The healthy house concept is an idea that has been requested by people with various environmental illnesses for many years. The aim is for the house to be built so that a very minimum of construction chemicals, especially formaldehyde based adhesives and pesticide treatments, migrate into the house to affect the people living there.

 

This subject is now becoming more and more of a concern for everyone in our society with buildings being built more tightly for energy efficiency and also with increasingly sophisticated medical research that is demonstrating physiological harms of the type that can lead to such health problems as asthma, from extremely small concentrations of formaldehyde based materials, or studies that are showing multigenerational genetic damage from pesticide injuries.

 

This article briefly describes a house that was built with both healthy house considerations and total environmental efficiency in mind. And upon evaluation, it merited an Energy Star rating of 95 or Five Stars Plus.

 

The location is in the mountains west of Denver, Colorado in an aspen and conifer forest. The elevation is 9,000 feet (2745 m). The degree-day climate rating for the area is 9,300 degree-days (5150 Celsius degree-days). (Compared with a value of some 6000 (3300) for Denver.) There are occasional windstorms with winds as much as 100 miles per hour (160 kph) in the area so the design must accommodate that fact.

 

Fire safety is a serious concern for this building area. Many of the local hillsides are very steep (30 ... 60 degree slopes) and covered with dense conifer growth that would spread a fire very rapidly. To address this concern, trees were drastically thinned to some 200 feet (60 m) upwind of the house site for a defensible fire space. Additional fire protection is provided with a 36-inch (92 cm) weed barrier cloth installed around the outside of the house and weighted down with rocks.

 

Another fire safety consideration that is needed for this area is an 1,800 gallon (6800 liter) water storage tank that was installed near the house. This tank must be kept filled with water, which is not available for domestic use, but must be available so in case of a fire, a fire truck can use that water to foam down the house and hopefully prevent serious damage.

 

The building site is some 1,000 feet (300 m) from the public power lines, so local photovoltaic power was cheaper. This in turn made power efficiency - both house and appliances - very important. Which in turn led to a house design that maximized passive solar gain. This mandated a sizeable southern exposure in addition to a very well insulated house with very low infiltration.

 

A passive solar design requires a long house east to west and narrow north to south. The result was a house with a floor footprint of 48 feet (14.6 m) east to west and 24 feet (7.3 m) north to south. To accomplish reasonable solar gain, the south windows are 5.9% of the floor area with a solar gain coefficient of 0.70, the east windows are 1.5% of the floor area, the west windows are 1.8% of the floor area, and the north windows are 3.4% of the floor area.

 

The typical summer temperature at the building site is around 65 degrees (18 degrees C). As such, maximum solar gain is desirable, even in the summer. To meet this need, the south roof overhang was adjusted back to six inches (15 cm) instead of the usual 24 inches (61 cm).

 

The roof and ceiling were made with pre-engineered solid lumber scissor trusses (carefully sealed off from the living area) that give an outside roof slope of 6 in 12 and an inside ceiling slope of 3 in 12 for a semi-cathedral ceiling. The roofing is SBS Rubber/Fiberglass shingles that have a Class A fire rating and are approved by some insurance companies as having adequate hail resistance to qualify for a reduction in house insurance cost.

 

For reasonable passive solar performance, a massive floor that can store heat is needed. This resulted in the following floor from bottom to top -

• compacted native soil.
• dry sand, four inches
• radon barrier
• foam insulation, four inches (10 cm)
• concrete slab, four inches (10 cm) thick

One square foot (0.093 square meter) ceramic floor tiles were installed on top of the concrete for a living space floor.

 

A further benefit of the slab on grade design and not needing any heating ductwork is that there is no need for a crawl space under the floor to accumulate mold and the other problems that cause so much grief. (Plumbing lines were pre-installed before the floor concrete was poured.)

 

To maximize passive solar heat gain, the concept of "tuned windows" was used, where windows with different heat gains and insulation values were used on different orientations. The windows on the south side were selected for high solar transmission, with a transmission coefficient of 0.70. The other windows were selected for high insulation, with a thermal resistance of 9.10 Ft**2-F-Hr/BTU. This results in an anticipated solar gain of over 50 percent of the needed building heat coming from the sun.

 

A very important healthy house consideration is to minimize the presence of pesticides and formaldehyde based building chemicals leaking in the living space. (Hopefully for the duration that the house is habitable!) The following wall construction was used - from outside to inside, the wall consists of -

• pressed cementitious siding for fire protection.
• sheet plastic building wrap for infiltration control,
• oriented strand construction board for structural strength,
• polyisocynanate insulation panels,
• 2 by 6 (5.1 by 15.2 cm)solid lumber studs with 2 (5,1 by 10.2 cm)by 4 interior cross-strapping.
• cellulose insulation (with only borate treatment for insect control),
• 6-mil sheet plastic to seal out building chemicals and control infiltration,
• 1/2 (1.3 cm) inch regular plaster board sealed with hypoallergenic "mud,"

The wall was then finished off inside with a low volatile organic compound interior paint. This results in a very well insulated and low infiltration wall rated for 110 miles per hour (176 kph) that causes no obvious problems.

