System's Architect

Zman

NREL

Asking NREL is a good idea.

What you are calculating is such a variable target that at some point you are going to have to make a (hopefully highly) educated guess.

Obviously, storing the water at lower temps (higher volume) with more insulation is advantageous.

I find you work very interesting, keep us posted.



Carl

hot_rod

additional reading

Issue # 13 of Idronics would have some good Hydronic Cooling design info for you



http://www.caleffi.com/usa/en-us/technical-magazine



Uponor seems to be offering a lot of radiant and hydronic cooling training and case studies lately. Looks like one of the NREL senior engineers was involved with one of these projects. Always good to have a name when you contact them.



http://www.uponorpro.com/~/media/Extranet/Files/Heating%20Literature/RC_Bro_Trifold_RC04_10123.aspx?sc_lang=en



Review some of the info at www.healthyheating.com I know some of the engineers that hang there have done radiant cooling designs. More emphasis on IAQ and creature comfort in those discussions, as there should be.



Keep in mind there is a limit to how much professional design help you might expect to get for free



Most in this community generously share. Asking for a specific design which could take days or weeks to develop, might and should come with a price tag.

Rod Stucker

Research & Development Mode

I have read through and studied most of the pertinent Idronic series including volume 13. Wonderful publications along with the illustrations and schematics provided by Ziggy. Ziggy showed interest in assisting with this project at first, but he appears to be just too busy and not enough time in a day.



I am planning on working with a few graduate students including a mechanical engineer and architect with the help of some fellowship grants. We are still very much in an R&D mode, particularly in regards to how much energy we can conserve using an all concrete structure to routinely store and release thermal energy, something that has never been done to this scale.



Then we have structural engineering to fine tune and the potential to replace conventional rebar with steel microfiber and synthetic macrofiber. The steel fiber alone can eliminate much of the labor normally required to place rebar. The cost savings can then go to our multi-source HVAC system, programmable automated controls, and energy management system for showcasing at our ZNE-PHMH project. I am intrigued with validating the PCA modeling which reveals that the thermal mass of concrete can conserve up to 44% of heating energy, and 30% of cooling energy. This may allow us to proportionately reduce our mechanical requirements for solar thermal collectors, though not much help on reducing GSHP requirements once we drop below 2 tons on the heating side. The highest COP performance is achieved by operating a 100% variable GSHP at about 50% of capacity.

SWEI

Automated windows, shades and blinds

have come a long way in the past 30 years or so.  Prices are still fairly high -- north of $200 per operator last time I used them on a job.  With proper control they can really work wonders - opening first floor windows at night when the whole house fan turns on, directing evaporatively cooled air to specific rooms while keeping it out of others, and of course shading control.  Most run on small DC motors that only draw a few watts.  ECMs really make the most sense for high duty cycle applications like fans and pumps.

Rod Stucker

Minimizing Delta T & Optimizing Heat Transfer

In contrast to conventional wisdom which suggests using 3/8" or 1/2" radiant PEX, the potential for using 3/4" or 1" PEX to deliver more BTUs at lower temperatures (Lower Delta T) while increasing heat transfer and minimizing headloss (friction) is appealing. The above illustration (which I have once again inserted here), even though it is refers to tubing used in geothermal field loops, reveals the strategic advantages of using larger sized tubing to enhance flow rate and turbulence for 4 ft. of headloss per 100' of tubing.



For example, in conjunction with installing 6x6 steel mesh in a slab/ICF T-beam floor/ceiling, 3/4" or 1" PEX could easily be installed by almost anyone who can read a set of tubing installation plans by winding in on 18" centers, and winding back out in between tubes with periodic fastening of the PEX to the steel mesh with zip ties or steel wire, whatever is desirable.



Though conventional wisdom indicates that this investment in larger PEX tubing is overkill, that may not be the case when you evaluate the cost savings from minimizing Delta T and headloss while optimizing heat transfer. The key to optimizing heat transfer for a low Delta T (e.g., as little as 10 F for 70-80 F water in heating mode and 55-65 F water in cooling mode) would appear to be optimizing flow rate and turbulence. As indicated, the larger PEX tubing can provide a faster flow rate which enhances turbulence (there are also tube designs that can enhance turbulence with minimal increases in flow rate) without substantially increasing headloss. This is particularly true for strategic designs that incorporate shorter runs.



