Building Scientist Geeks stop speaking Geekese!
November 20, 2010
I was part of a guided bus tour of Urban Infill, Affordable EarthCraft Virginia projects at the Virginia Governors Conference on Housing in Richmond, Virginia last week. One of the tour guides, a young man who I have a great deal of respect for, stated in explaining the EarthCraft philosophy, “That we(EarthCraft) are all Building Scientist Geeks.” Of course I mouthed back, “Speak for yourself.”
It was strange, because the young man who made the statement, original involvement in the field was working for a small volume builder. He had hands on experience, but like many in this evolving “Green” Sustainable, Energy Efficiency building movement, admitted that he is evolving into a building scientist geek.
What does that have to do with anything? Who cares? Well I care and so does the mass majority of people in the United States. Why do I say the vast majority? Without the vast majority of consumers buying into sustainability and efficiency efforts, the movement will remain at the fringe of society’s concerns. Yes, it will continue to be embraced by Engineering, Architectural and Building Scientist Geeks speaking Geekese amongst themselves about the importance of what they are doing and why, but the good old average American, just living life, will go on as usual until emergencies force them to do something. I don’t blame them.
What is the consumer to believe. They are inundated with an overload of Green information on the web, the newspapers, TV, radio, etc. There is so much technical information out there, that it takes people involved in the business hours daily to stay up. Do any of us actually believe consumers are going to try and stay up with all this techno information? Do any of us really believe that the consumer cares one iota if vapor contained in an air mass penetrates the exterior shell of a building? Come on. They care about what the net result is to their life, their business, or their budget, not the technical mumbo, jumbo or “Geekese.”
Green to most consumers, whether they be building owners, home owners, developers, business owners has to do with the biggest Green in the world–the Green dollar. Most people, contrary to what may be said verbally, do not make a decision based on saving the planet. They make a decision based on dollars. Those dollars have to have a return on investment, usually shown in lower utility costs, lower tax rates, tax credits, lower operational and maintenance costs, longer longevity, and more residual value at the end of a time period. If it doesn’t make economic sense, it isn’t going to get done.
Now maybe the Gates, Buffets, Pitts, Jobs, and DeCaprio’s of the world have the dollars to expend on saving the planet and taking it Green. But the rest of us, we have to watch how we spend money and we aren’t into spending it foolishly. Most of us are not interested in having bragging rights at a cocktail party filled with raised pinky martini drinkers over who has the best solar system. We go to work, we provide, we come home and we live life. We control what we can. If someone can show us how to save energy, that will make it easier for us to cover our monthly expense nut, we can buy into that, but we aren’t buying into what happens 10 years from now, we have to live today.
If we don’t start explaining this sustainable effort in common sense, value terms, this avalanche of the Green movement, might just disappear, excepting that which is written into Building Codes, when this recession/depression ends. If we don’t start explaining to people that commons sense sustainability and energy efficiency makes economic sense and they can see it in the results, our efforts will go the way of the energy revolution of the early 80′s.
HVAC Renovation Duct Leakage
September 18, 2010
Duct Leakage Concerns:
The following is a revision based on an actual report concerning duct leakage in a multi-family Low Income Housing Tax Credit Renovation being done to EarthCraft Virginia Standards:
One of the areas of most concern is the return grill area being installed when the Air Handler is put in place. At the same time as the return plenum is being installed, the return grill is being put in place, making it hard to see what is being sealed between this metal plenum and the framing surrounding it.
The only unit I could see the installation of the return plenum without the grill in place was in building number 000, unit #12. I am attaching a picture with this report. As seen the sheet metal return is not sealed. The other units where the air handlers were being installed already had the return grill in place. In looking at it from the Air Handler closet side there appeared to be no sealant in place.
In looking at the supply registers in the same buildings, where the registers had not been put in place, I could observe the sealing being applied. Unit #6 in Building 0000 had, it appeared, an expanding white sealant applied in Breakfast/dining area and looked to be the best sealing method I observed.
