIUS consultant, Michael Hindle; the LBC consultant, Peter Doo; the energy consultants, David Peabody and Izumi Kitajima; and the natural landscape architects, Lauren Wheeler and Mary Sper. The design progressed with significant collaborative input from each of these principal contributors and others through numerous meetings and teleconferences.

Throughout the design phase, each of the stakeholders listed above provided input to the entire group and the group discussed this input. From this, the design of the house evolved to incorporate the challenging and sometimes contradictory concepts. The builder organized a plan to meet the design determined by the collaborators.

Vital Stats

Certification Status Net Zero Energy Certified
Version of LBC 2.1
Location Clarksville, MD
Typology Building
Project Area 53,143 sf
Gross Building Area House - 2,187.4 sf / Garage - 698.9 sf
Building Footprint House - 2,187.4 sf / Garage - 698.9 sf
Start of Construction May 2013
Start of Occupancy January 2014
Start of 12-month Performance Period August 2015
Owner Occupied Yes
Occupancy Type Residential
Number of Occupants 1-3

Project Team

Owner Edward Gaddy
Owner Representative Edward Gaddy
Project Director/Manager Edward Gaddy
Architect Miche Booz, Miche Booz Architect
Contractor Mautaz Ezzat, Maryland Custom Builders, Inc.
Mechanical Peter Neubauer, PE
Electrical Mautaz Ezzat, Maryland Custom Builders, Inc.
Plumbing Mautaz Ezzat, Maryland Custom Builders, Inc.
Lighting Design Miche Booz, Miche Booz Architect
Landscape Lauren Wheeler, Mary Sper, Natural Resources Design, Inc.
Structural Peter Neubauer, PE
Interior Design Miche Booz, Miche Booz Architect
Geotechnical Easterday Well and Pump
Civil Dean Packard, PE
LEED Consultant Janice Romanosky, Pando Alliance
Energy Consultant David Peabody, Peabody Architects
Passive House Consultant Michael Hindle, Passive to Positive
Living Building Challenge Consultant Peter Doo, Doo Consulting, LLC
Key Subcontractor (Framing) Bruce Jones
Photo Courtesy of Miche Booz Photo Courtesy of Miche Booz

01. Limits to Growth Imperative

The project is located in a neighborhood of single-family detached homes on approximately 1-acre lots. Nearby is the Johns Hopkins Applied Physics Lab Complex where the owner works as a spacecraft engineer. This facility is about a three-minute walk from the residence, which reduces car use and pleasantly increases the owner’s exercise.

While the house is not within easy walking distance of grocery stores, restaurants, barbershops, etc., it is certainly within bicycling distance. Sidewalks are available for most of the distance to these stores despite the rural residential zoning of the house itself.

The landscaping, which began in spring of 2016, will provide asparagus, numerous berry bushes, and fruit and nut trees. There is an existing cherry tree near the southeast corner of the garage and several walnut trees near the northwest corner of the lot. All of these food-bearing plants will be used as a basis for a healthy, local plant-based diet.


The team took steps to reduce the heat island effect by using highly reflective paving and roofing materials. The driveway and roof are light colored, which helps reflect incoming radiation.

Photo Courtesy of Jeff Wolfram Photo Courtesy of Jeff Wolfram

07. Net Zero Energy Imperative

Many factors were taken into consideration in the design and construction of this home:

  1. Site

The building is oriented to maximize winter solar heat gain while minimizing summer heat gain. Overhangs are designed to shield the summer sun while allowing the winter sun to penetrate the home.

  1. Passive Design

Overall, the house plan lays out a passive solar area along the south side. All of the triple pane windows and doors are designed to maximize winter heat gain and minimize winter heat loss. The building envelope, including the floor slab, is heavily insulated.

  1. Construction Systems & Details

Wall studs are 2×6 and are insulated with high-density fiberglass. Outside of the studs is the air barrier. Attached to the air barrier are 12” TJIs. The cavities between the TJIs are filled with insulation. Gaps in the air barrier are filled with Prosoco Joint and Seam Filler under a Prosoco Cat 5 air and waterproof barrier. Under slab insulation is EPS. The roof assemblies employ a combination of mineral wool and blown in fiberglass insulation. An insulating blanket is created by the addition of 2×10 framing to the roof. Minimum target R-values are: Floor R-34, Walls R-70 and Roof R-99. Windows are triple glazed fiberglass and have a good solar heat gain coefficient. A layer of foam glass between the stem wall and the footing eliminates thermal bridging.

  1. Air Tightness

A regiment of sealants, coatings and tapes are applied to all gaps or sheathing surfaces. The project is designed to achieve a maximum of .6 air changes per hour by blower door test.

  1. Ventilation

Cross ventilation is provided in all living spaces during the shoulder seasons. An energy recovery ventilator provides fresh air during the summer and winter extremes. Clerestories work for venting and facilitate airflow through the chimney effect. Overhangs around the entire project are calculated to protect from summer heat gain.

  1. Equipment and Appliances

The oven, dishwasher, refrigerator and clothes washer were selected for their energy and water efficiencies. The clothes dryer is vent-less with a heat pump. Cooking is accomplished on an induction cooktop. The primary heating systems are air-to-air mini-split heat pumps. All lighting is LED.

  1. Renewable Energy

A 1 kW solar thermal system provides domestic hot water and is supported by point of use proportional controlled electric water heaters. The solar electric system that connects to the grid is a 6 kW photovoltaic array.

