Of course, the main foci of heat loss in the house are doors and windows, but when viewing a picture through a thermal imager screen, it is easy to see that these are not the only sources of leakage. Heat is lost through an illiterate 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 heating option and carry out additional work on the insulation of the building. It is interesting that for each type of structure (from timber, logs, silicate or ceramic bricks), the level of heat loss will be different. Let's talk about this in more detail.
Basics of calculating 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 that can be analyzed thermally. The heat loss program at home in this case will not be of practical importance.
In order to conduct a full analysis, calculate heat-insulating materials and choose a heating system with optimal power, you need to have knowledge about real heat loss in a home. Walls, roofs, windows and floors are not the only foci of energy leakage from a home. Most of the heat leaves the room through improperly mounted ventilation systems.
Factors Affecting Heat Loss
The main factors affecting the level of heat loss are:
- High level of temperature difference between the indoor microclimate of the room and outdoor temperature.
- The nature of the thermal insulation properties of building envelopes, which include walls, ceilings, windows, etc.
Heat loss measurement values
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 the products. The value used to measure the thermal insulation properties is called heat transfer resistance. This indicator is responsible for reflecting the temperature difference during the passage of the nth amount of heat through a section of fencing structures with an area of 1 m 2. So, we will figure out how to calculate the heat loss at home.
The main values necessary for calculating heat loss at home include:
- q is a value indicating the amount of heat leaving the room outside through 1 m 2 of the barrier structure. Measured in W / m 2 .
- ∆T is the difference between the temperature in the house and on the street. Measured in degrees (° C).
- R is the heat transfer resistance. Measured in ° C / W / m² or ° C · m² / W.
- S is the area of the building or surface (used as needed).
The formula for calculating heat loss
The heat loss program at home is calculated according to a special formula:
R = ∆T / q
When calculating, remember that for structures consisting of several layers, the resistance of each layer is summed. So, how to calculate the heat loss of a frame house, bricked outside? 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. In reference books and manuals, it is always this reference value that 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 in the calculation, is carried out in several stages. The process requires special attention and concentration. Calculate heat loss in a private house in a simple way:
- Determined through the walls.
- Calculated through window structures.
- Through the doorways.
- Calculate through the overlap.
- The heat loss of a wooden house is calculated through the floor covering.
- Add the previously obtained values.
- Considering thermal resistance and energy loss through ventilation: from 10 to 360%.
For the results of paragraphs 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 guides 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 at a temperature difference for atypical rooms: corner and non-corner rooms, single and multi-story buildings.
The need to calculate heat loss
The 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 method of heating the room itself, should not be overlooked. While working on the construction of the house, a lot of time will have to be given not only to the design documentation, but also to the calculation of the heat loss of the house. If in the future you are going to work in the field of design, then the engineering skills for calculating heat loss will definitely be useful to you. So why not work out to do this work experimentally 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 your calculations. By calculating the heat loss indicator incorrectly, you run the risk of freezing in cold weather or exhausted by heat due to excessive heating of the room. It is necessary not only to choose the right device, but also to determine the number of batteries or radiators that can heat one room.
Estimation of heat loss by calculation example
If you do not need to study the calculation of heat loss at home in detail, we will dwell on the evaluation analysis and determination of heat loss. Sometimes in the process of calculation errors occur, so it is better to add a minimum value to the estimated power of the heating system. In order to start the calculations, you need to know the wall resistance index. 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 (with a wall thickness of 30 cm) as the base material, R is 0.58 ° · m² / W with a minimum thickness of 102 cm. In a wooden house or timber structure 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, it is easy to carry out calculations. You can find the resistance values in the directory. Most often used in construction are bricks, log houses made of timber or logs, foam concrete, wooden floors, and ceilings.
Heat transfer resistance values for:
- brick wall (thickness. 2 bricks) - 0.4;
- log house made of timber (thickness 200 mm) - 0.81;
- log cabin (with a diameter of 200 mm) - 0.45;
- foam concrete (thickness. 300 mm) - 0.71;
- wooden floor - 1.86;
- ceiling overlap - 1.44.
Based on the above information, we can conclude that for the correct calculation of heat loss, only two quantities will be 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 performed: 50 / 0.45 = 111.11 W / m².
Calculation of heat loss by area is performed as follows: heat loss is multiplied by 100 (111.11 * 100 = 11111 W). Taking into account the decoding of the value (1 W = 3600), the resulting number is multiplied by 3600 J / hour: 11111 * 3600 = 39.999 MJ / hour. Having performed such simple mathematical operations, any owner can learn about the heat loss of his house in an hour.
Calculation of heat loss in the room 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 in, where you enter your data and after automatically calculating, you will see the result - a figure that will mean the amount of heat output from the living room.
A residential building is a building in which they live throughout the entire heating season. As a rule, summer cottages, where the heating system operates periodically and if necessary, do not belong to the category of residential buildings. In order to carry out re-equipment and achieve an optimal heat supply mode, it is necessary to carry out a number of works and, if necessary, increase the capacity of the heating system. Such re-equipment can drag on for a long period. In general, the whole process depends on the design features of the house and indicators of increasing the power of the heating system.
Many did not even hear about the existence of such a thing as "heat loss at home", and subsequently, having made the structurally correct installation of the heating system, they suffer all their life from a lack or excess of heat in the house, without even realizing the true reason. That is why it is so important to consider every detail when designing a home, to engage in personal control and construction, in order to ultimately get a high-quality result. In any case, the home, regardless of what material it is built from, should be comfortable. And such an indicator as heat loss of a residential building will help make your stay at home even more pleasant.