|
|
Blogs are supposed to be captivating – I mean, let’s face it, you’re basically reading someone else’s online journal or hearing them rant about their own personal interests. With that said , if it wasn’t captivating, then you wouldn’t read it. I am going to try my hardest to keep you captivated, but the reality is that this blog is on the exiting topic of…(get ready!)…diagnostic equipment for home performance professionals! Specifically, I will be discussing all the things that I DIDN’T know about the equipment or that I assumed incorrectly about how they operate. I have decided to write this because I recently spent some time reading the operation manuals for the equipment that we use regularly and there are some things that could possibly help other professionals make the best use of their equipment. I will say that the information in this blog is just stuff that I have found new to me about the equipment types we use, and is my interpretation of the operation manual language. If anyone would like to add to, dispute, or as questions, please comment!
Minneapolis Blower Door 
· Model 3 and Model 4 have six different flow capacities from fan open to ring E (I didn’t even know any rings beyond B existed). The total actual flow on the Model 3 can range from 6,300CFM to 11 CFM, with each ring having its own sub-range. Note that the DG-700 is capable of interpolating (or extrapolating) results that fall outside of this range based on pressure attained. Minneapolis recommends that the user installs the smallest flow ring applicable for accurate readings and because it increases the velocity of the air passing over the motor which is crucial to prevent the motor from overheating.
· Since we use a DG-700 with a standard speed controller and cruise control, it was easy to forget about all of the other controlling devices that exist. For example, the DG-3 and APT (Automated Performance Testing) are two common control devices. While I have never used it, the APT is connected to a software program called TECTITE that can perform various building tightness test while logging real-time results. This is very useful when conducting a multi-point test which, according to Minneapolis, are more accurate than one-point tests.
· The Model 3 has reversible fan flow, but accurate airflow can only be measured when air is leaving the exhaust side of the fan. Minneapolis does not recommend running the reverse function for long periods of time.
· Two main reasons we use ‘Depressurization CFM50′ as a standard is that back-draft dampers that are in place will be pulled shut (preventing inflated results) and any existing pressures (stack effect and wind) are mitigated due the high 50 Pa pressure induced by the fan
· Less than 1% error exists in the -45 to -55 Pa range (so fine-tuning to exactly -50Pa wastes time)
· The Minneapolis Leakage Ratio is a rarely used metric to quantify leakage. Expressed as CFM50/(Square Feet of Above Grade Surface Area)
· Discrepancies of up to 10% can be found in actual airflow due to differences in air densities at extreme weather conditions. Air density correction factors should be applied when applicable.
There is a wealth of other valuable information buried in the Minneapolis Blower Door Operation Manual. Notes on ventilation, costs associated with air leakage, and specific set-up procedures per testing type among them. I fully recommend sitting down and reading the manual for anyone who uses this device. The manual can be found here.
Retrotec Duct Blaster
· According to the Energy Conservatory, studies show that total house energy loss of up to 25% has been shown to be associated with duct leaks (yikes!)
· Retrotec recommends duct depressurization testing (as opposed to pressurization) because of the duct mask sealing the registers will be pulled tightly to create a tighter seal.
· Higher fan speeds lead to more accurate results (so install most restrictive slow ring that will still work)
· Field testing of the duct blaster is possible by cutting a hole in cardboard to a specified area, stretching the flex duct to full length, and depressurizing the flex duct WRT the ambient room and comparing the results with the calibration plate. For more specific instructions, see the link to the operation manual below.
· When placing the pressure probe into the supply register to measure duct pressure, location is key. Typically, leaky duct systems will have the lowest pressure at the furthest supply register. Therefore, placing your probe here will create a largely inflated leakage rate (since the fan will work harder to create the pressure specified). Placing your probe in the return duct or in the main supply plenum near to where the duct blaster is attached, would have the highest pressure and therefore an underestimated leakage rate. It is recommended for leaky systems that two measurements are taken in two different supply registers, and their results averaged. Tight duct systems have been found to have fairly uniform pressures.
