The Importance of Proper Heating, Air Conditioning, and Ventilation (HVAC) Design in Achieving an Energy Efficient and Comfortable Home

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1 The Importance of Proper Heating, Air Conditioning, and Ventilation (HVAC) Design in Achieving an Energy Efficient and Comfortable Home By Todd Synergy Airflow and Ventilation LLC I am having a hard time believing that you can guarantee exceptional comfort and energy savings in my 3000 square foot home with a 2 ½ ton HVAC unit. Most homes of the same size are having multiple units with 6 tons or more installed in them. If it is really possible, why isn t everyone doing it? These exact words came from one of my HVAC design and consulting customers, an engineer, during a recent meeting with him and his wife discussing the construction of their new home they plan to spend the rest of their lives in. The answer as I see it is.. The majority of homes do not have Manual J load calculations performed on them. o An accurate Manual J load calculation takes time and requires a lot of information. I have spent the last two years learning how to perform the calculations with Right Suite Software and more importantly, how to ensure it actually works in field installations. Do you have the time and the desire to do it right or do you want to do it the way it s always been done? What if we can do it for the same price or only slightly more than you were going to spend for the extra tonnage? (See The True Cost of Energy Efficiency). o The International Residential Code requires Manual J load calculations but code officials don t enforce it. (See IRC). Recently at an inspector s roundtable meeting I asked local building code officials why Manual J load calculations requirements are not being enforced as stated in code. The answer was that it is the contractor s responsibility to turn it in to be filed. However, there is no one to turn it into and there is no file. There are mechanical inspections though, but what is inspected? Are oversized units inspected to confirm they are wired correctly? Are the undersized and constricted ducts inspected so that they are insulated and air-sealed properly? Can someone explain to me how we got to the point where we inspect to ensure that the wrong system is installed right? o Most people do not understand that oversized units use more energy and contribute to comfort issues and high moisture levels. Consumers tell us all the time that they added extra tonnage in order to make sure they had enough. It is extremely important to understand that it is more efficient and comfortable for a unit to run almost continuously than it is to start and stop frequently. (Bigger is Not Better). o HVAC contractors have never had an incentive to size a unit properly. Code requirements for properly sizing a unit are not enforced by code officials. Oversized units are often used to mask poor construction practices.

2 HVAC contractors that size properly are blamed for comfort issues in homes that result from construction quality defects beyond their control such as improper insulation and poor quality windows. Bonus rooms are prime examples of this problem. More tonnage means higher sales revenue. Many HVAC companies are primarily in the business of selling and installing equipment. Multiple units can be installed in the time it takes to design a new system, commission and balance a new system, or diagnose an existing system. Rules of thumb are used such as 500 square feet per ton and $1500 per ton. Some HVAC companies bid the system over the phone without even looking at the home. A 2000sf home = 4 tons. 4 tons X $1500 = $6000. Sometimes the HVAC contractor will give you a bigger one for the same price if they happen to have one in stock that they need to get rid of. I am amused at one local HVAC contractor that advertises inventory clearance sales. What s the chance that the customer receives the properly sized unit? o Some HVAC companies offer short form Manual J load calculations. This practice leads to inaccurate calculations, so why bother? For example, some HVAC contractors will use the same load calculation for the same home that is built multiple times. However, the orientation of the home can greatly affect the load calculation as well as the specific airflow required by each room. We often see calculations manipulated to match the tonnage of the unit the contractor intends to install. o In retrofit work, most consumers rarely plan for expenses related to HVAC replacement. When HVAC failure occurs, consumers want service restored as soon as possible and are rarely interested in waiting for load calculations and total system engineering. (See ACCA QI standards). o Consumers have been led to believe that a high efficiency, high SEER rated unit with the Energy Star sticker or the little yellow energy efficiency sticker ensures energy efficiency and comfort. (See SEER Facts). An oversized, high SEER rated unit isn t efficient despite how perfectly the installation looks. The unit is only part of the total system that includes the ductwork and many other parts. Consider the millions of dollars spent on rebates from the Federal Government on HVAC equipment rebates of up to $1500 for energy efficient units that aren t really efficient due to improper sizing and the lack of consideration for the system as a whole. o Airflow, temperature, pressure, and BTU s are invisible. In order to be properly pieced together, these system performance indicators must first be measured with specialized equipment