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effects of Floor Insulation on indoor temperature

asked 2018-05-31 06:17:23 -0500

Constance's avatar

updated 2018-05-31 08:06:54 -0500

I created a simple house (only one zone with a roof on top) for Melbourne, Australia Climate: the roof is metal decking, ceiling is insulation of R5.0 m2.K/W, external wall is brick veneer with insulation of R1.5 m2.K/W, floor is 0.1m concrete floor on slab.

I changed floor insulation and external wall insulation separately and both results are quite strange:

  1. when I add insulation of R0.3 m2.K/W to floor, the indoor operative temperatures will change a lot (max difference: +7°C/-3.1°C).

  2. If I change the wall insulation from R1.5 m2.K/W to R10 m2.K/W, the indoor operative temperatures will only change a little (max difference: +0.6°C/-0.58°C) and values of the External Wall Average Face Conduction Heat Transfer Energy will be quite similar.

The results seems not corret as insulation of R0.3 m2.K/W to floor shouldn't has such large effects on the indoor temperatures and the average face conduction heat transfer energy of external wall shouldn't be similar for insulation R1.5 and R10 m2.K/W.

Please see the link I have put my modelling and comparison of the indoor temperatures in the dropbox:

Does anyone know why the effects of the insulation of floor on indoor temperatures is so huge and the insulation of external wall has such small effects on the conduction heat transfer energy?

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@Constance what kind of ground temperature model are you using?

Avi's avatar Avi  ( 2018-05-31 22:15:41 -0500 )edit

I didn't set up ground temperature. The default value 18.0°C are used throughout the year. The zone is unconditioned (no HVAC and didn't turn on the ideal air loads).

Constance's avatar Constance  ( 2018-06-01 00:12:15 -0500 )edit

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answered 2018-06-01 04:17:41 -0500

Avi's avatar

As I answered in your other question before if you are not setting ground model for small, ground attached buildings you are prone to have anomalies. I had the same until I incorporated the Kiva foundation.

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I have tried to use slab program and Kiva foundation. The results are still quite strange. When I increased the wall insulation to R10 m2.K/W (original is R1.5m2.K/W), the indoor temperatures will only have a small change (+0.4/-1.4°C). When added insulation R0.3m2.K/W to the concrete floor, the indoor temperature will change a lot (+4/-2°C).

Constance's avatar Constance  ( 2018-06-04 01:54:18 -0500 )edit

BTW, when I use Kiva Foundation, the average conduction heat transfer of floor surface disappeared. Do you know how to get the data related to the conduction heat transfer of floor surface when I use the Kiva Foundation?

Constance's avatar Constance  ( 2018-06-04 04:20:38 -0500 )edit

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Asked: 2018-05-31 06:17:23 -0500

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Last updated: Jun 01 '18