Photo Courtesy of Jeff Wolfram Photo Courtesy of Jeff Wolfram


Early on, the owner and the builder set-up a meeting at the office of the Howard County Department of Inspections, Licenses, and Permits to request the use of air admittance valves for the plumbing vents to help avoid potential air leaks. The meeting was attended by several inspectors and the head of the department, Robert Frances. The inspectors effectively shut down the presentation that the owner had prepared more or less stating that the AAVs were not to code and that none had ever been allowed in Howard County. The owner believes this to be false as he has heard of several kitchen islands with sinks; these have to have an AAV to function properly. With one exception, the inspectors were generally hostile to the point of borderline rudeness (such as not listening to the presentation). One inspector did take an interest to the extent that he helped the owner design a plumbing venting system that would not vent through the roof.


The house is equipped with a heat recovery ventilator that connects to a vent hood over the cooktop. The vent-hood is designed to re-circulate air in the kitchen but has been modified to instead send air to the heat recovery ventilator. The vent-hood has excellent filtering and keeps smoke from reaching and contaminating the HRV and it also has a fan that throws grease to the side keeping it from reaching the HRV. The owner considers the use of the HRV in combination with the highly clean exhausting vent-hood to be an innovation.

Another innovation is the use of Foamglas under the footings of the house. The Foamglas provides an unusually strong insulator on which to place the footings.


The residence was designed to meet the then Passive House Requirement of 0.6 air changes per hour. Prior to fitting the house with insulation and wallboard, the house was tested with a blower door and it met the requirement. Unfortunately, the measurement was faulty, showing the house met the requirement when it actually did not. It would have been very easy to meet the requirement with some additional caulking of the air barrier had the deficiency been detected at this relatively early stage of construction. Unfortunately, the problem was detected only after the house was fully constructed. Subsequent to that reading, another incorrect measurement was taken showing that the house passed.

The incorrect measurement was detected after the fact by pictures taken by one of the architect’s assistants that show the blower door reading followed two minutes later showing that the manometer was set to the blower door configuration.

The lesson learned is that the blower door measurements can be tricky and may need to be repeated several times.

Photo Courtesy of Jeff Wolfram Photo Courtesy of Jeff Wolfram

18. Rights to Nature Imperative

The Equity Petal promotes equitable access to all people regardless of physical abilities, age or socioeconomic status. I18 Rights to Nature states that a project “may not block access to, nor diminish the quality of, fresh air, sunlight and natural waterways for any member of society or adjacent developments.” The Gaddy House does not hinder access to sunlight or fresh air for any of its neighbors, in part because it is more than 100 feet away from its closest neighbor, and the building itself is only one story with a maximum height of 16 feet. The project does not affect access to, or the quality of fresh air for others in the community because the home is all electric and has no emissions.

Photo Courtesy of Jeff Wolfram Photo Courtesy of Jeff Wolfram

19. Beauty + Spirit Imperative

The Gaddy House is a small single family dwelling that adheres to the Vitruvian architectural principles of Firmness, Commodity, and Delight. Its design is a genuine effort at all three attributes, but with regard to the last characteristic, it intends to elevate the spirit through beauty, striving to do so in several ways:


The designer uses geometry, in particular the square and multiples of squares as visual and conceptual motifs, to organize the plan, elevation, and interior. At the most basic level, the house is divided into two squares — one a public zone, the other a private zone. The elevations are composed using square windows and materials organized into shapes that consist of multiple squares. The interior, including the cabinets and porcelain tile, uses the same proportions based on multiples of the equilateral rectangle. To achieve harmony for the exterior of the structure the design relies on a three-dimensional composition using a limited, monochromatic palette of materials, unifying the four structures that are on the site.


The principle facades of all the structures use symmetry as a device to organize the vertical plane. This takes the form of local symmetry on the front elevation of the house. This elevation is divided in half, then further subdivided into symmetrical parts. As Sir Edwin Burke characterized beauty: “unity in variety and variety in unity.”


Pleasing three-dimensional composition depends in part on the previously mentioned attributes, but relies more on the relative masses of the overall design. Here, the effort created variety in height, bulk, diagonal elements and distribution of the structures. The relative arrangement of the programmatic parts strives for unity.


The house is sited in a verdant garden of suburban agriculture. Surrounded by Maryland’s lush local flora and edible horticulture, the house stands as a manmade object in contrast to its environment. Beauty can be most poignant where unlike elements successfully combine to form more than just the addition of several dissimilar parts. The interior is surprisingly colorful and varied in its use of materials. Stepping into the house provides an opportunity to sense the complementary color strategies as well as the combination of textures and surfaces.

As a tribute to the process, there is a “materials collage” installed on a wall, a large homage to the process of choosing the materials, colors, and their juxtaposition for the project.

20. Inspiration + Education Imperative

Old Hopkins Road has held more than five open houses over the past three years. The project has invited groups from the DC Living Building Challenge Collaborative, the American Institute of Architects, the Maryland Chapter of the US Green Building Council and visitors who attended Greenbuild 2015. Individual architects have even brought clients who are interested in pursuing the Living Building Challenge. Visitors, including neighbors, were given tours of the home and allowed to see all the equipment in operation. In 2015, Dr. Gaddy invited Sharon McCrae, an expert in Whole Food Plant Based Diets, to discuss how to effectively manage and use edible gardens.


The project team instituted measures to reduce rainwater runoff. The project took a variety of steps to ensure a highly permeable area. The entire roof directs rainwater to a rain garden, and the solar panel structure directs rain to a 1,500-gallon cistern.

The landscape attracted Monarch butterflies this past summer, which resulted in many Monarch caterpillars The owner is proud of this in view of the recent decline of the Monarch population. In part, this is attributed to the decreasing number of milkweed available for their reproduction. The milkweed is the only plant on which they will reproduce.

The progress of building and debugging the house is blogged at