Serenbe Modern Proud Green Home Update: Heating, Ventilation and Air Conditioning Systems

Proud Green Home at Serenbe, LG Squared, Inc., Architect

Things are really moving along on the Proud Green Home at Serenbe. This past Friday, the mechanical inspector paid a visit and we passed! Ahead this week; the builder has ordered the final plumbing inspection, the sprayfoam contractor is installing the open-cell foam in all the walls and roof, we will be performing the pre-drywall inspection for EarthCraft House and ENERGY STAR certifications, and we will be hosting a construction tour of the home with the builder. If you’re in the Atlanta area this Wednesday, please stop by! We’d love to show you around.

For those of you who can’t make it, here are photos from the installation of the heating, ventilation and air conditioning systems that just passed the rough-in inspection last week. VIS VIVA Energy and Services, a local contractor who have successfully installed many of our HVAC designs, installed all of the systems. Vis Viva is also providing the additional air sealing services and installing the spray foam for the home.

As mentioned in a previous post, the home wlll be heated and cooled by the Ducted Mini-Split Heat Pump system (a.k.a. Variable Refrigerant Flow, VRF) by LG Electronics, and fresh air will be provided throughout the home by Zehnder America. Feel free to check out Zehnder America’s video on how their systems work, narrated by a guy with a great German accent!

Design Summary:

  • Design per ACCA Manual J, S, T and D, and ASHRAE 62.2
  • Home: 2,700 Square Feet, 4 Bedrooms, 3.5 Baths
  • Design Temperatures: Heating – 26°F, Cooling – 91.5°F
  • Heating Load (99%): 22,700 Btuh
  • Cooling Load (1%): 18,960 Btuh (Sensible), 2,400 Btuh (Latent)

Heating and Cooling Equipment Summary:

Ventilation Equipment Summary:

The Installation

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe

The HVAC Contractor, VIS VIVA Energy and Services, showing up for duty, SIR!

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe

Hauling in the concealed ducted fan coils, and Lance Beaton (Owner, VIS VIVA) in the background “making a plan” with his crew chief, Julio.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe

One of VIS VIVA’s crew bringing in a couple of the custom supply and return plenum transition pieces.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, air sealing, mastic

Our specifications call for a maximum tested duct leakage of 2% (or 2 cfm per 100 s.f. of conditioned floor area). A liberal use of mastic is a really good way of achieving that. Here is one of many connections showing the mastic at least “a nickel thick”. VIS VIVA has consistently been delivering 2%, or less, duct leaking on recent jobs. Well done!

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Here is a shot inside one of the supply register boots. Now THAT is what I call a “liberal” amount mastic!!

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, duct insulation

Julio and the fellas insulating one of the main supply take-offs, and doing a neat and tidy job of it. Very snug!

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, concealed ducted fan coil

Here is one of the three concealed ducted fan coils being used to serve three separate zones in the home. This one, a 9,000 Btuh capacity unit, will serve the entire second floor where we have 3 bedrooms, 2 bathrooms and a flex space.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, concealed ducted fan coilHere is the 12,000 Btuh fan coil serving the main living area, kitchen, dining and foyer. It’s being installed in a dropped ceiling area in a small alcove just outside the Laundry Room. Vertical clearance for these units is 12″. Transitions allow the plenums to deliver or return adequate air flow to and from the unit.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, concealed ducted fan coil

The upstairs unit in the encapsulated attic with the refrigerant lines ready to be attached. All ductwork was insulated to a minimum R-6.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, concealed ducted UnitThe third ducted unit in the Master Suite. It will be installed like the one serving the main living area between the floor joists and dropped ceiling framing in the His Closet of the Master Bedroom.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, manual d duct designDuctwork installed withing the floor structure using ACCA Manual D Duct Design methods. The 2′-0″ extension helps build up static pressure in the duct system for better air flow and delivery.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, acca manual d duct designWhen we designed the house, it structural system, and the HVAC system, we lowered beams where we needed to allow the routing of ductwork. We used this as an opportunity to break up the open interior spaces (visually) of the main living, kitchen and dining areas. Normally the beam would be flush with the top of the floor joists, but planning ahead allowed all of it to work together. Win, win, win!

