6 Comments

1. 
   ssnellings | Sep 14, 2020 05:51pm | #1

   The wall assembly sounds a bit unusual, is there additional information available about it? I checked their website and there is no information about this project that I could find (it's more of a real estate rental website).

1. GBA Editor
   Kiley Jacques | Sep 15, 2020 08:40am | #2

   Hi Sam,

   I have a pdf that illustrates the construction phases of the wall assembly. It's too large to share here but if you would like to see it, let me know by emailing me at [email protected].

1. 
   ssnellings | Sep 15, 2020 12:12pm | #4

   Thanks Kiley, just sent you an email!

2. Expert Member
   KOHTA UENO | Sep 15, 2020 09:03am | #3

   Sorry if this is beating a dead horse, but re this paragraph:

   Nonetheless, when that fell through, the developers turned to concrete as a solution, making a thermal mass argument in its defense. When pushed back against for that idea (Newburyport is a cold climate, where some would say thermal mass is not significantly effective), Hall cites this study by the Cold Climate Research Center, and suggests that when heavy walls and floors, such as those made from concrete, are combined with passive-solar-design strategies, there can be a reasonable reduction in heating loads. “Heating and cooling stability during a power outage is real in these buildings,” he says. “I believe this is a factor that will show up in the next generative of Passive House trainings.”

   I was curious what that CCRC report had to say... unfortunately, it is behind a paywall. But the abstract is available:

   The Effect of Thermal Mass on Annual Heat Load and Thermal Comfort in Cold Climate Construction
   https://www.researchgate.net/publication/273510198_The_Effect_of_Thermal_Mass_on_Annual_Heat_Load_and_Thermal_Comfort_in_Cold_Climate_Construction

   Thermal mass in building construction refers to a building material's ability to absorb and release heat based on changing environmental conditions. In building design, materials with high thermal mass used in climates with a diurnal temperature swing around the interior set-point temperature have been shown to reduce the annual heating demand. However, few studies exist regarding the effects of thermal mass in cold climates. The purpose of this research is to determine the effect of high thermal mass on the annual heat demand and thermal comfort in a typical Alaskan residence using energy modeling software. The model simulations show that increased thermal mass can decrease the risk of summer overheating in Alaskan residences. They also show that increased thermal mass does not significantly decrease the annual heat load in residences located in cold climates. These results indicate that while increased thermal mass does have advantages in all climates, such as a decrease in summer overheating, it is not an effective strategy for decreasing annual heat demand in typical residential buildings in Alaska.

   CCHRC also has a video on thermal mass--explaining what's pretty well known: it works great in climates with a high diurnal swing (high desert), and it can be a useful tool when doing passive solar design, acting as a storage component to the solar gain coming through the windows.

   CCHRC: Thermal mass in Alaska
   https://www.youtube.com/watch?v=eiCGAh1dVPI&ab_channel=ColdClimateHousing

   Re the power outage factor: I'd like to see what numbers people might come up with in simulations. My intuition is that the slab definitely stores heat... but given heat loss through windows, unless you have some operable insulation/shades, I'm guessing maybe a day or two (maybe?) of added comfort conditions, depending on exterior temperatures.

1. 
   user-6533823 | Sep 16, 2020 03:11pm | #5

   Hi Kohta, the decrease in heat load is not significant. The WUFI model put it in the 3% range. By itself not a reason to use the wall system. I will inquire what the model generates for indoor temp trajectory with winter power loss at various out door temps.

2. 
   dmaxwellmn | Jan 03, 2021 01:33pm | #6

   This makes total sense, a friend just messaged me last night about staying in an earth ship home in the south west and how amazed he was that the inside temp stayed comfortable all night even though over night temps fell to around 20F. I'm not sure what the daytime temp was but probably fairly warm and sunny, plenty of energy to heat up the mass of the building, especially using South facing glazing. Here in Minnesota, while we have had some sunny days recently there is no way that would work, of course. That said I have always been interested to live in a home with a mass wood heater, most importantly located in the center of the house, it always seemed like a really smart way to design a cold climate house, just put the mass inside and heat it with a fire. In the summer open the windows at night and use it as a heat sink during the day.