· For testing ducts in unconditioned spaces, open the space to outdoors as much as possible to relieve any pressure buildup
· There are lots (and I mean lots) of ways that the Retrotec manometer can display leakage information (flow/area, EqLA, cfm, veleocity, etc…). I recommend finding out which metric you need for your test and setting up the manometer to display that information.
· Duct Basters can be used as a powered flow hood, and are not restrictive like traditional box flow hoods are
Again, there is an abundance of great information located in the operation manual for the Retrotec duct blaster. The manual, along with other guides for this device, can be found here.
 If you were to ask a random sample of residential contractors what the acronym RBEWHALCI meant to them, in true contractor fashion, they would probably be quick to come up with a clever answer that would sound convincing but far from anything remotely correct. If you asked a home performance contractor the same question, a percentage of them may know the correct answer, but I would be willing to guess that the larger majority STILL just treat the acronym like a cryptic set of scrambled letters. So, what does RBEWHALCI stand for anyway? Well, a Residential Building Envelope – Whole House Air Leakage Control Installer is a rare breed of BPI certified professionals that specifically deal with air leakage in existing homes. So even in the home performance contracting field, why is this type of professional rarely heard of? For starters, it is a relatively new designation for BPI, but the real truth in the answer stems from statistics: ONLY 3% OF ALL BPI CERTIFIED PROFESSIONALS HAVE THIS DESIGNATION! In my personal opinion, this designation covers some of the most fundamental and absolutely crucial aspects of home performance. As any home performance professional will tell you, air leakage is a major problem in the millions of existing homes in the US. According to RESNET, “Having your home properly air sealed is critical to your energy conservation efforts and greatly impacts your utility bills. You can save up to 30% of your energy costs by sealing multiple points of your home where energy losses occur.” These simple air sealing measures is what can turn a century old home into a comfortable, healthy, and sustainable dwelling.
Without digging to deep into the subject, I will briefly discuss a few concepts that home performance professionals concern themselves with on a daily basis. First and foremost, the never-ending physical phenomenon that leads to most of the comfort, moisture, and energy problems in a home is called the stack effect. In short, this concept describes the pressure imbalances in a building and how it
 Pressure patterns within homes relates to air leakage. For our climate, most of the year our upper-levels are warmer, and therefore highly pressurized when compared to our low-levels or basements. That being said, warm air is wanting to escape the top portion of our house while drawing in cold air from the bottom of the house to replace it. Other critical concepts that home performance professionals deal with are air flow and pressure, moisture, indoor air quality, and heat flow. Now, take a break from reading this for just one moment and think of several ways these components relate to air leakage and can affect one another. Truth is, they are all interconnected and therefore all work together to have our homes behave in ways we don’t want them to. So how do we cure this?
Well, firstly, a comprehensive and thorough home performance assessment will pinpoint the exact locations where air leakage is the most substantial. From there, an exact technique and methodology can be applied to the home where air leakage is a problem. How can we be assured that the home will actually be air sealed as prescribed? This is where you can be confident that the you have chosen a skilled, competent, and knowledgeable contractor because they are BPI certified as a RBEWHALCI. These contractors have been exposed to and worked with all of the most common bypasses in walls and attics and have proven that the materials and techniques used to correct the problem are safe and effective. A common and simple example of this is a recessed can light encased in a air tight drywall box. Additionally, students that take the course also learn to use a densepack insulating technique that combines insulation in walls (or other closed cavities) with air sealing. Because the demand for these professionals is increasing and there are so few of them in the workforce, the RBEWHALCI designation is a clear way to stand out from your competition. Simply letting the homeowner know that insulating is not the same as air sealing may be a concept that is entirely new to them and something your competition may not even understand.
With well over a million homes in the United States in need of various energy efficiency measures, it’s time to develop a strong workforce of individuals who are capable of completing this monumental task. Additionally, home owners need to realize that there are many benefits involving comfort, safety, energy efficiency, and if the home is to ever be sold, it will stand out in comparison to most other homes potential buyers will come across. As concerns about climate change continue to develop and energy cost become more expensive, professionals like Residential Building Envelope – Whole House Air Leakage Control Installers will become an invaluable asset to the home performance workforce.