Simply by using 100% water systems with no heat exchangers in our system design except for DHW, we can increase the efficiency of heat transfer for our integrated HVAC system by 30% while minimizing headloss. As described above, the larger PEX tubing, faster flow rate, and relatively short circuits would further increase heat transfer while once again minimizing headloss. This should result in an appealing modified internal rate of return (MIRR).



As listed above, regarding heat transfer rate, the 3/4" tubing at 6.5 GPM results in a velocity of 3.6 fps, Nu = 141.23, h = 649, and a headloss of 7.74 ft/100'; 1" tubing at 6.5 GPM results in a velocity of 2.29 fps, Nu = 115, h = 422, and a headloss of 7.74 ft/100'; and 1" tubing at 8.0 GPM results in a velocity of 2.82 fps, Nu = 139.01, h = 510, and a headloss of 3.83 ft/100'. Notice there is over a 50% drop in headloss for using 1" tubing vs. 3/4" tubing.



Developing modeling and simulation software to optimize tubing size, spacing, and length of circuits for a targeted Delta T that provides an appealing MIRR appears to be another job for NREL's BEopt team

Rich_49

Throw Rugs

will NEVER not influence performance .  Since you are building this system why don't you consider getting out of the floor and going to the ceilings ? Never seen anyone put anything on a ceiling that can effect performance .  You could save lotsa money and not worry about rooms overheating by means of solar heat gain in a passive haus standard . You quite likely won't need half as much mechanical assistance either .

Gordy

Ceilings

Is the way to go like Rich stated. More responsive than concrete floors, plus radiant ceilings in cooling mode have a little more output than radiant floors. Use RFH in some select areas baths. Tight tube spacing a must.



Use of less conductive floor coverings with radiant ceilings will give a neutral effect to the bare feet.

Rod Stucker

Conserving Energy via High Thermal Mass Structures

I have submitted the following to BEopt in hopes of developing specific modeling and simulation categories and options for evaluating energy consumption of high thermal mass (ICF/concrete) structures:



According to the Portland Cement Association, houses built with ICF exterior walls require an estimated 44% less energy to heat and 32% less energy to cool than comparable stick-frame houses. A typical 2,000 square foot home in the center of the U.S. will save approximately $200 in heating costs each year and $65 in air conditioning each year. The bigger the house, the bigger the savings. In colder areas of the U.S. and Canada, heating savings will be more and cooling savings less. In hotter areas, heating savings will be less and cooling savings more.



In light of what can be achieved with exterior concrete walls, one can only imagine what could be achieved through construction of high thermal mass (ICF/concrete) structures including external and internal walls, floors and vaulted ceiling all constructed of concrete. When such air-tight super-insulated concrete structures are combined with radiant heating and cooling systems that minimize ∆T, super-insulated seasonal energy storage tanks, ground to air heat exchanger integrated with 97% efficient ERV/HRV including oversized fan coils and cool air flush, a hybrid electric thermal storage system using a water to water GSHP with a COP over 7.0, and programmable automated controls (PAC), it certainly appears that such a state-of-the-art high thermal mass structure could reduce energy consumption by well over 80% (according to modified options using current BEopt categories) in comparison with stick-frame construction.



Increasing thermal mass by constructing interior walls, floors, ceilings/roofs with ICF and concrete slabs could substantially increase energy conservation. This could reduce the size of the solar thermal collector system by over 50% without affecting the performance of the space heating or DHW systems.



For concrete mix designs which include pozzolans such as fly ash and silica fumes, etc., this enhances the heat capacity of the concrete and slows the release of thermal energy. Hence, the ability to model and simulate conservation of energy via high thermal mass of concrete should include a category focused on concrete mix design including percentage and types of pozzolans used, amount of air entrainment, etc. For example, CeraTech's heat resistant concrete (which dramatically increases fire resistance for meeting or exceeding building codes) has twice the heat capacity and conducts heat five times faster than ordinary portland cement:



http://www.ceratechinc.com/Products/FIREROK/ThermalResistance



As portrayed in the attached illustration, passive thermal storage is incorporated into buildings to smooth out temperature swings, delay heat entry (such as concrete and solar thermal collectors that absorb solar heat and conduct it into a structure over the course of several hours), absorb energy surpluses such as solar heat or heat from computers or other appliances, or to store heat as part of a passive solar heating system.



