Passive house, or thick walls - it's not all

26.04.2011 07:15
Articles about real estate | Passive house, or thick walls - it Now now a lot of talk about reducing energy consumption of housing and one of the directions of this reduction - is warming the house. Let's get together Let us examine how much to insulate their own homes, and perhaps entirely abandon the consumption of energy in the form of electricity, gas, heat, supplying us with utilities and other commercial structures.
Understand this issue, I propose the following:

1. Will calculate heat loss through an ordinary brick wall (2 bricks thick - 0.5 m) insulated from the outside min wool and a wall with termodoma (wall structure, we take a = 32 & t = 109;

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2. Compare the cost of conventional walls and walls termodoma and calculate how much time Wall termodoma pay off;

3. To determine the main sources of heat loss and the possibility to eliminate them;

So start the calculation of heat loss through the wall will be spend in the program KANOZC and represent them graphically. The first calculation is made "regular" brick walls in 2 bricks thick (500 mm) and insulated from the outside min wool 100 mm thick.
Fig. A heat transfer coefficient 0.394 m2K/Vt.
Picture: Passive house, or thick walls - it's not all

Next, perform the calculation of wall termodoma's description of have the wall outside the insulated with 2 layers of foam glass with a total thickness of 240 mm. On the internal structure of the wall did not, so we take the same 2 bricks (500 mm).
Fig. 2 Heat transfer coefficient 0.241 m2K/Vt.
Picture: Passive house, or thick walls - it's not all
As you can see, there is a difference. Wall termodoma transmits heat out less, but let's look at how much less. The calculation, by comparison, spend the next - to calculate how much less need gas for heating 1m2 wall termodoma compared to "normal" wall.
The amount of heat passes a wall termodoma m2 - 0.241 * 42 = 10.12 W;
The amount of heat passes a m2 a "normal" wall - .394 * 42 = 16.54 W;
Given that 1 m3 of natural gas has a calorific value of property is 9.45 kW then we have:
Monthly gas consumption for heating the walls termodoma - (10.12 * 24 * 30) / (9.45 * 1000) = 0.77 m3/mis;
Monthly consumption of natural gas for heating the "usual" wall - (16.12 * 24 * 30) / (9.45 * 1000) = 1.26 m3/mis;
For a more illustrative comparison we take a house of 150 m2, oddly pilgrimage exterior walls of the house, too, 150 m2, at an altitude ceiling of 3 m. Therefore for heating 150 m2 of exterior walls termodoma to 0.77 * 150 = 115.5 m3 of gas, once tell you not to be confused with heating the whole house except the walls there are windows, doors, ceilings and ventilation, floor, for the usual wall of 1.26 * 150 = 189 m3 of gas. The difference 189-115,5 = 73 m3 per month (currently at 73 USD per month).
Now let's calculate how much more expensive version of the Wall termodoma from the "usual" wall. We compare only the outer insulation as an internal konyat design takes the same. The cost of foamed glass is from 2800 to 4000 grn/m3, the cost of cellular glass insulation 1m2 wall thickness of 240 mm without finishing will make, on average, 800 grn/m2. Cost of 1 m2 Min wool 100 mm thick is an average of 35 grn/m2. As you can see a significant difference, namely the 765 grn. These funds, if again we take a house 150 m2, enough to heat it for 50 years, provided the cost of gas 1 grn/m3. But if gas will raise the price then and insulated materials also will raise the price.
The conclusion - that too is not healthy. The costs of home insulation have an exponential dependence on the resulting effect, ie to reduce the wall heat at 0.01 m2K/Vt is 2 times larger than the previous costs, reduce the thermal conductivity of 0.1 m2K/Vt.
Since 2006 he has a new DBN B.2.6-31: 2006, in which the approval of minimum acceptable thermal conductivity of the exterior walls and other building envelope. For example, for our climate zone (Kyiv) for the outer walls have a 2.8 m2 * K / W, which in my view rightly so in terms of fuel savings and investment.

We now proceed to identify the main sources of heat homes and their share in total heat loss at home.
The main sources of heat loss in the home is:
1. Exterior walls;
2. Exterior windows;
3. Exterior doors;
4. Ventilation (though it is impossible to eliminate entirely - suffocate);
5. Roofing;
6. Sex;
Exterior walls have the highest or equivalent with a roof area, but as the roof and exterior walls are insulated with most of the house. Windows - are inherently the least secure parts of the building from heat loss (windows must be transparent. The heat loss through the floor are the lowest since the heat is given to the land, having a temperature higher than the outdoor temperature. For heating air flowing through the ventilation, power consumption as much as we are losing through the exterior walls. For comparison - propose to calculate the percentages in the area of ??the building envelope of a source and to compare their regulatory heat loss from the DBN B.2.6-31: 2006. On the ventilation talk separately.
So, take back a house of 150 m2 floor, with a gable roof, and windows 1.4 x1, 4h was accepted that the house has 4 bedrooms, bathroom, kitchen and hallway. Number of windows 11 pcs. total area of ??which amounted to 1,4 x1, 4h11 = 21.56 m2. Entrance doors 2 area 2.4 m2 each (total 4.8 m2). Consequently, the total area of ??all building envelope of 150 m2 (floor) + 123 m 2 (wall) + 180 m2 (roof) + 21.56 m2 (windows) + 4.8 m 2 (door). Total - 479.36 m2. Now, as a percentage:
- Exterior walls 22,5%;
- Paul 33%;
- Roof 39%;
- Windows - 4,5%;
- Doors - 1,0%;
Compare the offer as follows -% of the total area of ??each enclosing structure divided into regulatory resistance to heat, so we get an objective reflection of the distribution of heat. The less resistance the more heat design misses out at the same time its Living surface in the general area of ??the house may be minimal (I hope I get the idea):
- Exterior walls 22.5 / 2.8 = 8.0 ODN;
- Paul 33 / 3.75 = 8.8 ODN;
- Roofing 39 / 4.95 = 7.87 ADU;
- Windows 4.5 / 0.6 = 7.5 ODN;
- Doors 1.0 / 0.6 = 1.6 ODN;
Thus we see that all building envelope, in such a distributed area, have approximately the same share of the total loss of heat. But the heat loss through walls, floor or ceiling, we can adjust, but the windows need to be careful too trapping glass cherevate large heat losses. We can say that the main "spender" heat from the building there are windows, and with today's technology to reduce these costs, we can not. Therefore, when designing their homes to find a compromise between the light and warmth.
Ventilation - a single item of expenditure and heat, which is important in general to abandon it impossible. What share of heat consumption for ventilation, and take in the overall heat loss? From my own experience say that the ventilation heat loss takes 20 to 40% of the total heat loss through the building envelope. How to reduce these losses? Reduce possible, but one should always compare the investment with the obtained effect. To not get the same situation as with the wall. And one more for the use of various energy recovery, heat pumps and others. do not consider that they consume electricity and this electricity is also necessary to consider in determining the economic effect. By the end we all save their own money, but in some cases, the savings we only think.
Content tags: house Ecology Housing
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