As conversations about the price of oil and energy consumption rates find themselves in news stories across the globe, people are slowly beginning to question what they can do to minimize their carbon footprint. For most, simple strategies such as driving less or turning off lights are easy to incorporate into their current lifestyles. For others, larger investments such as home improvements that provide long term environmental benefits are a way to reduce consumption habits and create a comfortable, healthy, living space. Recently, Green Dream Group was called upon to validate certain criteria for a home owner that has long term goals of meeting strict Passive House standards (http://www.passivehouse.us/passiveHouse/PHIUSHome.html). As a young professional who is interested in all things sustainable, I frequently find myself encountering construction methods, techniques, and concepts that I have only read about or seen pictures of. In this specific case, the home owner decided to build the house using Structural Insulated Panels, or SIPs for short. Since the basis of my education as a civil engineer was focused on the structural aspect of building design, I was immediately fascinated with SIPs and was excited to see how they performed in the Midwestern climate. While I am no expert on the subject, I am going to take some time to introduce SIPs and explain some of the benefits and drawbacks to using them in residential construction.
SIPs are essentially a construction material that combines insulation with structural framing. However, in contrast to traditional framing, there is very little (if any) dimensional lumber used in a house composed of SIPs. This is achieved by sandwiching a thick, rigid, foam board between two structural boards. While there are multiple types of foam board and structural boards that can be used to create SIPs, it is very common practice to use polystyrene (extruded or expanded) foam as the insulation and oriented strand board (OSB) as the structural board. This method of construction has been in development since the 1930’s; however, it has taken decades for the practice to enter main stream residential construction. SIPs are very practical for residential construction; but due to the size and scope of most commercial projects they are limited when considering commercial application.
There are many aspects of SIPs that are attractive to someone looking to build a high performance home. Just by the nature of the material, SIPs are great insulators and air sealers. When looking from an energy efficiency or green building perspective, insulation and air sealing are two key items that must be addressed upfront. Because of this, the sizing of the heating and cooling equipment can be reduced when compared to a stick frame house of the same size. This will allow the owner to consume less energy and enjoy lower operating cost for the life of the building. Since these panels are fabricated off-site in a controlled manufacturing facility, there is a great deal of quality control that leads to tight-fitting connections with faster construction times. Again, home owner savings can be realized from the reduced labor required to construct the home. When looking at the sustainable benefits of building a SIP home, it is apparent why SIPs are admired in the green building world. First off, there is much less construction waste sent to landfills. Some estimates say that about 3-5 pounds of construction waste are generated per square foot of a typical residential building! Since SIPs are prefabricated, they are merely set into place once they arrive on site. Additionally, the panels use much less raw timber than a stick framed home which relieves our over-stressed forests. And as mentioned before, SIP homes are more energy efficient and therefore will use less fossil fuel in its life cycle. For more information on SIPs, visit the Structural Insulated Panel Association (http://www.sips.org/).
Despite all the benefits gained from building with SIPs, there are some limitations that would prevent someone from choosing SIPs for their home. Generally, the upfront cost of the home is higher than that of a standard stick framed home. This is because of a combination of many factors that are usually tied to the specialty contractors, designers, and equipment (such as cranes) involved in the construction of a SIP house. However, various sources indicate that the extra money spent upfront can generally be recovered through expedited construction schedules and lower operating costs. When considering sustainable disadvantages, the owner should be conscious of the foam material and binder in the OSB and choose products that don’t off gas any harmful compounds. Another distinct drawback to SIPs is that the embodied energy is generally much higher when compared to wall sections made of other materials.