Though the attached illustration is based on a specific product for a particular ICF manufacturer, similar though varied results would be obtained from different products with lower or higher thermal mass (volume of concrete used in walls, floors/ceiling and roof structures, etc., as a component of a thermal battery storage system).



For an all ICF/concrete structure the volume of thermal mass and ability to stabilize thermal temperature within that structure would be dramatically enhanced via an integrated solar thermal and water to water 100% variable GSHP HVAC system.



ICF exterior walls and connected floors and vaulted ceiling have a high storage capacity with moderate thermal conductivity. Thus, it provides the most useful level of thermal mass sandwiched between EPS foam layers. This helps to stabilize the internal temperature resulting from day to night temperature fluctuations.



This is particularly true if a thermal battery, such as a super-insulated concrete cistern can be economically utilized to store solar thermal energy. Such an integrated system which may include a water to water 100% variable GSHP and desuperheater is used to bridge passive and active thermal storage technologies for development of an innovative hybrid thermal energy storage system.



Obviously, the above estimations could be validated through the addition of specific BEopt categories that would enable us to accurately model and simulate conservation of energy via high thermal mass structures, particularly in conjunction with hydronic-radiant floor heating and cooling systems, strategic design, and programmable automated controls for continuous concrete buildings with calculations based on total thermal mass of the structure.



Accurate modeling tools for high thermal mass structures integrated with hydronic-radiant heating and cooling systems would allow us to accurately determine energy savings and then size HVAC equipment including integrated solar PV and solar thermal collectors accordingly.

Rod Stucker

Type of Throw Rugs & Radiance from Continuous Concrete

I have been informed by mechanical engineers who design and instal radiant flooring that some throw rugs which are thin and lightweight have a minimal effect on the performance on radiant floor heating?? It sounds like that might be another matter for debate??



Regardless, as explained above and subject to demonstration, for all concrete floors/ceilings via ICF panels constructed in T beam molds, the radiant floor tubing inserted in the floor slab will conduct thermal energy through the entire floor/ceiling structure even in the presence of some interior EPS insulation as the bulk of the EPS insulation will be on the exterior of the structure. Hence, we should get some radiant effect from the ceiling and walls for both heating and cooling modes for continuous concrete structures. This is a difficult concept for many to comprehend since it has rarely been demonstrated. Very few ICF structures actually use continuous concrete construction.

Gordy

Thermal Mass

The control strategy could be tricky in that getting the btus when you need them, and where you need them, and keeping them at bay when you do not. the more high mass surfaces involved the higher the level of control needed.



I see seasonal transitions as hurdles for short periods of time. Fly wheel effect depends on how aggressive these seasonal changes happen.



I'm intrigued by this project, but Im wondering about actual real life marketing potential of such a dwelling once dialed into a production aspect. The more complex the more they run away. Lots of widgets to go bad, and replace over time.







Heck Mod/Con boilers were all the craze when they hit the front. Now we have certain people at all levels wondering about ROI for such a high maintenance complex piece of equipment as compared to a CI boiler.



Will the time come when they are the Norm yes, and its only when people dont have a choice in the matter is when these energy conservation products/structures become common place in society sadly it usually happens when its to late.



Just look at the missed opportunity from the last housing bubble. If some hard line standards for conservation were in place think of the potential that could have been.





Please dont take offense to my post Rod I see good potential with your project. But there is the devils advocate in me that sees how far the sucess will go in the market place.

Rich_49

Minimal Effects

in a building which is close to passivehaus and NZE standards is nonsense . MEs in my opinion have no business getting involved or opining on Physical things , if they were qualified to do so they would be PEs .We are not talking about a mechanical reaction but more of a physics thing .  I once had an engineer tell me and I can provide written proof of discussions , that because a radiantly heated overpour had such mass that a 230K boiler installed in a 100+K home would not short cycle . Now I agree that upon initial heating of the mass this is so but what about the other 150+ days of the heating season ,120 of them being shoulder season days ?  Why did he make the WM Ultra 230 , because it also would make the DHW , guys like this should ask for a refund from the institute of higher education which they attended . Mechanical engineers will hurt you proving your concept save for a select few who get it . 