and then carefully adjusted. To achieve high efficiency levels and comfort, the entire system must be Synergized by an independent company other than the HVAC contractor. o Demand an Air Conditioning Contractors of America (ACCA) approved Manual J load calculation. Demand the documentation and the input data that was used. Note that HVAC contractors that install HVAC systems without proper load calculations and proper design will be held responsible for non-performing systems. Google HVAC Liability. It is my opinion that this will soon become a big issue in homes advertised as energy efficient and green. Manual J load calculations are used with Manual S equipment selection guidelines to pick the proper equipment to satisfy the load. (See HVAC Checklist). o Understand the difference between single speed and variable speed units and why the static pressure rating of the fan motor is so important. (See Variable Speed Fans are Mandatory). o Understand speed tap adjustments on single speed units and dip switch settings on variable speed units. Most settings are never properly set. Many HVAC technicians are not even aware that they exist. o Understand the advantages of two-stage compressors over single stage. Many HVAC companies have never sold or installed a two stage compressor. o Understand the difference between latent and sensible cooling and the importance of moisture control and fresh air ventilation. o Understand that HVAC units are sized according to the cooling load. When using a heat pump, the difference between the heating load and the cooling load is made up by supplemental heat

3 sources such as electric heat strips or dual fuel systems. We recommend all-electric heat pumps over the use of gas furnaces. o Understand the advantages and disadvantages of zoning. o Understand the advantages and disadvantages of using a ductless mini-split, a zoned system, or a completely separate unit for bonus rooms. o Understand the importance of thermostat settings and occupant behavior required for optimal energy efficiency and comfort. The majority of homes do not have Manual D load calculations performed on them. Undersized, improperly designed duct systems contribute to high energy costs and comfort issues. (Improving the Efficiency of Your Duct System). The problem is further complicated due to the fact that many architects and home designers do not plan for the physical location of the outside unit, the air handler, or the duct system. Without proper planning and design, the ductwork gets crammed in wherever it can be fitted and this leads to many terrible installations. Furthermore, with careful planning the total effective length of the duct system can be reduced which increases airflow. We see systems that can never work properly due to the length of the duct system that result from improper planning. o Most homes have only a single undersized return and most bedrooms do not have returns/jumper ducts installed. Air that is supplied throughout the home by numerous supply ducts cannot be properly returned to the air handler to be reconditioned by one single undersized return duct that is oftentimes leaky. An unbalanced system creates interior pressure problems, especially when bedroom doors are closed. As the return struggles for air, unconditioned air is pulled in from leaks in the building envelope and the duct system and it brings moisture, mold, dust, insulation, radon, and other contaminates with it. Vented appliances can be backdrafted resulting in carbon monoxide issues. All-electric homes prevent most carbon monoxide issues. We recommend installing a high quality Carbon Monoxide monitor. We test the pressure differential between every bedroom and the main body of the home with the bedroom door closed to ensure the pressure differential is less than 3 Pascals. Static pressure is increased. Static pressure testing is the equivalent of checking your blood pressure when you go to the doctor. However, few contractors test for it. We recently tested a brand new well-constructed home with an HVAC system that had a static pressure reading of 1.25 Inches water column (IWC). The rated static pressure was.5 IWC. This is similar to having an approximate blood pressure of 300 over 200. In other words, the system is on the verge of a stroke. The flow hood showed that the 4 ton/1600 cubic feet per minute (cfm) system was only returning 636cfm. 636/1600 = 40% of the rated airflow. What happened to the other 964 cubic feet of air? The answer is that return leaks accounted for the remainder. In systems with single speed blowers, high static pressure means less air is delivered and comfort issues are created. Frozen coils often indicate this problem. In furnaces, low airflow leads to tripped high limit switches and elevated operating temperatures that can create fire hazards. In systems with variable speed fans, high static pressure causes the motor to ramp up and consume more energy. Ultimately, premature motor and compressor failure occurs. High efficiency filters oftentimes restrict airflow. In many cases, high efficiency filters actually decrease air quality by causing contaminants to be pulled into leaky systems. We often see expensive filtration systems on duct systems that are leaking badly that are sold by unscrupulous HVAC contractors. Use unrestrictive, inexpensive filters and change them regularly. Have your interior coil(s) cleaned periodically. Never operate it during construction because many of the new systems we test have coils coated with sheetrock dust and construction debris.

