HVAC Design Requirements in the International Building Codes

first_imgBuilding codes, especially those related to energy efficiency, have improved a lot over the years. With building enclosures, this has made a big difference. We now have more insulation, less thermal bridging, and tested air barriers. On the mechanical side, the improvements are significant — reduced duct leakage and mechanical ventilation in airtight homes — but there’s still a gap between some code requirements and what’s being installed.But that gap isn’t my focus today. Instead I’ll spell out what those HVAC design requirements are. But first, let me say a little about how building codes work. At the highest level are the model codes. The major player in this arena is the International Code Council (ICC), and I’ll focus on two of their codes that include HVAC design requirements for homes: the International Residential Code (IRC) and the International Energy Conservation Code (IECC). Of course, when you build a home, you’ll have to meet the requirements of your local building department, which probably uses one of the I-codes, perhaps with some modifications.On the topic of HVAC design, the IRC has more detail than the IECC, as you might expect. Also, the IECC just repeats some of the major requirements from the IRC.Equipment sizingBoth the IRC and the IECC say the same thing here:Equipment sizing and efficiency rating (Mandatory). Heating and cooling equipment shall be sized in accordance with ACCA Manual S based on building loads calculated in accordance with ACCA Manual J or other approved heating and cooling calculation methodologies. New or replacement heating and cooling equipment shall have an efficiency rating equal to or greater than the minimum required by federal law for the geographic location where the equipment is installed.That’s section N1103.7 in the IRC and R403.7 in the IECC, and it’s exactly the same in both the 2015 and 2018 codes. The main alternative to the ACCA Manual J load calculation protocol would be to use the ASHRAE Handbook of Fundamentals.In plain English, this requirement simply means that heating and cooling systems in homes have to be sized according to approved protocols. That’s Manual J from the Air Conditioning Contractors of America (ACCA) for calculating the heating and cooling loads of the house and Manual S, also from ACCA, for determining the capacity of the equipment needed to meet those loads. (A little reminder: Loads and capacity are different things. The former tells you what the building needs; the latter tells you what the equipment supplies.)Duct designGetting the home’s heating and cooling loads (Manual J) are the first step. Figuring out what equipment capacity to use (Manual S) is the second step. Some contractors go that far and then revert to rules of thumb for one of the most critical steps: designing the distribution system. If you’re going with an air distribution system (as opposed to hydronic), getting the proper air flow is critical. Here’s what the IRC says:M1601.1 Duct design. Duct systems serving heating, cooling and ventilation equipment shall be installed in accordance with the provisions of this section and ACCA Manual D, the appliance manufacturer’s installation instructions or other approved methods.This is the same in both the 2015 and 2018 versions. I wrote a multi-part explanation of the Manual D process last year, explaining how the available static pressure, total effective length, and friction rate determine the duct sizes you need to use to get the right air flow.The IRC has a lot of other requirements for duct design, too. For example, it allows the use of stud or joist cavities in walls and floors to be used for return air but not supply air (M1601.1.1). And it’s forbidden to supply