I can agree with the ICF walls exterior but what you are going for as described by yourself will not benefit or prove concept my friend besides adding monstrous first cost . I am not saying to build a cheap building but more that spend the money wisely or the very guys you are trying to appeal to will chew you up and spit you out like a bad clam .

 The people in that community are deaf , dumb and blind and use such screwed up calculators figuring ROI instead of energy efficiency , thermal comfort , exergy , efficacy that I cannot believe they are regarded . As Joe L said , " It's about the energy Stupid "   I recently read a highlighted article about what a good job some builder in Mass did by installing 2 ductless mini splits totaling 23,000 BTUs in a 10,000 BTU home . Why was he so smart , because it was cheap .

  Whatever you end up with they will kill it unless the first cost , comfort , life cycle cost and everything is better . What it boils down to is when hydronics enters the picture it may very well expose the fact that ducting for anything other than ventilation and removing latent load creates problems in any building , without those problems the whole home performance industry that has evolved rapidly within the last couple of years will become null and void .

These guys have created a whole industry to combat the problems associated with and / or created by systems that are outside the thermal envelope directly being connected with the living space .

They will spend 1000s upon 1000s of dollars to make a house tighter than practical to the point where anything you install is oversized and they wholly discount true passive strategies because they try to use 2-3 solar thermal panels for DHW and still spend money on fuel . If they would adopt the idea that if you put 10 solar thermal panels or a panel like you speak of they could do all the DHW and space heating using a storage system and a couple watts of pumping power they would really be able to shout from the mountain top . But if they do that they will just showcase the fact that they have been doing it wrong for awhile now , that won't happen .  

  Here is a spirited discussion right up your alley , http://www.greenbuildingadvisor.com/blogs/dept/musings/all-about-radiant-floors

   

Rod Stucker

Where's the Horse??

No offense taken Gordy. I understand a little about the challenges of technology transfer and the need for early adopters. You will appreciate the following story:



At the turn of the twentieth century, thermodynamics were all the rage in the scientific and engineering communities. One day an engineer was explaining how the steam engine worked to a peasant farmer (who is reminiscent of contractors). The engineer said you put wood in the boiler and that creates steam. The steam pushes the pistons which turns the crankshaft and the wheels. The peasant farmer thought about what the engineer said for quite some time. He finally responded, "Yea Yea, I understand all of that, but where's the horse." In conjunction with this discussion, the question is "Where's the house."



Often times we get so used to doing things a certain way, that change is difficult to accept, and seemingly impossible to embrace for most people. However, it is those who recognize and appreciate innovation and emerging technologies who will reap the benefits of being pioneers and early adopters of progrogressive technologies.



The incentive for homeowners will be the economic savings (virtually no utility bills for ZNE homes), the increase in quality including home automation, and the durability of the concrete home that can better withstand natural disasters such as fires, floods, mudslides, earthquakes, and hurricanes, etc.



The real question is, can we do it for about the same cost as building a stick-frame home? After a year of research I am optimistic, but it will require a paradigm shift in the way we think about and implement energy efficient technologies. It will also require direct purchasing of materials and equipment as much as possible, and innovative construction management. In short, it requires a systems approach to design, purchasing materials and equipment, and construction of zero net energy homes. Of course, some sweat equity will be required on the part of the homeowner if they want to bridge the gap between passive house design and zero net energy smart homes including home energy management and automation.



Though the following attachment is still a work in progress, if you can make it through the executive summary you will hopefully begin to see the light at the end of the tunnel!

Rod Stucker

Just Tell us How You Really Feel!!

Rich, some might be offended by your candid remarks, but not me. The reason is, I share your concerns! However, I am an optimist by nature, and it appears obvious from reading your remarks, that from a technology perspective, we agree more than we disagree.



