Green Builder Program Technical Seminar
"Designing Homes to Accommodate Better HVAC Systems"
Wednesday, April 30, 1997
11:45 a.m. -1:15 p.m.
Time Out For Burgers
3201 Bee Caves Rd.
Speaker: Michael Sher, architect, former builder and owner of All Year Heating and Cooling
Call 499-3541 and leave a message to R.S.V.P.
The series will provide detailed instruction and interactive exercises on how to make your buildings environmentally responsive and responsible.
Cost for each seminar is just $15. All classes meet from 9 a.m. to 4 p.m. at the Thompson Conference Center on the University of Texas Campus at 26th and Red River Sts., directly north of the LBJ Library. Free parking is available and lunch is "on-your-own" and is available at the Thompson Center cafeteria.
These seminars are coordinated by the Center for Maximum Potential Building Systems, and are sponsored by the Texas State Energy Conservation Office, University of Texas Office of the President, and University of Texas School of Architecture.
For registration information, contact Gail Vittori at (512) 928-4786.
We have just begun a new print advertising campaign with the goal of educating consumers about green building products. Our goal is to have the consumers understand the value of choosing "green" materials and have the confidence to ask you, our members, to include them in their next home. We also have a regular column in the Sunday Home Section of the Austin American-Statesman called "The Green Builder." Articles on topics such as environmentally-friendly paint, Xeriscaping, and choosing a green builder have already appeared.
Remember, we have camera-ready logos to include in your advertising; we can also provide these on disk if you give us a little notice. This is another great way to separate yourself from the pack. If you would like more information on our marketing efforts, or have ideas for articles, call Jill Mayfield at 499-3545.
Which tapes and mastics for duct system connections will meet the 1993 Model Energy Code?
In Austin, duct sealing materials must meet the Underwriters Laboratory (UL) 181, 181A or 181B performance standards. These standards address tensile strength, peel and sheer adhesion, longevity and burning characteristics.
To meet the 1993 Model Energy Code, the City of Austin requires that at least UL 181 duct sealing materials be used ( 181A and 181B are acceptable) and must meet the following conditions:
The Green Builder Program requires that all duct closures be made using a non-toxic, latex water-based mastic with the UL181B-M or UL 181A-M (see table) approval. Mastics provide a greater assurance of an airtight seal. Mastic is very forgiving and will work even if the surface is a little dirty, wet, greasy, or the installer doesn't have his squeegee handy to press all of the wrinkles out of the tape.
For an inspection to go smoothly the inspectors must be able to see the UL listing mark, and the specific air duct closure system for which it is approved (e.g., UL 181B-M, UL 181B-FX) printed clearly along the length of all tapes, and on all buckets of mastic. This makes it easy for the inspector to verify that the correct closure system is being used for each duct type.
If you have any questions regarding duct sealing standards, call Doug Garrett at the City of Austin Green Builder Program, 499-3505, or Carl Meuth at the City's Residential Code Review section of the Development Review and Inspection Department, at 499-1856.
When my wife Jacky and I decided to purchase a new mechanical system for our 13-year old home in Round Rock, we were particularly concerned about getting a system which would dehumidify the house, as well as heat and cool it efficiently. Everyone knows that high humidity makes you feel even hotter when the weather is hot, but we knew that high humidity can influence health as well.
When relative humidity is above 70%- a common occurrence in Central Texas- molds, mildews and dust mites flourish, causing allergic reactions in many people. Jacky is one of them, suffering from unpleasant sinus and nasal congestion. This problem is especially bothersome in spring and fall, when it's not warm enough to turn on the air conditioning or cool enough to turn on the heat, either of which would lower the relative humidity and reduce biological growths within the house.
To alleviate Jacky's distress, I invented a system that I call TXEN. It combines a conventional high-efficiency air conditioner with an existing water heater, to prevent the relative humidity in the house from exceeding 70%. This is accomplished by circulating indoor air through the air conditioner, which cools and dries it, in response to a humidistat located in the house. However, before delivering air to the house, TXEN also heats the air to improve dehumidification and comfort. This might sound a little crazy, but the heat source is inexpensive hot water pumped from a natural gas-fired water heater to a coil located in the discharge air ductwork of the air handler.
I found the cost of my system to be lower than other heating, cooling, and dehumidification systems I investigated. My plumber modified the hot water piping of my existing water heater, and connected it to a hot water coil installed in the discharge ductwork of a new fan coil unit, replacing my old furnace. As planned, the new fan coil unit and hot water coil assembly fit neatly in the closet space vacated by my now-retired furnace. Furthermore, my air conditioning contractor mounted the new fan coil unit on top of a high-efficiency air filter (a 6-inch pleated-media type), supported by the old furnace pedestal, and used the opening in the pedestal, for return air just like in the old system. The cost of my installation was only $320 more than if my old furnace had been replaced with a new one because the fan coil unit and water heater were located close together.