conditioned air to a garage using the same system that supplies conditioned air to the living spaces (M1601.6). (That last one is a big no-no that can easily contaminate the indoor air with pollutants from the garage or carbon monoxide created by backdrafting a water heater.)Whole-house mechanical ventilationAirtight homes need mechanical ventilation. Building scientists have known this for a long time. Now it’s in the building codes. I don’t know when it first showed up, but it’s been in the IRC at least since 2012. Here’s how it’s stated in the 2018 IRC:R303.4 Mechanical ventilation. Where the air infiltration rate of a dwelling unit is 5 air changes per hour or less where tested with a blower door at a pressure of 0.2 inch w.c (50 Pa) in accordance with Section N1102.4.1.2, the dwelling unit shall be provided with whole-house mechanical ventilation in accordance with Section M1505.4.Georgia has been subject to this requirement for several years now, ever since we went on the 2012 IRC. We also require homes to have an airtightness of less than 7 ACH50. That means some builders have been aiming for what they see as the “sweet spot” of less than 7 ACH50 but greater than 5 ACH50. They meet both the IRC and IECC requirements for Georgia that way and aren’t required to add mechanical ventilation. (We’re still on the 2009 IECC here.)The good news for whole-house ventilation afficionados is that the airtightness requirements in the 2015 and 2018 IECC eliminate that “sweet spot.” The maximum air leakage allowed in IECC climate zones 1 and 2 is 5 ACH50 and in climate zones 3 through 8 is 3 ACH50. (That’s in section R402.4.1.2 of the 2015 & 2018 IECC.)Sections N1103.6 and M1505 in the IRC have some other requirements for ventilation, too. Here are a few highlights:Mechanical ventilation fans have to meet minimum efficacy levels in cfm/watt. (N1103.6.1)If the air handler is the main fan for the whole-house ventilation system, the blower has to be powered by and electronically-commutated motor. (N1103.6.1)The ventilation rate required in the 2018 IRC is calculated by the familiar equation:  Rate = (0.01 x conditioned floor area) + [7.5 x (number of bedrooms +1)]. That’s the basic equation from the 2010 version of the ASHRAE 62.2 standard. (M1505.4.3)Getting into the code is the first step…These things are a good first step. But there are a couple of other critical steps that have to follow. First, the IRC and IECC have to be adopted by states and local jurisdictions. I’ve been involved in the push to get Georgia to move to the 2015 IECC, and it’s not a fun process. We spent almost a year working through the issues, compromising on some of the items, and then getting the whole thing delayed another two years.And second, there’s enforcement. Building code officials have their hands full, and the majority of them don’t have the time or the resources to learn what they need to know to understand the reports they get. Some don’t bother with Manual J, S, and D reports at all. Some put forth a good effort but don’t know enough about what to look for in the reports.Once they get adopted into the local codes and building officials start enforcing them, HVAC design requirements in the code are kind of like locks on doors. They won’t keep criminals out. They’re just there to guide the honest folks in the industry. My hope is that we’re going to get to a point where the pressure to do things the right way will break through the activation barrier. That pressure is coming from a number of directions: the Internet, building codes, and green building programs, especially. Allison Bailes of Decatur, Georgia, is a speaker, writer, building science consultant, and the author of the Energy Vanguard Blog. You can follow him on Twitter at @EnergyVanguard.last_img read more