Going back to the experience I had with the SIP home that was aiming for passive house standards, there were a few things that surprised me after I was able to explore the house. First, for some reason I expected the home to have a different look to it – almost as if it was going to apparent that it was a SIP house just by looking at it. While there were subtle indicators, overall the house appeared to look as normal as any other home I had been in. Something else that I thought was fascinating was that the air and thermal barrier extended from the subgrade basement to the attic roof since the roof was also composed of sips. Generally, in my experiences as an energy audit technician, I have yet to see a house with such a well defined and sealed envelope that extended into the attic. Once we began the blower door test, I was amazed at the results. While the house was not quite Passive House ready, it was only a few hundred CFM; much lower than any result I had ever seen. When investigating to find the main sources of the air leakage, we discovered that it primarily composed of numerous small leakage areas once we had closed the heat recovery ventilator.
I would like to learn more information on SIPs as I continue to work in the home performance industry. Mostly, I am curious to know how the panels are connected to ensure air tightness. Also, since OSB is a structural element, it must be kept dry otherwise the material loses its ability to handle any axial load. Are there additional water barriers to ensure that the OSB remains dry? Lastly, I am curious to see how electricians and plumbers perform their work with the SIPs in place. I imagine that it’s pretty tough to work with a prefabricated panel even if there are chases drilled through the foam…Thanks for reading and feel free to comment!
It’s that time of year again!
Tax season is once again upon us, and with it brings the search for money-saving deductions. While some deductions may be a reach, Chicago Home Performance helps homeowners secure a write-off that will pay off three-fold; making an improvement in the energy efficiency of your home could not only qualify you for the Nonbusiness Energy Property tax credit, but – along with a Comprehensive Home Energy Assessment from Chicago Home Performance – will also help make your home more comfortable and save you money on your utility bills.
The Nonbusiness Energy Property Federal tax credit provides homeowners with a tax credit of 10% of the cost up to $500 of making improvements to the taxpayer’s primary residence*. Eligible improvements include improving insulation, replacing heating, cooling, or water heating equipment, and upgrading old, inefficient windows. This incentive is in addition to others that homeowners can receive from local governments and utilities.
The incentive amount of 10% applies to the 2011 tax-cycle; if you made any of the qualified improvements listed above in 2010, the incentive amount is an impressive 30%, or up to $1500.
Chicago Home Performance provides homeowners with all the information they need in order to make their homes more comfortable and save them the most money. Our trained staff has audited hundreds of homes like yours, and through our comprehensive inspection and diagnostics process, we recommend a list of improvements that is tailored specifically to your home.
This year, the groundhog’s shadow was buried by the blizzard, so don’t wait out the long winter to find out how Chicago Home Performance can help improve your home. Book with us today!
*Tax Credit does NOT include installation costs.
Although the new home construction market has been tempered by our nation’s recent economic condition, more homes than ever are being built to energy efficiency standards.
According to the Environmental Protection Agency (EPA) ENERGY STAR website, 23% of all new homes constructed in 2010 earned the ENERGY STAR Qualified New Homes label. This number is up from 21% in 2009, 17% in 2008, and 12% in 2007.
Chicago Home Performance is part of the movement to help new home owners and builders achieve energy efficiency program certification. As a third-party verifier organization, we perform the necessary inspections, testing, and energy modeling to confirm that the home meets the required efficiency standards, so that new home owners have piece of mind that their new home will be safe, comfortable, and efficient.
To qualify for the current Version 2 iteration of the EPA ENERGY STAR New Homes program, a home must achieve a 15% reduction in energy use against the 2004 International Energy Conservation Code (IECC). Beginning in July 2011, the energy efficiency thresholds to meet the new Version 2.5 ENERGY STAR New Homes program will become more stringent, with homes needing to exceed the efficiency requirements of the 2009 IECC.
In addition to increasing the energy efficiency requirements of ENERGY STAR New Homes, the revamped program also includes criteria for quality design and installation of heating, ventilation and air conditioning (HVAC) equipment, enhanced indoor air quality, and improved building durability.
Whether you’re a consumer who is considering having a new home constructed, or a homebuilder looking to get ahead of the curve, Chicago Home Performance has the knowledge and experience to help your energy efficient new homes project meet its goals.
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
today to see how we can help.
|