A new home can reap the same benefits from this system at a lower cost. One piece of equipment, the water heater, does two jobs: it provides hot water and space heating with simple, off-the-shelf technology. The installation cost is reduced because you eliminate the furnace and the necessary gas and vent flue piping.
It is important to note that the water heater must be sized to meet the heating load of the house. A 50- gallon tank is usually sufficient for both water and space heating in Austin. In addition, the recovery-efficiency of the water heater should be 85% to ensure an adequate supply of space heat. Although such an efficient water heater costs more up front, it will be cheaper to operate than a less efficient one. It should also have a longer life due to the recirculating hot water aspect of the design, which reduces mineral build-up.
The overriding objective of the TXEN system is to improve comfort and health through continuous humidity control. However achieving this control will require additional energy use in the course of the year, since the air conditioner and water heater will operate at times that heating and cooling would not otherwise be used. By choosing efficient components, one can keep energy use and operating costs to a minimum. PECSD and the CES will be conducting field tests on my house in the coming year to monitor energy use and the cost of operation.
Our understanding of the need to control relative humidity in our work and living spaces has grown in the past few years. Doing it effectively is not a simple matter, however. For example, when we remove warm moist air from baths, laundries and kitchens with exhaust fans, we upset the pressure balance and pull in more outside air through the building shell. In Austin that usually means warm, moist air--just what we were trying to get rid of! I cannot stress too strongly the importance of viewing a home as a system, with materials and equipment interacting with indoor and outdoor air at varying temperature, humidity and pressure. Mechanical contractors who understand these interactions will be the most successful ones in the future, as customer concerns about family health and expectations for comfort continue to rise. If you have further questions about this system, call John Peterson at (512) 499-3569.
The goal of the program is to show that incorporating sustainable practices is good for their bottom line and good for Austin. The BEST Awards program will also publish and keep on file case studies and bottom line results from each winner. These case studies will help other businesses wanting to incorporate sustainable building practices.
There are two categories of awards, the Innovation Awards and the Success Award. The Innovation Awards are for businesses with significant and unique achievements in one of the following areas: energy efficiency, waste management, air quality, water quality and conservation, and land use. The Success Award is an award that recognizes overall achievement in all of the above areas. Special consideration is given to the businesses that have enhanced the surrounding community through outreach or involvement.
The BEST Awards Program is sponsored by the Austin Business Journal, the Association of Energy Engineers, the Hill Country Foundation, and the City of Austin. For an application, call Sue Barnett at 499-2458.
Gray concrete not your style? Today, finished concrete floors can be stamped to look like stone, tile or brick. They can be scored in a variety of geometric patterns. And, they can be just about any color or combination of color you desire. Color can be added at several different points in the process. Dye can be added to the concrete mix at the plant; it can be added to the surface and mixed in to the top layer of concrete while it is still soft; or it can be added at the end of the process through painting or acid etching.
If you suffer from allergies or asthma and are planning to build a new home, consider finished concrete floors. Carpets hold dust, dust mites, mold, and other allergens. Additionally, carpets and vinyl may be installed with glues and adhesives that give off irritating fumes. Cleaning a concrete floor is also very easy- it requires no harsh chemicals, only a broom and wet mop.
Because your foundation is in direct contact with the earth (which is an average temperature of 68 degrees in Central Texas), it can help the energy performance of your home. If you are worried about a concrete floor being cooler in the winter, place rugs in desired areas. While if may feel colder, its constant temperature helps in both heating and cooling your home.
If you are concerned about the hardness of a concrete floor, remember that tile is just as hard and that other types of flooring are applied directly to the foundation. Well-placed throw rugs in areas where you stand a lot will provide an adequate cushion.
The cost of a finished concrete floor can vary greatly. It depends on the types of patterns you include and how the color is applied. While you may pay more up front, this type of floor is so durable-unlike carpet and vinyl flooring-you will never need to replace it.
Several homes in the 1996 Austin Parade of Homes had finished concrete floors, and some homes in the 1997 Austin Parade of Homes in the Uplands this summer will also have them. If you haven't seen a finished concrete floor yet, this will be a good opportunity for you to see just how beautiful they can be.
If you are interested in this type of flooring, talk with your builder, or call the City of Austin Green Builder Program for more information.
Editor: Jill Manlove Mayfield
Green Builder Staff
The City of Austin is committed to compliance with the Americans with Disabilities Act. This publication is available in alternative formats. Please call 499-2501 for information.
Planning, Environmental and Conservation Services Department
206 East 9th Street
Austin, Texas 78701