 

Given this design, a heat source of 40,000 btu per hour input, which after the loss in efficiency for this elevation, is adequate to keep the house comfortable down to some -30 degrees Fahrenheit (-34 degrees C) outside temperature. A sealed combustion 40,000 BTU per hour input fireplace was installed in the living room to heat the house. There is no ductwork, either below the floor or over the ceiling, to distribute heat to the rest of the house; air circulation and floor conduction are adequate.

 

A house with a low infiltration rating must have means of allowing fresh air into the house and means of exhausting stale or contaminated air. To this end, manually operated 5-inch (12.7 cm) inlet vents were installed in the east and west walls. A 70 cubic feet per minute, outside exhausted, bathroom exhaust fan was installed in the bathroom. A standard range hood exhaust fan, again outside exhausted, was installed in the kitchen.

 

An attached garage 24 by 24 feet (7.3 by 7.3 m) was very well sealed off from the house with 5/8 inch (1.6 cm) fire-rated drywall and both infiltration and fire barriers. The door to the garage from the house is a tight fitting 1 3/8 (3.5 cm) insulated steel door. The outside garage door is an insulated and tight fitting 1 3/4 inches (4.5 cm) thick unit.

 

An interesting feature of off-grid photovoltaic systems, in the context of environmental illness is worth mentioning. Normal operation of the system is for sunlight to generate power in the photovoltaic panels which is stored in several large 1200 ampere-hour batteries at 24 volts direct current. An inverter takes the 24 volts DC and transforms it into 120 volt AC power for the house.

 

A mode is available so that when the amount of 120 volt AC house power being used drops below a certain point, such as a couple watts, the inverter is turned off (to conserve power). A test pulse is sent to the house every couple seconds or so to see if someone has turned on an appliance, in which case the inverter comes back on line for normal 120 volt AC power. By carefully managing the house electrical loads, and using DC powered appliances, such as refrigerator and freezer, it is possible for the 120 volt AC power into the house to be automatically off much of the time except when really needed. People with EHS who have visited reported they felt much better when the AC power turned itself off.

 

The result is a house with the following characteristics -

• Energy Star Rating of 95, Five Star Plus.
• House footprint - 24 by 48 feet.
• Garage footprint - 24 by 24 feet.
• Wall insulation > R30.
• Ceiling insulation > R60.
• Floor insulation > R25.
• Building infiltration < 0.07 air changes per hour. (Typical houses range from 0.35 to 0.50 air changes per hour.)
• South windows - R3.2, solar gain coefficient of 0.70.
• Other windows - R9.1, solar gain coefficient of 0.31.
• Floor - insulated solid 4 inch concrete slab on grade, no crawl space.
• Design Climate Efficiency -
  • 3196.87 Btu/degree-day = Heating Index of 2.77 BTU/DD/Ft**2 of floor. (Typical "energy efficient" homes are some three times this value.)
• Observed Heating Efficiency -
  • 2005 - Heating Index = 4.17 BTU/DD/Ft**2 of floor
  • 2006 - Heating Index = 2.59 BTU/DD/Ft**2 of floor
  • 2007 - Heating Index = 2.46 BTU/DD/Ft**2 of floor
  • 2008 - Heating Index = 1.96 BTU/DD/Ft**2 of floor
  • 2009 - Heating Index = 1.88 BTU/DD/Ft**2 of floor
• Electricity - local off grid photovoltaic system -

  Twelve 115 watt photovoltaic panels

  60 ampere photovoltaic power controller

  Eight 6 volt, 1200 ampere-hour batteries

  A 2000 watt 24 volt DC to 120 volt AC inverter

  • Total Power Collected by Photovoltaic System in 2005 - 1,076 Kilowatt-hours.
  • Total Power Collected by Photovoltaic System in 2006 - 1,253 Kilowatt-hours.
  • Total Power Collected by Photovoltaic System in 2007 - 1,293 Kilowatt-hours.
  • Total Power Collected by Photovoltaic System in 2008 - 1.526 Kilowatt-hours.
  • Total Power Collected by Photovoltaic System in 2009 - 1,584 Kilowatt-hours.
• House heat source - 40,000 BTU input rated sealed combustion propane fireplace.
• Water source - local well, with efficient AC or DC powered pump.
  • The water pump requires some 32 watt hours of electricity to fill and pressurize a 60 gallon water tank.
  • Hot water - sealed combustion tankless water heater.
  • Bathroom and Kitchen fans - exhausted outside with tight backflow covers.
  • Telephone - buried solid conductor cable from County road area.
  • Refrigeration - DC powered refrigerator directly connected to the photovoltaic system batteries. Rated at 77 watt-hours per day.
  • Freezer - DC powered unit directly connected to the photovoltaic system batteries. Rated at 272 watt-hours per day.
  • Energy Star Estimated Heating and Hot Water Cost - $342.44/year
  • Nearest neighbor - 1/2 mile (0.8 km) away.

 

The big question is "does it work?" The owner has sensitivities to pesticides, tobacco smoke, perfumes, and several building chemicals. He has lived in the house for over a year with no problems caused by the house.