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, zehnder america erv comfoair 350 luxeThe main exchanger (or dampener) of the ComfoAir 350 ventilation system getting ready for set up and install. That’s Lance Beaton (Owner, VIS VIVA) laughing at me for trying to pick it up and put it in the attic without any help…show off!!

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, comfoair 350 luxe ervIn this exchanger, the “magic” happens. Fresh air comes in, it flows by air being exhaused from the house, and the fresh air stream recovers up to 90% of the heat energy from the outgoing air to pre-condition it before it enters the home. The four ports are for 1. Fresh Air intake, 2. Stale Air Intake, 3. Fresh Air Supply, and 4. Stale Air Exhaust. See the link for the video above for more on how the system works.

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Main distribution boxes ready for assembly. One for fresh air and the other for stale air.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, comfoair 350 ervInstalled on an exterior wall in the attic, the exchanger and distribution boxes are placed to allow for short runs of the main supply and exhaust ductwork. The exhaust and fresh air intake on the exterior wall will be placed a minimum of 10′-0″ apart.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, comfoair 350 ERVThe distribution ductwork is a flexible piping with a smooth inside and ridged outside. Each of these ducts will deliver supply air or return stale air to and from the distribution boxes.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, comfoair 350 ERV

Supply and/or return boxes that are installed in each room. Once the drywall is installed the cylinders are trimmed flush and the “designer” diffuser is installed.

moder proud green home, lg squared inc, architecture, architect, hvac design, installation, construction, serenbe, comfoair 350 ERVHere is another type of return box. This one has been installed in the powder bath on the side wall instead of the ceiling. A different “designer” diffuser will be installed after drywall.

That’s a wrap, folks!

Until next time, thanks for tuning in and watching one of our “babies” grow up!

Please let us know what you think of the progress or the systems we chose. If you can make it to our event, we look forward to meeting you. Please come say, “hello”!

Written by Chris Laumer-Giddens

 

 

 

 

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6 Responses so far.

  1. Jake Vierzen says:

    That’s pretty neat Chris, first time I have seen a ducted mini-split.
    What do the 99% and 1% mean? No, not what do they mean on talk radio, or to the current administration; you have that written after the heating and cooling loads in the design summary.

  2. Tom says:

    The 99% means the unit is big enough for the design load 99% of the time. They could have designed to a 99.8% standard, but would have needed @ 20% more capacity at that point.

  3. David says:

    Does a ERV system like the ComfoAir 350 eliminate the need for manually activated exhaust fans in bathrooms? What about long hot showers? What about a ventilation hood in the kitchen? If not, how to manual exhaust fans affect the performance of an ERV?

  4. David, it’s pretty common to use the ERV to exhaust areas like bathrooms, kitchens and laundry rooms. There have been cases where long showers can cause increased indoor humidity issues. The ComforAir has the ability to monitor the relative humidity and control how much of the moisture is being released back in to the home (through transfer at the core). Every house, and every homeowner is different, which is why everything to do with fresh air, heating, cooling, etc. has to be carefully analyzed for each case.

    The main reasons for this strategy is to 1. exhaust these areas with one central fan (each room has a call switch), 2. maximize energy recovery by pulling from multiple locations.

    I don’t always recommend this strategy, and I don’t specify connecting it to the heating and cooling duct system.

    Most ERVs don’t have the capacity to handle it, so connecting the kitchen ventilation is never recommended. There are other reasons, but that is the simplest.

    Separate exhaust fans should not have any effect on the ERV if installed per manufacturers recommendations and best practices. They should never be connected in any way, and you should only NEED one or the other in a given space. It’s possible to have both, but that just depends on the situation.

  5. Jake: The design temperatures for any given location are based on an average of temperatures gathered and published by ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers). 1% or 99% design temperature is a temperature that ASHRAE updates every 3 years that represents the temperature that a location (city, airport, etc.) will experience 1% of the year. They use averages over the past 30 years to come up with the temperature. Some jurisdictions will require higher or lower temperatures, but if they don’t, ASHRAE is what most programs and codes will require.

  6. [...] are a few shots of this system at the Proud Green Home. We have a more extensive post on the entire mechanical system at this home, including the Zehnder [...]