4 Make sure back-boxes are installed on the return side and transitions are installed on the supply side of the air handler. o Most homes have undersized and restricted ducts that lead to increased static pressure, lower airflow, and higher energy usage. Return grilles should be sized at 1 square inch of return grille per 2 cfm of return air. o Make sure flex-duct installation guidelines are followed. Properly installed flex-duct works well and is less expensive and less labor intensive than other ducting materials. However, the same factors that make it popular often lead to poor quality installations. Keep in mind that flex-duct does have a limited lifetime. o Make sure you have input as to the location of the individual supply registers and return grilles. Most HVAC companies have their technicians determine the placement of registers and grilles based on the ease of installation. o Most duct systems are not tested for leakage. Leaking supply ducts lead to a direct loss of capacity. Duct leakage outside of the conditioned space leads to depressurization of the home. Plumbing is tested for leaks. Why aren t ducts? Never use framing members as supply ducts. Make sure joints are sealed with mastic. Make sure the supply boots are sealed to the sheetrock. Leaking return ducts and air handlers lead to unconditioned air being pulled directly into the system. Unconditioned air reduces capacity. This air brings contaminants with it and overwhelms the system s dehumidification ability. Never use framing members as return ducts or plenums. Air sealing improperly designed duct systems like many utility and government programs recommend can cause increased static pressure. Never waste money on duct-cleaning services that do not include total duct design and renovation. o Ducts located in unconditioned areas allow major conduction gains and losses. In this particular clients home, moving the ducts from the vented attic to a closed crawlspace resulted in a decrease of cooling by 17,477 BTU s which is 1 ½ tons. Does it make sense to deliver cool air through ducts located in 130 to 140 degree attics? The decrease in heating is 11,814 BTU s which is approximately 1 ton. Does it make sense to deliver warm air through 30 degree attics? Why not deliver air through ducts located in a closed crawlspace at 63 to 70 degrees year round? Our design program can show you the energy savings from using particular construction techniques over others. Oversized heat pumps with ducts located outside of the conditioned space have a bad reputation. When the unit short-cycles, the warm air that remains in the cold duct system becomes cold. When the oversized unit cranks back up and blows out a large blast of cold air it is very uncomfortable. Understand that heat pumps are designed to run almost continuously and that consumer behavior concerning thermostat settings can greatly affect comfort as well as increase energy usage. We oftentimes see ducts installed in crawlspaces in contact with the ground which is a direct violation of code. Oftentimes they are filled with water and most often are the result of improper planning. We oftentimes see ducts installed in vented attics in contact with the rafters and/or decking that allows major heat conduction. o Many duct systems are installed without balancing dampers. The systems that are installed with balancing dampers are rarely air balanced. Even then, the contractor often uses their hands to judge the airflow instead of a precision flow-hood designed specifically for the job. Comfort cannot be achieved without air balancing. For example, we often witness interior bathrooms and closets that are getting a great deal more air than specifications call for. This leads to rooms that require more airflow such as the kitchen, den, and master suite from getting the required

5 air specifications call for. We begin with static pressure testing to confirm that the system is moving the designed airflow. We then air-balance the system to deliver and return the right amount of air at the right temperature. o Never install supply ducts or return ducts from the system serving the main body of a home into a garage or some other space. Supplying air to a garage or storm room is a total loss in capacity and creates internal pressure issues inside the home. The return side attempts to pull the air that is supplied to the garage from other unintended areas. Tight homes require fresh air ventilation. This is one of the most contentious issues between energy efficiency experts and old school HVAC contractors, builders, and inspectors. o For every bit of air that is exhausted from a home by clothes dryers, kitchen exhausts, bathroom exhausts, and combustion appliances, an equal amount of air must be brought in to the home. In older leaky homes, this replacement air comes from multiple areas as witnessed by the fact that most older homes are drafty. In tighter homes, replacement air has fewer leakage sites to be pulled from and this leads to the creation of interior pressure issues. o Without a specific fresh air ventilation intake, air is pulled from unintended areas such as the crawlspace and the attic. This air brings moisture, mold, radon, pesticides, insulation, dust, and other contaminants with it. o Studies show that 50% of the air in your home originates in your crawlspace. This is specifically why we concentrate on closed crawlspace construction techniques. Many of the problems we find in the homes we test originated from issues concerning the crawlspace. Moisture control Helps prevents hardwood floor cupping and warping. Helps prevent sagging and structural issues. Helps control mold and indoor air quality issues. Helps control insects, spiders, small