Additional information about the Sawmill House -

• Bighorn Builders Inc.; http://www.bighornbuildersinc.com/

    Gallery

      Sawmill House

•  
• Boulder Green Building Guild; http://www.bgbg.org/

    Library

        Boulder Grren Building Journal

          Winter 2007 Journal issue

          Clean Mountain Living, by Larry Kinney

•  
• Conservation Center -
• http://conservationcenter.org/assets/upload/Sawmill-House.pdf
•  
•  
• Owner's Summaries of Performance

Solar Living Source Book, Eleventh Edition

Complete Guide to Renewable Energy and Sustainable Living

Publisher: Gaim Real Goods

Web: http://www.realgoods.com/

This is a large, 590 page, publication printed on 8 1/2 by 11 sheets. It covers a wide and diverse variety of subjects including land and shelter, electrical energy, energy conservation, water systems and purification. Where appropriate, it includes practical applications of many items available from this company.

The Passive Solar House

Using Solar Design to Heat and Cool your Home

Author: James Katchadorian

ISBN 0-930031-97-0

Publisher: Chelsea Green, 1997

Web: http://www.chelseagreen.com/

This 210 page, 8 by 10 inch page, book provides detailed specifications for planning and designing a home which obtains much of its energy from passive solar heating. The details and support tables are presented for calculating how much solar gain can be expected for various design strategies.

The Passive Solar House

The Complete Guide to Heating and Cooling your Home

Author: James Katchadorian

ISBN 0-933392-03-7

Publisher: Chelsea Green, 2006

Web: http://www.chelseagreen.com/

This 224 page, 8 by 10 inch page, book is a revised and expanded version of the above book. A more detailed presentation is made of the author's Solar Slab heat exchanger technique and its application to using passive solar energy to provide much of the heating of a house. Details and support tables are again presented, in more detail, for calculating how much solar gain can be expected for various design strategies. The book also has extensive appendices of worksheets to design for the author's Solar Slab technique, Solar Intensity and Solar Gain factors, Thermal Properties of many building materials, Design Winter Temperatures for selected cities, Average monthly and yearly degree day values, and Mean Percentage of Possible Sunshine for selected cities.

The Weather Conditioned House

Author: Groff Conklin

Library of Congress: 58-7200

Publisher: Reinhold Publishing, 1958

This 238 page, 8 by 11 inch page, book covers many aspects of integrating housing design into fitting with the environment.

The Healthy House, Fourth Edition

Author: John Bower

ISBN 0-9637156-9-0

Publisher: Healthy House Institute, 2001

Web: http://www.hhinst.com/

This is a massive, 445 page, 26 chapter, compilation of information that covers in detail many of the Healthy House concepts. It is printed on 8 1/2 by 11 sheets and amounts to an encyclopedia of builder's information for remodeling or building a healthy house.

Homes that Heal and Those that Don't

Author: Athena Thompson

ISBN 0-86571-511-4

Publisher: New Society Publishers, 2004

P. O. Box 189

Gabriola Island, British Columbia, V0R 1X0

Tel: 800/567-6772

This book spells out the many significant differences between a conventional home and a healthfully built home. It includes a glossary of terminology, organizations, available newsletter, books and many products in this area.

Healthy Construction Guidelines

Edited by Christi Graham, Marc Richmond

ISBN 0-86571-511-4

Publisher: Healthy Homes Publications (undated)

180 Harbor Drive, #231

Sausalito, California, 94965

Tel: 888/388-5735

Web: http://www.healthyhomedesigns.com/

This some 50 page looseleaf book gives an explanation of the health risks from many conventional materials. It provides many detailed recommendations of non-toxic alternatives, contact information for manufacturers, and distributors. It provides a step by step guide for building or remodeling a safe, healthy and non toxic home.

Prescriptions for a Healthy House

Authors: Paula Baker Laporte, Erica Elliot, John Banta

ISBN 0-86571-434-7

Publisher: New Society Publishers, 2001

P. O. Box 189

Gabriola Island, British Columbia, V0R 1X0

Tel: 800/567-6772

This book provides detailed specifications on requirements, site work, concrete, earth Masonry, alternatives to frame construction, metals, woods, plastics, thermal and moisture control, door and window openings, finishes, specialties such as pest management, water treatment, electrical and magnetic field management, and furnishings.

The Mold Warriors

Authors: Richie C. Shoemaker, James Schaller, Patti Schmidt

ISBN 0-9665535-3-5

Publisher: Gateway Press, 2005

1001 N. Calvert Street

Baltimore, MD, 21202-3897

Web: http://www.moldwarriors.com/

This book is a report on recent developments diagnosing, and treating toxic mold caused human illness. The author presents diagnostic protocols and treatments that claim to accurately diagnose and treat biotoxin caused illness. The book presents many examples of contaminated building and their effects on people. And sad to say, the book has examples of the resistance many public health and legal authorities raised to findings of mold contamination. Also presented are summaries of several precedent-setting legal cases in this area. The book also presents a summary of what is considered a Safe or Healthy House.