Here is the dilemma: The latest duct blaster testing on September 15 showed 103 CFM’s of total leakage. But it only showed 12 CFM’s of leakage to the outside of the envelope. This is 1.41 % leakage to the outside, substantially below the EarthCraft Virginia standard of 6% leakage to the outside of 51 CFM.
I don’t know which way to counsel a solution in this situation. The ductwork itself is being installed correctly to EarthCraft Standards. The problems are encountered with the final hook up to the air handler, the terminations of the supply boots/registers and the return grill.
The following is a little lengthy, but required to explore the issue.
Here’s what EarthCraft Standards say:
Required Air Sealing Measures
“Framed spaces that connect conditioned areas to unconditioned areas must be sealed with sheet material and sealant.” A diagram shows all HVAC penetrations being sealed that lead to unconditioned areas.
Ductwork/Air Handler
“Required: Duct Blaster test result <6cfm to outdoors per 100 Square Feet of floor area served.” Or 51 CFM in this case. The units tested are substantially below this requirement.
Duct Seams and Air Handler sealed with Mastic:
“All transverse seams in supply and return ducts, including supply and return plenums and leakage sites in the air handler, shall be sealed with duct mastic and fibrous reinforcing mesh according to SMACNA specifications. Duct tape is not suitable sealant for ducts, but may be used for sealing leakage sites at the air handler’s removable access panels and at filter access panels.” A diagram shows caulk between drywall and boot in sheetrocked, insulated ceilings.
The entire HVAC system is inside the thermal envelope in these buildings now being tested. The results of leakage to the outside are substantially lower than EarthCraft Standards—a good thing. In order to improve the overall duct leakage substantially then improvements have to be made in the sealing of the Air Handler, the return plenum and supply terminations located in the sheetrock, hardwood floors and bath floor finishes.
In the ceiling terminations many builders use caulk or a compression strip on the boot, so that the sheetrock is installed with this sealing in place. Where existing hardwood floors are in place, usually found in renovations, sealing these terminations is not as straight forward as new construction processes. In new construction, there is a subfloor allowing a boot termination to overlap the subfloor between the hardwood and other finish floor, such as carpet, linoleum, vinyl. This boot termination is sealed to the subfloor.
In the hardwood and bath terminations of Project X, the supply boot is terminated at floor level, with no overlap, leaving a gap between the supply boot and the floor. It is not practical to install a mastically sealed boot overlap on the hardwood floor. That leaves the issue of how best to seal. It has to be something that not only seals, but can expand and contract with heat and cooling cycles. Some contractors use tape that overlaps the floor that can be covered by the finish supply register.
The termination of the Return Plenum is another story. This leakage is within a couple feet of the Air Handler. Its termination attachment to the framing is a big concern. It has been my experience over the past 3 years that return terminations can be haphazardly sealed, after all it is only a return, seems to be inherent in many contractors thinking. Unfortunately return leakage causes pressure imbalances and the unit looks to make up the difference from other unfiltered sources.
This attachment is not affected by any differences between new construction and renovation techniques. When this area isn’t sealed effectively, it is the source of major leakage. The return grill is immediately put on with the setting of the air handler and extension of the sheet metal return duct making it impossible to inspect the termination without removing the grill. The few grills I have removed have shown issues with the termination. The one I saw this week with the sheet metal installed and no register in place, showed no sealing(see attached picture), now maybe this is being done, but is there anyway to hold off the installer from putting that grill in place until the termination seal with the framing is inspected by the supervisors or EarthCraft? This makes a lot more common sense then testing, finding leakage and then having to remove it. Many installers use mastic and tape to seal this properly.
It might help the high total duct leakage results if the Air Handler itself was taped and sealed along the edges. I see this done quite frequently. The concern with some contractors is warranties. It might also be advantageous to seal the access panel with duct tape and mastic and tape around the edges where the return meets the Air Handler in places where just bare metal exists.