animals, and snakes. o The elimination of interior pressure issues combined with passive radon venting reduces radon entry into the home. o Dusty homes are oftentimes the result of interior pressure problems. Blown attic insulation and dust is pulled in through ceiling penetrations such as improperly sealed recessed can lights and pull-down stairs. o Exhaust-only ventilation is not sufficient in today s tightly built homes. We are yet to test a home that has not had at least one improperly vented bathroom exhaust fan. Many are covered in insulation. Many that appear to be working properly are not exhausting close to the rated cfm. This leads to moisture build up inside of the home. o High powered kitchen exhaust systems remove as much as 1200cfm of air. 1200cfm x 15 minutes = 18,000 cubic feet of air that has to be replaced. What happens when there is a woodburning fireplace located near such an exhaust? Many times the chimney becomes the fresh air supply and combustion byproducts are pulled back down the chimney. The smell of wood burning when the heat is on is a common symptom of fireplace backdrafting. o Dryer vents are oftentimes improperly vented into the crawlspace or attic and this delivers moisture that can lead to mold growth and structural issues. Many times, vents that appear to be properly vented are clogged up. o Without fresh air ventilation, vented appliances will back-draft and spill carbon monoxide into the home. For example, what happens when a clothes dryer is installed in the same room as an atmospherically vented/b-vented water heater? The two appliances compete for air and the dryer almost always wins. o Most HVAC contractors will argue that fresh air ventilation brought directly into the return side of the HVAC system overloads the unit. Replacement air will always be pulled in bringing moisture and other contaminants with it. We actually design for fresh air ventilation in contrast to most HVAC contractors that leave it up to the house to decide where the air is coming from. Our Manual J load calculations include the load from the fresh air ventilation system. o In the fall and spring when temperatures are mild, the HVAC system rarely operates. This leads to stale air and high levels of interior moisture. This allows dust mites to thrive and creates

6 indoor air quality issues. (See Air Cycler.) We recommend the use of hygrothermometers that monitor the humidity and temperature of the crawlspace as well as the home. Commissioning of the systems. o HVAC systems are assembled on site from a number of different parts which provides installers numerous opportunities to make mistakes. Research shows that a high percentage of HVAC systems have major problems. o The Energy Star Homes Version 3 that takes affect 1/1/12 requires commissioning. o Refrigerant lines must be properly sized and evacuated. Many HVAC companies do not own evacuation devices so how are they performing this mandatory procedure? o Airflow must be confirmed before the unit can be properly charged. In most instances, charging is taking place despite the lack of airflow verification. o Most HVAC companies do not own digital gauges in order to check refrigerant levels. Most own inaccurate analog gauges and rarely use them properly. o The condensate must be properly drained away from the foundation. o The thermostat must be installed correctly and you need to understand how to operate it. o Get all of the appropriate paperwork including installation manuals, operation guidelines, and sizing documentation. o Ask about maintenance and warranty contracts. o Demand that temperature diagnostics be performed. Most energy efficient programs focus on high R-values, high SEER rated units, duct-sealing, and energy efficient appliances. These are great starting points but the entire Synergy of the home must be considered. (Problems in Energy Efficient Homes). We design the system by taking the entire Synergy of the home into account. Read the The Seven Steps of Building a Synergy Home. For example, adding attic insulation without first air-sealing ceiling penetrations is almost always a waste of money. So is replacing windows because the return on investment is rarely ever achieved. We witness customers everyday that have spent thousands of dollars with little if anything to show for it. We perform energy audits with specialized equipment as opposed to basic visual inspections provided by the EnergyRight program. We then provide you with a comprehensive report that outlines the necessary steps needed to make your home energy efficient, comfortable, healthy, and durable. Keep in mind that if we don t find significant issues, the testing is free! (wetestothersguess). We recommend economical products and systems with high tolerance levels. We strongly recommend against products with low tolerance levels such as house-vented/vent-free fireplaces. We practice cost-shifting and recommend efficient products that actually help pay for other amenities. We offer scopes of work, as well as bidding services for insulation installation and HVAC installation. We confirm that bids are apples to apples not apples to oranges. We then inspect and enforce proper installation. The proper sizing, design, installation, and air-balancing of HVAC units provide a huge opportunity to reduce energy costs, increase performance and comfort levels, increase equipment life, and decrease warranty issues. Proper load calculations, duct design, installation, and air balancing more than pays for itself. Contact us to see an actual HVAC design including the Manual J, Manual S, and Manual D calculations. Contact us for testimonials from our customers. Check us out on Facebook at Synergy Airflow and Ventilation LLC.