Of course, the main sources of heat loss in the house are doors and windows, but when viewing the picture through the screen of a thermal imager, it is easy to see that these are not the only sources of leakage. Heat is also lost through an illiterately mounted roof, a cold floor, and not insulated walls. Heat loss at home today is calculated using a special calculator. This allows you to choose the best option for heating and carry out additional work on the insulation of the building. Interestingly, for each type of building (from timber, logs, silicate or ceramic bricks), the level of heat loss will be different. Let's talk about it in more detail.
Basic calculation of heat loss
Control over heat losses is systematically carried out only for rooms heated in accordance with the season. Premises not intended for seasonal living do not fall under the category of buildings amenable to thermal analysis. The heat loss program at home in this case will not be of practical importance.
To conduct a complete analysis, calculate thermal insulation materials and select a heating system with the optimalpower, it is necessary to have knowledge of the real heat loss of the dwelling. Walls, roofs, windows, and floors are not the only sources of energy leakage from a home. Most of the heat leaves the room through improperly installed ventilation systems.
Factors affecting heat loss
The main factors affecting the level of heat loss are:
- High level of temperature difference between indoor microclimate and outdoor temperature.
- The nature of the thermal insulation properties of enclosing structures, which include walls, ceilings, windows, etc.
Heat loss measurements
Enclosing structures perform a barrier function for heat and do not allow it to freely go outside. This effect is explained by the thermal insulation properties of products. The value used to measure thermal insulation properties is called heat transfer resistance. Such an indicator is responsible for reflecting the temperature difference during the passage of the nth amount of heat through a section of protective structures with an area of 1 m2. So, let's figure out how to calculate the heat loss at home.
The main quantities needed to calculate the heat loss of a house include:
- q is a value indicating the amount of heat leaving the room outside through 1 m2 of the barrier structure. Measured in W/m2.
- ∆T is the difference between indoor and outdoor temperatures. Measured in degrees (oC).
- R –heat transfer resistance. Measured in °C/W/m² or °C m²/W.
- S - building or surface area (used as needed).
Formula for calculating heat loss
The home heat loss program is calculated using a special formula:
R=∆T/q
When calculating, remember that for structures consisting of several layers, the resistance of each layer is summed up. So, how to calculate the heat loss of a frame house lined with bricks from the outside? The resistance to heat loss will be equal to the sum of the resistance of brick and wood, taking into account the air gap between the layers.
Important! Please note that the resistance calculation is carried out for the coldest time of the year, when the temperature difference reaches its peak. Reference books and manuals always indicate exactly this reference value, which is used for further calculations.
Features of calculating the heat loss of a wooden house
Calculation of heat loss at home, the features of which must be taken into account when calculating, is carried out in several stages. The process requires special attention and concentration. You can calculate heat loss in a private house according to a simple scheme like this:
- Spot through walls.
- Calculate through window structures.
- Through doorways.
- Calculate through overlaps.
- Calculate the heat loss of a wooden house through the flooring.
- Add the values obtained earlier.
- Given thermal resistance and energy loss throughventilation: 10 to 360%.
For the results of points 1-5, the standard formula for calculating the heat loss of a house (from timber, brick, wood) is used.
Important! Thermal resistance for window structures is taken from SNIP II-3-79.
Building reference books often contain information in a simplified form, that is, the results of calculating the heat loss of a house from a bar are given for different types of walls and floors. For example, they calculate the resistance with a temperature difference for atypical rooms: corner and non-corner rooms, one- and multi-storey buildings.
Need to calculate heat loss
Arrangement of a comfortable home requires strict control of the process at each stage of the work. Therefore, the organization of the heating system, which is preceded by the choice of the heating method itself, cannot be overlooked. When working on the construction of a house, a lot of time will have to be devoted not only to project documentation, but also to calculating the heat loss of the house. If in the future you are going to work in the field of design, then engineering skills in calculating heat loss will definitely come in handy for you. So why not practice doing this work by experience and make a detailed calculation of heat loss for your own home.
Important! The choice of method and power of the heating system directly depends on the calculations you have made. If you calculate the heat loss indicator incorrectly, you risk freezing in cold weather or exhausting from heat due to excessive heating of the room. It is necessary not only to choose the right device, but alsodetermine the number of batteries or radiators that can heat one room.
Estimation of heat loss on the calculation example
If you do not need to study the calculation of heat loss at home in detail, we will focus on the estimated analysis and determination of heat loss. Sometimes errors occur in the calculation process, so it is better to add the minimum value to the estimated power of the heating system. In order to proceed with the calculations, it is necessary to know the resistance index of the walls. It differs depending on the type of material the building is made of.
Resistance (R) for houses made of ceramic bricks (with a masonry thickness of two bricks - 51 cm) is 0.73 ° C m² / W. The minimum thickness indicator at this value should be 138 cm. When using expanded clay concrete as the base material (with a wall thickness of 30 cm), R is 0.58 ° C m² / W with a minimum thickness of 102 cm. In a wooden house or a building made of timber with a wall thickness of 15 cm and a resistance level of 0.83 °C m²/W, a minimum thickness of 36 cm is required.
Building materials and their resistance to heat transfer
Based on these parameters, you can easily carry out calculations. You can find the resistance values in the reference book. In construction, bricks, log cabins made of timber or logs, foam concrete, wooden floors, ceilings are most often used.
Heat transfer resistance values for:
- brick wall (thickness 2 bricks) - 0, 4;
- log cabin (thickness 200 mm) - 0,81;
- log cabin (diameter 200 mm) – 0.45;
- foam concrete (thickness 300 mm) - 0.71;
- wood floor - 1, 86;
- ceiling ceiling – 1, 44.
Based on the above information, we can conclude that for the correct calculation of heat loss, only two quantities are required: the temperature difference indicator and the level of heat transfer resistance. For example, a house is made of wood (logs) 200 mm thick. Then the resistance is 0.45 °C m²/W. Knowing these data, you can calculate the percentage of heat loss. For this, a division operation is carried out: 50/0, 45=111, 11 W/m².
Calculation of heat loss by area is performed as follows: heat loss is multiplied by 100 (111, 11100=11111 W). Taking into account the decoding of the value (1 W=3600), we multiply the resulting number by 3600 J / h: 111113600=39, 999 MJ / h. With these simple mathematical operations, any owner can find out about the heat loss of his house in an hour.
Calculation of room heat loss online
There are many sites on the Internet that offer the service of online calculation of the heat loss of a building in real time. The calculator is a program with a special form to fill out, where you enter your data and after the automatic calculation you will see the result - a figure that will mean the amount of heat output from the dwelling.
Dwelling is a building in which people live during the entire heating season. As a rule, country houses where the heating system worksperiodically and as needed, do not belong to the category of residential buildings. In order to carry out re-equipment and achieve the optimal heat supply mode, it will be necessary to carry out a number of works and, if necessary, increase the power of the heating system. Such re-equipment can be delayed for a long period. In general, the whole process depends on the design features of the house and the indicators of increasing the power of the heating system.
Many have not even heard of the existence of such a thing as “heat loss at home”, and subsequently, having made a structurally correct installation of the heating system, they suffer all their lives from a lack or excess of heat in the house, not even realizing the true reason. That is why it is so important to take into account every detail when designing a home, to personally control and build, in order to ultimately get a high-quality result. In any case, the dwelling, no matter what material it is built from, should be comfortable. And such an indicator as the heat loss of a residential building will help make staying at home even more pleasant.