Yes, this is longwinded, but the sealing of all these areas was of concern to xxx when he was on site. It certainly would help the overall leakage and reduce duct leakage to the outside. Real efforts are being made to correct the issue. I have met with the HVAC contractor and the job supervisors on this and they are making a substantial effort at solutions on the subsequent buildings, only future tests will show if they are making a difference. What is going on in the immediate area of the Air Handler and return is the ongoing concern. But as mentioned above, there are some issues with a renovation, it isn’t as straight forward as the system approach for new construction.
Manual J sizing for Single Family/Multi-Family HVAC Installations!
September 6, 2010
Over the past few years I have reviewed literally 100′s of Manual J calculations. For those not familiar with a Manual J calculation–in common sense terms–it is a program used to size the equipment used in the installation of the HVAC system for a particular home, townhouse, condominium or apartment. Every credible HVAC contractor should have one or access to one. It is not tricky. It is straight forward. It should be the 1st thing calculated when a dwelling unit’s thermal envelope specifications have been established. Isn’t it common sense to size the HVAC system based on the actual conditions that exist?
This following is not all inclusive, but it will give you an idea of what basic information is required to be input into a Manual J program.
Size of dwelling unit, volume of unit.
Orientation-North, South, East, West
Insulation: R value of walls, foundations, slabs, ceilings
Windows: Type, u-value, Solar Heat Gain Coefficient.
Infiltration: Air Changes per Hour, tightness of house.
Approximate Duct Leakage
Indoor Dry Bulb temperatures for winter and summer
There are more than a few other factors including Latitude, Elevation, and Temperature Range, but these parameters are not necessary for you to gain a basic understanding of the concept.
The Manual J is starting to be required in many locations for a building permit. Why is it important? Would you rather have your HVAC system based on a rule of thumb or actual field conditions? Me–If I was building or renovating a structure, especially one I am taking pains to make energy efficient, I want my HVAC based on reality.
Why am I going to build a Sustainable, Energy Efficient dwelling to Energy Star or another verifiable building program and then just have the HVAC contractor size it depending a rule of thumb based on a leaky, minimally insulated dwelling.
I am a Technical Representative for EarthCraft Virginia. When you get an EarthCraft certification, you also get an Energy Star certification. The critical issue in the process is energy efficiency. This means sizing the HVAC correctly and installing it correctly.
I know that when I look at a Manual J calculated for EarthCraft House in Virginia, where Air to Air Heat Pumps are prevalent, if I see a sizing that shows me less than 800 Square Feet per ton, that someone hasn’t inputted the correct data. An EarthCraft or an Energy Star certified house in my part of the world should be between 800-1200 Square Feet of Living Space per ton. That mean if I have a 1600 Square Foot House, the largest HVAC unit should be 2 tons. If I build it tight, then it should be 1.5 tons.
There are standardized inputs for the Manual J. An EarthCraft or Energy Star dwelling unit is not standard. What do I see the most of: Incorrect u values and solar heat gain coefficients(SHGC) for the windows. I see window inputs that do not even meet Energy Star requirements for the location, even though the contractor knows this has to meet Energy Star Thermal Envelope Standards and Energy Star Window specifications for the region.
I see someone who has taken the pain to upgrade their insulation, and yet standard insulation is specified in the Man J. I see infiltration numbers included that are totally excessive. I see duct leakage specified that does not meet Energy Star minimum standards.
I could go on and on. Bottom line: What is the result of all this? Usually an over-sized system, that does not operate efficiently in a supposed Energy Efficient dwelling. Oversizing of HVAC systems means the builder/homeowner/building owner spends more money for less efficiency. In my part of the world it also creates issues with mold, mildew, humidity problems and excessive heating and air conditioning bills. It also means that if my contractor specifies a 3 ton unit and it should be 2 tons if done right, I just spent easily a $1000 for an additional ton I didn’t need. How is that saving me money?
When you are building an energy efficient building, do yourself a favor, specify a manual J calculation and then look at the inputs. If you don’t know what you are looking at, find someone who can tell you. Putting in an HVAC system without proper sizing and input data is a waste of your time and money, whether you are a Home Owner, Builder, Developer or Building Owner. “Build it tight, and size it right.”