Those who are innovators are often scoffed at and called idiots until they succeed. Then, perspectives change and people learn that the world isn't flat after all. What was once considered to be preposterous emerges as a major breakthrough in technology, when in reality it is merely leveraging modern technology via more efficient methodologies.

Rod Stucker

Automated Windows vs. ERV Cool Air Flush

I agree that automated windows programed to open when the outside air temp. drops below targeted inside temp. is a desirable feature, but as you say spendy. In addition, fixed or picture windows are considerably more energy efficient than operable windows. For that reason, except for satisfying ingress/egress requirements, all of the ZNE-PHMH windows will be picture windows.



Wouldn't a cool air flush incorporated into the ERV/HRV accomplish the same purpose but with lower costs, e.g., providing an economic alternative to fully automated windows? I realize you wouldn't have as much airflow, but then again, over a period of 5-6 hours it would appear that the cool air flush provided by the ERV/HRV would be more than sufficient??



I can see where a small DC/ECM motor on an automated shade would be advantageous to limit solar radiation, assist with preventing overshooting, and enhance thermal resistance at night when the sun goes down. However, I am thinking that fully automated windows would be cost prohibitive and impractical for most residential applications?

SWEI

Fresh air

has become a major focus in the past decade or so and is not to going away any time soon.  The ROI for HRVs and ERVs is quite dependent on climate from what I have seen, and for most of the Intermountain West they are a tough sell.  Continuously exhausting 100 or so CFM from a house (about what we need for most radiant jobs) is just not a big enough hit to justify the added cost and complexity of an ERV once you add ductwork, filters, and controls.



Motorized windows seem to end up in expensive houses and hard-to-access commercial or retail spaces around here.

Rich_49

New Standard

Swei check out the new ASHRAE 62.2 standard . It will blow your mind , these guys now want 1 - 1.5 ACH . Kinda makes you wonder why we bother .  So the average 2,000 foot house needs north of 266 CFM fresh air . I'm telling you , whenever we figure out how to make it truly comfortable and efficient they come up with some energy wasting scheme .

Rod Stucker

ERV/HRV CFM

If I remember correctly, Ultimate Air's Recouperator provides 200 CFM maximum. So, in order to be compliant with the new ASHRAE standard while providing cooling/heating coils for regulating humidity and supplementing radiant floor heating and cooling, for a 2600 sqft footprint you would need to install one on each floor (including the basement and attic space that are converted into value added living space via continuous concrete structures), or go with one of their commercial models that is capable of substantially increasing the CFM. The Zehnder Comfoair 550 provides 325 CFM. I am sure there are also others that can provide similar or perhaps greater CFM. It does seem like it would become cost prohibitive for all the parts and labor for conventional ducting, etc. It might be easier to install if SDHV and ECM technology was used, the aspiration for which I am told compliments radiant heating and cooling.



I did locate the following ERV designed to meet the new ASHRAE Standard 62, Ventilation for Acceptable Indoor Air Quality:



http://lorencook.com/PDFs/Catalogs/ERV_Catalog.pdf



How efficient would this ERV be? Models begin with direct drives of 500 and 1,000 CFM, and extend up to 10,000 CFM using alternative belt drives which indicates that it is primarily designed for commercial applications, but could also be used for large residential applications. From a brief review, there is software available for designing the ERV and ducting system. Remote speed control and an automatic pressure controller are available on their EC motor products. The velocity range is such that it could be used for high pressure/velocity applications such as SDHV. They will install heating and cooling coils as requested.



In would imagine that Ultimate Air and Zehnder along with others will eventually come out with higher CFM models to comply with ASHRAE 62.2-2013-2.

Rod Stucker

Air-tight Concrete Structures

For continuous concrete structures that can achieve close to 0 ACH, I can see where ventilation may exceed 300 CFM/2000 sqft. Using SDHV technology, the 5.25" circular utility channels could be used to insert 2-3 inch circular ducts. There are two utility ducts for each 2 ft. of Quad-Deck/InsulDeck's ICF panels.



Refer to the attached illustration for the ICF panel vaulted roof assembly. The same ICF panel minus the roof insulation will be used for construction of each concrete floor except for the basement slab.

