[EnergyPlus_Support] Re: Insulating wooden floor raised 400mm from ground in temperate climates

["Ooi" <ooi_kb3@xxxxxxxxxxx>]

Hi Andrew, Jean and Dr Li,

i have created an idf with V7.2 EPlus, of the proposed 6.3m x 3.4m x 2.6mH Nanny House with the 400mm Crawlspace below. The walls of the Crawlspace is IR Transparent material. The IR transparent material is to allow solar radiation to reach the Crawlspace. 

Weather file runs with Melbourne Australia location shows that the Zone Mean Air temperature of the Crawlspace is more stable than inside the house with one occupant. 

It appears that insulation in the air gap between the brick and the veneer walls of the house would make the house warmer. i am trying to do away with the gas heater with underfloor ducts. 

Air Flow Network (AFN) would be required to model the vents between the living space and the crawlspace. Andrew, what coefficients are you using. 

ooi
   
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "drajperry" <drajperry@...> wrote:
>
> Thanks for your very helpful response.
> 
> I will model that way and then test different ground temperatures using the "SurfaceProperty:OtherSideCoefficients" object.
> 
> I have the approximate area for the vents from the building standard so can start with that and then do a parametric study to determine what value of venting to the outside is most consistent with the measurements. 
> As Dr. Li has pointed out previously you have to be careful doing that kind of comparison since the model is not based on actual weather conditions that applied at the time of measurement.
> 
> After that I will get on to insulation for the floor.
> 
> Thanks again to all on this thread,
> Andrew. 
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Jean Marais <jeannieboef@> wrote:
> >
> > earth can be a one material layer construction. materials can be freely
> > defined. create the air zone "floor" construction so that it references a
> > material "earth" which you define. DesignBuilder is currently applying such
> > a layer to the user defined slab construction as an additional material
> > layer and the underside of that layer is assigned the "ground temp" as
> > found in the weather file. Try it and see if it matches roughly your
> > temperature sampling. PS the venting to outside that you would apply to the
> > air zone will be crutial.
> > 
> > On 21 November 2012 11:43, drajperry <drajperry@> wrote:
> > 
> > > **
> > >
> > >
> > > thanks for the reply,
> > >
> > > My problem is that I am still unsure of how to define the material/surface
> > > for the bare ground/dirt that forms the lower boundary of the zone below
> > > the bare floor.
> > >
> > > The actual ground temperature there could also be slightly higher than the
> > > ground temperature defined in the weather file. Although it is vented I
> > > know from temperature logging that the air temperature is significantly
> > > higher than the outside air - the space above the bare floor is heated and
> > > the heating ducts pass through the sub-floor zone.
> > >
> > > For concrete slabs I just use the slab/basement model but that doesn't
> > > seem to handle exposed ground as the zone surface.
> > >
> > > thanks, Andrew.
> > >
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Jean Marais <jeannieboef@>
> > > wrote:
> > > >
> > > > In my opinion modelling a seperate cavity zone for air cavities will
> > > always
> > > > be more accurate and give you tighter control.
> > > >
> > > > On 20 November 2012 12:51, drajperry <drajperry@> wrote:
> > > >
> > > > > **
> > >
> > > > >
> > > > >
> > > > > Does anyone have a suggestion for the best way to model in EPlus the
> > > bare
> > > > > earth that forms the lower surface for the air space under the floor in
> > > > > this kind of construction?
> > > > >
> > > > > There is a lot of old residential housing stock here in Canberra that
> > > has
> > > > > this construction. Wooden floor (usually not insulated) raised above
> > > the
> > > > > ground with the space under the floor vented to the outdoor.
> > > > >
> > > > > thanks for the suggestions concerning insulation methods.
> > > > > regards, Andrew.
> > > > >
> > > > >
> > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@> wrote:
> > > > > >
> > > > > >
> > > > > > Sorry that my comment triggered so many responses. This is what
> > > usually
> > > > > happens, when only partial requirements were given in the post. We
> > > seldom
> > > > > walk bare footed at home. Dr. Ooi's house has been in use for a number
> > > of
> > > > > years. He is not going to simulate it with EPlus in detail. The
> > > vertical
> > > > > soil insulation I suggested was a standard application. We use it to
> > > > > minimum ground heating as well. This has been done using the EPlus slab
> > > > > program. In North America, hard wood floor is laid on top of plywood or
> > > > > concrete sub-floor. In my Singapore house , the woodien floor has
> > > dove-tail
> > > > > joints, but opened up due to shrinkage. They are laid on cross beams
> > > > > without a sub-floor. I assumed that Dr. Ooi's house has similar
> > > > > construction. The cold air from under the floor vented to outdoor can
> > > be
> > > > > quie cold in Winter. A rug would block the air as well. Yes, wood is
> > > warmer
> > > > > than ceramic, But the cold air on the bare feet is definitely not
> > > > > comfortable. I had no cold floor problem in Singapore, but we sill wear
> > > > > slippers in door and change to clogs when stepping outside. People
> > > like the
> > > > > cool concrete floor in Singapore. However, all the new high rise
> > > housing
> > > > > are all air conditioned for comfort. I still preferred my old house
> > > build
> > > > > with a 3ft air space below the whole building, 11 ft ceiling and with
> > > > > natural ventilation. . I am very sorry to see that practically no one
> > > in
> > > > > the forum is designing energy efficient residential units.
> > > > > >
> > > > > > Dr. Li
> > > > > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > > > > From: linda@
> > > > >
> > > > > > Date: Sat, 17 Nov 2012 13:16:09 -0700
> > > > > > Subject: Re: [EnergyPlus_Support] Insulating wooden floor raised
> > > 400mm
> > > > > from ground in temperate climates
> > > > > >
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> > > > > > At 01:12 PM 11/17/2012, Jean Marais wrote:
> > > > > >
> > > > > > I thought the use of the wooden
> > > > > > floor was exactly because it's not as cold as tiles.
> > > > > >
> > > > > > I think the wood has less thermal mass than ceramic, etc tiles. So,
> > > > > > tiles hold their temperature longer, so to speak. Or leach their
> > > > > > cold to your bare feet more than the wood (which more quickly
> > > responds to
> > > > > > the temperature of your feet).
> > > > > >
> > > > > >
> > > > > > Linda
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>




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