Hi A.C., Yes, I hear ya, but think: How would you have introduced this to someone who has already expressed the need/interest when you had that ability sitting in your lap? It certainly wasn’t a "blatant" plug. You are being introduced to a product not yet in the states; we will be looking for a master distributor next year and you will hear much more about it then. Think you have been given an inside hint about what’s coming in an area you obviously love.
There are great questions
, have a closer look at the site and our methodology will begin to make itself felt. It's not a "see all do all" solution for all locations, but for many places it is.
So for the sake of illustration, if you were building a home that was 2000 square feet in area, and the climate was such a severity that it required one Ton of conventional heating & cooling (1 Ton = 12,000 BTU/hr = 3.5 KW-h)...
• How much mass would you allow for the floor heat sink?
DSHH: We don’t tell everything on line or we cut our own throat, however: The design is a balanced system designed roughly for lowest cost in a give area with a give heat requirements. Sometimes this will only allow us to offset the heating load, which is why we added the Hot Water Heat pump and log wetback options.
We have an energy efficiency requirement to meet design parameters. It is engineered around certain fixed (Winter vs summer, temp expectations, thermal leak factor) & Variable parameters (Solar insolation factors, roof or adjacent real estate, water table level, earth type etc).
Based on the moderately high rate of loss given, this would be a moderate to cold climate in winter depending upon thermal efficiencies of the home. Missing from the equation is the heating window, for how long, or at what point do you no longer need to heat the home. These are just a few of the things we factor in.
In general we would ballpark this as 1.6CuM of Earthen thermal mass per SqM of warmed floor area. Thus for every SqM of floor space, we would design in roughly 1.5 SqM of thermal mass. This does not translate well into 1SqFt to 1 CuM.
To put this in perspective, for this guestimated design: One SqM = 1.5CuM of thermal mass. (3.29Sq Ft = 53Cu Ft) Thus we heat from the op an area about 1.6SqM deep for every SqM of Heated floor space. (5.25 deep per 1 Sq Ft)
• Does your design system account for the large range of ground temperatures you might encounter in Finland, Alaska, Southern Spain, Caracas, etc.?
Qualified Yes, however the law of diminishing returns forces us to assume a stance of offsetting the heat demand at a certain point, vs supplying all of it.
We are beginning tests in Canada next year in a location where winter temps get down to -45/-60c (-49f/-76f) in N Alberta. We have to figure out where to stop. In this area frost levels are 1.2M (4’) deep or more.
So far in NZ we have not had to add supplementary heat to any of our homes beyond solar and occasional use integrated log wetback use. We now have systems well into winter conditions of -15c (05f). As this is the only heat we have insisted they install a moderate How water heat pump which we also integrate into the hot water providing lower cost hot water on non solar days. We now are putting homes into one of the coldest towns in NZ, in the alpine region of the country.
• Would you use regular cement or does your system also feature change of state additives (Phase Change Material)?
No we use only require std 20MPa concrete and only in our ICF sub walls, we don’t specify the cement portion to the concrete at all.
We do have users who included insulation particles and air-entrainment, but with decent ICF thickness and the use of 90mm (3”) drain-flo EPS on the outside or inside of this thermal insulation levels are significant enough to contain most of the heat injected during the summer.
Remember, the bane of solar heating is not that it doesn’t work, but rather you need help over the dark days and bad weather. When you engineer the solar system to provide enough winter heat, you have huge summer overloads of energy, and rather than shut part of the system down in summer we inject the huge quantity of heat into a poor thermal mass which becomes saturated over time, doming down beyond 2.5M (8ft) below the insulation under the slab.
Visualize this as an 8 ft deep containment system the whole size of the house and you begin to get the feel of the huge area/qty of heat we are storing, usually just in time for winter if we have our calculation right, the thermal mass at the op sits in the 60-80c (140-175f) range after min 5 years of dumping vast amount of Kw of energy over every summer day and most of the should seasons, and much of the winter as well, as most of the solar array is quite large.
FYI I would guesstimate the solar array to be capable of min 13Kw, or over 280 Evacuated solar “U” tubes. These tubes still work well although at diminished capacity even down past 18c (0f)
• If it does use PCM, what is the formulation?
No, as it mentions on the website and above we use low cost in-situ earth, contained in ICF. It HAD to be low cost to work and be attractive, and not decrease carbon credits.
• Are you running PEX through the slab for heat storage and heat reclamation?
We run triple layered JH O2 proof pipe in both the slab and core, but at differing thicknesses and spacings.
• What kind of PEX spacing do you usually use?
We have to keep some things under our belt now don’t we ;-) Also we don’t normally use PEX
• Are you running straight water or do you use antifreeze?
Cold areas: System limited to 100c @ Min 35PSI use 50/50 Glycol
• How much insulation would you place under the floor to reduce loss?
Not much needed as it only serves to isolate the hot heat core from heating the slab in summer. Normally we use 90mm of HPDI special under floor high pressure steam popped EPS
• What percentage of heat do you estimate is nin-recoverable (lost) from your slab?
Very little is ‘lost’ from the slab, into the house excepted, if our specs are followed during construction. We loose about 50% from our heat containment in the early years improving by 50% more as years progress and the system reached stasis with the surround grounds outside the ICF containment area.
• How do you deal with interior summer heat while you are heating the thermal mass?
See above. It’s a balanced system. We will be getting an engineering firm or university to contract to ascertain many of the variables to be able to plug into a computer program. Right now we do it by and base educated guesstimates on experiences to date.
• Are you using radiant floor heating or have you placed an insulating layer over the heat sink structure and under the floor?
See above.
• Are you using inverter type mini-split heat pumps or are you going with inverter type central heat pumps and zoning the various areas of the house?
We don’t have access to inverter Hot Water heat pumps as yet. We would prefer them though. Right now we use 6-10kW HW units, a good deal as it heats the hot water as well at less cost than other fuels as a rule. We h\are installing one now in a very cold area where we put in 2 6kW units simply staged for cold weather. We estimate the 2nd one will only been needed occasionally when ambient insolation is obscured for long periods, even in winter.
• Does your scheme use continuously variable brushless fans for ventilation?
No supplemetary ventilation included we simply heat the slab fro warmth. It is not yet a full on package – later maybe. It use continuously variable brushless fans and low cost air-to-air heat exchangers.
• Are you employing HRV or ERV in the ventilating system?
No, customers choice. We don’t even recommend these with our full energy efficient designs as they typically blow cold air during winter nights. They do have their place.
• Are you using cross-flow, counter-flow or enthalpy wheel exchangers?
Nope, See Above.
• How many airc hanges per hour do you design to?
Non, we focus on the warmth aspect.
• Do your wall structures use a separate, inside utility-wall to prevent insulation wall intrusion?
Our current maximum spec for the EE home (not to be confused with the DSHH system) involves 200mm (8x2) with 95mm (2x4) offset studs, 12mm (1/2”) plywood sheathing with building wrap. In locations where external temps dip below freezing for more than 2 weeks at a time we add in a std vapour barrier. They glue gypsum boards here, and this drives them crazy.
To avoid this entirely we are now doing more homes & commercial completely out of ICF:1. Built in concrete thermal mass
2. Double insulation excellent R values, improved thermal efficiency
3. 90mm of Drainflo EPS almost doubles the thermal value
4. No risk of rotting timbers
5. No risk of wind ingress
6. Fantastic noise containment or rejection
7. All owners rave about their homes being warm and solid
8. Fast erection
time
Hope this helps, it won't work in every situation to eliminate alternate heating, we can calculate how much solar heat we can generate which will offset other forms of heating.
Cheers,
Ron @ DSHH.info