SWEI

ASHRAE 62.2

I have been following along for awhile now, and I have to say I disagree with their latest numbers (at least with regards to the houses we are building here.)  I suspect the uproar over 62.2-2013 will drive another revision, or at least some alternative methods.

Rich_49

Joe L

already has published a competing and competent standard . I believe it is posted at Building Science Corporations' site .

Rod Stucker

ASHRAE 62.2-2013-2 Standard for Ventilation

If I am reading correctly, the current ASHRAE Standard 62.2-2013-2 formula is comprised of the following criteria:



7.5 CFM x (Bedrooms plus 1) + (0.03 x sqft)



Thus, for the PHMH-2600 with a full basement and 6 people living in the structure, the calculation would be as follows:



7.5 x 8 + (0.03 x 5200) = 216 CFM for 5600 sqft



This is equivalant to 38.57 CFM/1000 sqft which is substantially less than the 133 CFM/1,000 sqft that Rich has referred to via 266 CFM/2000 sqft??



I located the following today (important issues for which I have italicized)



http://www.achrnews.com/articles/127235-ashrae-standard-622-gets-a-makeover



ASHRAE Standard 62.2 Gets a Makeover

Significant Changes Will Affect Residential HVACR Contractors

By Joanna R. Turpin

August 4, 2014



It has been more than 10 years since ASHRAE introduced Standard 62.2, “Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings,” which was developed in response to concerns about increasing levels of indoor contaminants and mold growth in residential buildings. The standard, which may be applied to new or existing homes, defines the minimum requirements for mechanical and natural ventilation systems and the building envelope so as to provide acceptable IAQ in low-rise residential buildings.



As a continuous maintenance standard, a new version is published every three years, with the latest version being released in March 2013. Some in the HVAC industry may be surprised to see that this version contains some significant changes, including a major difference in the way outside air is calculated. While contractors may not yet feel the effects of these changes, they will in the future, which is why they should familiarize themselves with the new version of Standard 62.2.



Changes in Store

The committee tasked with revising the standard, ASHRAE Standing Standard Project Committee (SSPC) 62.2, consists of approximately 20 people whose backgrounds range from research to engineering to manufacturing. The chairman of the committee, Paul Francisco, a research engineer and coordinator of the Indoor Climate Research & Training program at the Illinois Sustainable Technology Center at the University of Illinois at Urbana-Champaign, noted there were a number of major changes made to the 2013 version of the standard, but two are particularly significant.



The first change impacts how natural infiltration is calculated and accounted for. In the 2010 version of the standard, every house was assumed to have at least 2 cfm of natural infiltration per 100 square feet of floor area, Francisco explained. If an airtightness measurement was performed, it was possible to get half credit for estimated infiltration above that default level.



The new version takes into account more weather data, including the impact of wind, which resulted in lower calculated infiltration rates. “However, because the wind assumptions were more conservative, the committee felt comfortable giving full credit for infiltration above the default level rather than the half credit that had been provided previously,” he said.



The second change involves the removal of the default infiltration of 2 cfm per 100 square feet, which has been in the standard since its inception. “Newer homes are often much tighter, and the committee felt that assuming every home had that much infiltration, at a minimum, was no longer valid,” said Francisco. “Therefore, the decision was made to remove the default credit and require that any credit for infiltration be based on measured home airtightness.”



Paul H. Raymer, chief investigator, Heyoka Solutions LLC, Falmouth, Massachusetts, and a member of the SSPC 62.2 committee, added that by applying the infiltration credit calculation, the whole-building ventilation rate (which is calculated using the area of the building and the number of people in the house, represented by the number of bedrooms) can be adjusted to match the actual performance of a specific house in a specific location. “Ventilation for the number of occupants did not change in this version, but the ventilation based on the area of the building did change from 1 cfm per 100 square feet to 3 cfm per 100 square feet.” So, in the new version, mechanical ventilation rates are increased to 7.5 cfm per person plus 3 cfm per 100 square feet.



Another significant change made to the standard is the requirement that a carbon monoxide (CO) alarm be installed in every home — not just those with combustion appliances or attached garages. The rationale for this, explained Francisco, is that the most rapidly increasing cause of CO poisoning is the indoor use of combustion equipment that was not meant for indoor use, such as generators, power tools, and heaters.