Hot Holiday Video Production Deals

first_imgHot Holiday Video Production Deals: LensesSigma 17-50mm f/2.8 EX DC OS HSM Zoom Lens: $369 ($669)B&H is cutting $300 from the price of the Sigma 17-50mm f/2.8 lens for DSLRs. The quiet autofocus is one of the standout features of this great piece of glass.Rokinon T1.5 Cine Lens Bundle: $1,247 ($1,447)This Rokinon Lens Bundle features 24, 35, and 85mm lenses, all in one package. The aperture and focus scales are now on the side of the lenses, making the focus puller’s (or your) job much easier. As far EF-mount lenses go, these lenses are top notch and produce quite the image.Hot Holiday Video Production Deals: DronesWith the recent release of the Phantom 4, Phantom 4 Pro, Mavic, and Inspire 2 (and that’s not even mentioning the Kharma drama), it’s tougher than ever to choose the right drone for your lifestyle. Of course, knocking a few bucks off the price helps.Right now it looks like eBay might have the best deal on drones. With Black Friday approaching, the word is that the Phantom 4 will be listed for $899 instead of the usual $1499. And that’s just the tip of the rumor iceberg.DJI Phantom 4: $1,199 ($1,299)With the Mavic possibly backordered until February, you can take to the skies immediately with the Phantom 4 for $100 less than usual. Check out our full review of the Phantom 4 and why it’s definitely worth your consideration.Phantom 3: $499 ($799)This is the most basic version DJI currently has to offer — and even if you aren’t particularly that interested in owning a drone, the UAV’s low $500 price tag makes it a deal that’s tough to pass up.Hot Holiday Video Production Deals: AccessoriesTASCAM DR-40 4-Track Portable Digital Recorder: $149 ($179.99)Amazon and B&H are chopping prices on all kinds of TASCAM products, including the handy DR-40. If you’re in need of an external audio recorder or any minor accessories that go with audio recording, now’s the time to jump.Dell UltraSharp U2715H 27˝ Screen LED-Lit Monitor: $429.99 ($649.99)Video editors searching for a quality monitor at a decent price should take note of this 27˝ ultra-wide Dell monitor — now $200 cheaper.Davis & Sanford Magnum P343 Aluminum Tripod with Ball Head: $129.95 ($249.95)This tripod is a steal. The huge cut in price, combined with the device’s durability, make it a must-have this holiday season. Really, you can never have too many tripods on deck while in the field.Retailer SpecialsSome of the biggest names in the video space are offering up the goods for the holidays. On December 6th, Red Giant is offering 40% off of EVERYTHING. For ONE DAY ONLY. So don’t mess around. Plus, B&H is currently running all kinds of crazy sales on a rotating selection of video gear. Definitely worth checking out!If you’re looking for additional Black Friday/holiday-related deals, give these retailers a visit for good prices on filmmaking gear and on-set essentials:Home DepotLowesB&H Photo VideoAdoramaAmazonBest BuyTargeteBay Know of any other must-have holiday deals? Share in the comments below! The holidays are finally here! These great deals, discounts, and sales will make it easy to give the gift of essential video gear.Top image via DSLR BuzzGood news for anyone living the film and video life: Retailers are rolling out their end-of-the-year deals just as the holiday shopping season takes off. Whether its saving $100 on a new MacBook Pro or snagging a 64GB SD card for $5 less than usual, every little bit helps. Here are some of the better deals we found while browsing for holiday bargains.Hot Holiday Video Production Deals: CamerasPanasonic Lumix DMC-GH4 Mirrorless Micro Four Thirds Digital Camera: $1,197.99 ($1,497.99)One of the best Mirrorless cameras currently on the market, now’s the time to scoop up the GH4. Given the announcement of the upcoming GH5, the price will most likely stay around $1,100, so its never a bad idea to be ahead of the curve.Sony Alpha a7R II Mirrorless Digital Camera: $2798 ($3199)Serving as Sony’s top-tier camera, the a7R is perfect for everything — the photos look stunning, and the videos look professional. With its full-frame CMOS sensor, this E-mount camera is versatile enough for videographers both in the field and in the studio.Canon EOS 5D Mark III DSLR Camera: $2,499 ($2,799)Canon’s cutting prices up and down its DSLR lineup, so there’s never been a better time to add the timeless Mark III to your arsenal. Already got one? Here are a few other Canon DSLR deals you might like.Canon 80D Bundle: $1,399 ($1,799)Canon Rebel T5 Bundle: $449Canon 70D: $899 ($1199)last_img read more

U.P. deploys ambulances for cows

first_imgUttar Pradesh Deputy Chief Minister Keshav Prasad Maurya on Monday flagged off an ambulance service that would cater to cows. Under the ‘Gauvansh Chikitsa Mobile Vans’ service, the ambulance would rescue ill or injured cows and transport them to ‘gau shalas’ or take them for treatment to the veterinary doctor. A “gau seva toll-free number” was also released so that common people can come to the help of such cows. A veterinarian will be present in the ambulance along with an assistant.Mr. Maurya, who posted pictures of the event on his Facebook page, flagged off five such ambulances from his official residence in Lucknow.In its initial phase, the service will be first available in Lucknow, Gorakhpur, Varanasi, Mathura and Allahabad. The ambulance service is being run in collaboration with the MNREGA Mazdoor Kalyan Sanghathan, an organisation that says it works for labourers and others employed in the informal sector. Its president Sanjay Rai said the organisation has a presence in five states.According to the brochure released by Mr. Rai, his organisation plans to take action against those people who abandon their cows once they stop giving milk, and also against municipality officials if cows are forced to eat polythene or plastic items dumped on the streets. A similar project was a few days ago reported in Khargone district of Madhya Pradesh, which is also ruled by the BJP. In 2015, 10 such cow ambulances were also deployed for service by an industrialist-cum-social worker.last_img read more