The new version of the standard also includes the removal of climate-based restrictions, so, essentially, supply fans can now be used in cold climates, and exhaust whole-building ventilation can be used in hot humid climates. As Francisco noted, it was discovered that problems such as mold in humid climates and dryness in cold climates were caused by other factors (e.g., vinyl wallpaper, leaky buildings) rather than the type of ventilation system installed.



Lastly, a new section on multifamily buildings was added, clarifying that the ventilation rate for each individual dwelling unit must be calculated as if that unit was a single-family home, except there is no allowance for an infiltration credit since unit air leakage could be due to adjacent units, said Francisco.



Practical Application

The new version of Standard 62.2 hasn’t yet affected Sonoran Air in Phoenix, which specializes in the installation of HVAC systems in new construction and custom homes in the Southwest, said Greg Cobb, president and CEO. “The majority of our installs are part of the Energy Star program, which still follows the 2010 version of Standard 62.2. Non-Energy-Star installs fall to code levels of ventilation, which are similar to the 2010 version of 62.2 as well.”



Cobb has some issues with the new version of 62.2, noting the standard has become increasingly complex, but still does not address key issues. “Fresh-air ventilation rates are a semi-educated guess at best because homeowner lifestyles and occupant densities vary significantly. Opinions on the proper levels of fresh air vary widely as well. While I understand the reasoning for the change — because homes today no longer have the same infiltration levels that were assumed acceptable a few years ago — it is extra complexity that is not helpful.”



As a result of this complexity, Cobb believes many installers will not take the time to measure and calculate the infiltration offset specified in the new version of the standard. He assumes they will just use the basic formula, which will lead to over-ventilation. “Over-ventilation will lead to more noise and higher utility bills, which will cause many homeowners to simply disable their ventilation systems out of frustration, leading to poor IAQ.”



Francisco noted he has received similar feedback from contractors who are concerned the procedure for calculating infiltration is more complicated; however, he does not believe this to be the case. “In previous versions, the calculation procedures were not included in the standard, but rather referred to in other documents. Now, instead of having to go to three other documents, all of the calculations are in 62.2. It looks messier, but there are tools available that cut through the complicated math.”



The biggest concern Francisco has heard from contractors involves the removal of the default infiltration credit. “A lot of people are concerned the change is causing required ventilation rates to skyrocket. I agree, this is the case if an estimate of infiltration is not made, but if people do blower door tests, the impact is not going to be that big for many homes. However, I understand people don’t want to do blower door tests, and they also don’t want to put in more mechanical ventilation. This change means people don’t get both.”



Raymer also acknowledges there have been concerns about the change in airflow rates in the new version of the standard, but he maintains the issue is more fundamental. “Until recently, mechanical ventilation issues have been generally ignored, but it’s pretty simple, acknowledged Raymer. “Homes are being made tighter to save energy and reduce the impact on the environment; people still need air to breathe; tighter homes trap pollutants, which need to be removed or diluted; and mechanical ventilation is an element of that removal and dilution process.



“Contractors need to recognize that mechanical ventilation is a critical component to keeping people healthy in tight homes. Once they accept the fact that mechanical ventilation is necessary, they will find the new version of the standard to be a great resource generated by a group of very dedicated people who are experts in residential ventilation.”



Still, there is no question that transitioning to the 2013 version of Standard 62.2 will require a change in business practices, said Cobb. “In the markets we serve, most homes are tested by energy inspectors after HVAC startup and commissioning of the ventilation system. Thus, the blower door test to measure infiltration is not known at the time the ventilation controller is programmed. With the new version of 62.2, either the HVAC contractor will be responsible for measuring infiltration rates at startup, or else the energy inspector will be responsible for programming the ventilation controller.”



Cobb believes there are better ways to achieve reasonable IAQ rather than having the standard mandate that outside air be introduced at a set rate, whether or not it is needed. He would rather see the committee set IAQ targets and allow for intelligent controls and sensors to determine when and how much outdoor air is needed. “This would simplify the task for contractors and encourage homeowners to actually use ventilation systems that are installed and not just view them as wasting energy and money.”



SIDEBAR: More Changes Coming

ASHRAE recently proposed another change to Standard 62.2: Dwelling units of multifamily buildings of any height would fall under Standard 62.2, rather than Standard 62.1-2013, “Ventilation for Acceptable Indoor Air Quality,” which currently has responsibility for multifamily residential buildings that are four-stories tall or taller.



According to Paul Francisco, chair of the Standard 62.2 committee: “This will provide consistency of ventilation requirements for dwelling units regardless of building height. For new construction, this will result in a change of requirements for dwelling units in four-plus-story buildings. For the retrofit market, this change will result in coverage by ASHRAE ventilation standards for the first time in four-plus-story buildings.”



Other changes to Standard 62.2 are currently underway, as well, including one that has already been approved but has not yet been published. “This would bring unvented combustion into the scope of the standard, and users should expect to see something about that in the 2016 edition,” said Francisco.



There is also an interest in focusing on specific contaminants because particles — particularly in kitchens — have been identified as a major health risk, said Francisco. “We also would like to provide more explicit guidance in the standard on options that may reduce costs without impacting health. For example, maybe lowering ventilation rates when outdoor temperatures are more extreme, and natural infiltration is higher, with rates being increased when it is mild outside to compensate. This would better account for infiltration rates and increase ventilation when conditioning costs are low.”



Francisco expects other issues will be considered as well, such as differences due to ventilation system type, filtration, etc. “We also would like to simplify the flow of the standard to make it more user-friendly. When changes are made on a consistent basis, it is bound to get messy, and it can be helpful to reorganize the flow, even if no changes to substance are made. This also would have the potential to address some of the concerns that are raised by users.”

Rod Stucker

Sensors & Intelligent Controls

In summary of the above, if current sensors and intelligent controls are capable of accurately measuring and maintaining air quality, then I agree with the following:



"There are better ways to achieve reasonable IAQ rather than having the standard mandate that outside air be introduced at a set rate, whether or not it is needed. We should encourage the ASHRAE Standard 62 committee set IAQ targets and allow for intelligent controls and sensors to determine when and how much outdoor air is needed. 'This would simplify the task for contractors and encourage homeowners to actually use ventilation systems that are installed and not just view them as wasting energy and money.'”



However, we still need a starting point, e.g., a way of calculating the maximum and minimum ventilation for the desired structure, and provide additional CFM for cooling and heating via ERV or air handler coils that are fed by the ERV, and humidity regulation, etc. Hence, the current ASHRAE Standard 62.2-2013-2 appears like a good place to start when designing a ventilation system for maintaining an acceptable level of air quality.



If when cooling/heating coils are added to an ERV, and CFM is increased to accommodate those requirements and for also for simultaneously regulating humidity via the latent element of the cooling process to avoid dropping below the dew point temperature in the heating mode, then the ASHRAE Standard 62.2-2013-2 is usually exceeded anyway. This is particularly true for very tight envelopes such as that which passive house design provides (which includes continuous concrete structures).

Rich_49

ASHRAE 55

is the standard we all should be trying to achieve . If it can be achieved efficiency will follow , 62.2 must also be addressed . Sorry about the prior mention of discussions prior to the adoption of 62.2 2013. BSC's standard replaces .03 with .01 and this is more than adequate ventilation for any home .

 It would add an additional .16 ACH to your discussed home where as 62.2 would add .16 ACH . let's face it if you build a house to a .35 and add another .31 what are we doing ? A point 66 ACH house is not what we are shooting for . That point 02 extra in 2 million starts adds up to quite a bit of burned fuel guys .  We already take great steps to get rid of the bad stuff .

SWEI

BSC alternative proposal

Do you happen to have a link to this?



Can't seem to find it with http://www.buildingscience.com/@@search?SearchableText=62.2+2013 and there is a nice discussion here http://www.buildingscience.com/conversations/ventilation-rates but they BSC has a LOT of info.



thanks~

Canucker

Here you go

http://www.buildingscience.com/documents/special/ventilation-new-low-rise-residential-buildings?topic=specialprojects



It was hiding in the special projects section

SWEI

Thanks

One of the few places I didn't look.