Method for determining optimal heat transfer coefficient of super low energy consumption building envelope

Abstract

This invention proposes a method for determining the optimal heat transfer coefficient of the building envelope for ultra-low energy consumption buildings. The specific steps include: 1. Establishing a design building model based on the target project content, performing calculations and simulations to obtain the energy-saving rate of the design building under different scenarios; 2. Deriving a multiple linear regression formula for the building energy-saving rate E based on the simulation results; 3. Calculating the incremental investment coefficient resulting from the improvement in the unit heat transfer coefficient of the building's exterior walls, roof, and windows; 4. Obtaining and comparing the correlation coefficient of the energy-saving rate of each part with the incremental investment coefficient to determine the optimal cost-effective part of the target building; 5. Assigning values ​​to other parameters to determine the specific values ​​of the optimal cost-effective part of the target building; and obtaining the heat transfer coefficient of the optimal cost-effective part; 6. Based on the specific values, determining the optimal heat transfer coefficient scheme for the ultra-low energy consumption building envelope. This method avoids the problem of simply piling up various energy-saving technologies and can guide the decision-making of energy-saving technology schemes in the design stage of ultra-low energy consumption buildings. It is used to optimize the design of building envelope structures and scientifically improve the thermal performance of wall envelope structures.

Description

Technical Field

[0001] This invention belongs to the field of energy-saving building design technology, and in particular relates to a method for determining the optimal heat transfer coefficient of the external envelope of an ultra-low energy consumption building. Background Technology

[0002] With the increasing prominence of energy and environmental issues, "developing energy-efficient buildings" is not only a necessity for energy conservation but also a necessity for human health. Ultra-low energy buildings originated in Germany and are characterized by their excellent thermal insulation performance and ultra-high airtightness. They are dedicated to optimizing the design of building envelopes and scientifically improving the thermal performance of wall envelopes.

[0003] To achieve the required thermal insulation performance of ultra-low energy buildings, it is not necessary to blindly increase the thickness of the external envelope insulation. Optimization of the envelope structure is crucial, but this optimization should not be achieved by simply increasing its thickness. When determining appropriate thermal parameters for the external envelope, prediction and evaluation should be conducted first. Current energy-saving design standards include methods for evaluating the thermal performance of the building envelope; however, for designers, determining the specific optimization content for each part of the building envelope and judging the cost-effectiveness of each optimization remains challenging. Therefore, establishing a method for determining the optimal heat transfer coefficient of the external envelope will be of significant reference value in selecting optimization schemes for ultra-low energy building external envelopes. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a method for determining the optimal heat transfer coefficient of the building envelope for ultra-low energy consumption buildings. This method provides an objective evaluation approach for ultra-low energy consumption building envelope schemes, avoiding the simplistic application of various energy-saving technologies. It can guide decision-making regarding energy-saving technologies during the design phase of ultra-low energy consumption buildings. This method optimizes building envelope design, scientifically improves the thermal performance of the wall envelope, and creates a healthy and comfortable indoor thermal environment for residents while reducing energy consumption.

[0005] This invention discloses a method for determining the optimal heat transfer coefficient of an ultra-low energy consumption external envelope structure, comprising the following steps:

[0006] Step 1: Establish a design building model based on the target project content, and use energy consumption simulation software to perform multi-scenario calculations and simulations to obtain the energy-saving rate of the design building in different scenarios;

[0007] The multiple scenarios mentioned refer to exterior walls, roofs, and exterior windows;

[0008] Step 2: Based on multiple sets of simulation results, derive the multiple linear regression formula for the building energy efficiency rate E;

[0009] The formula is as follows:

[0010] E = aK1 + bK2 + cK3 + d

[0011] In the formula, E represents the energy efficiency of the designed building; K1, K2, and K3 represent the heat transfer coefficients of the exterior walls, roof, and windows of the designed building, respectively; a, b, and c are the correlation coefficients of the values ​​of K1, K2, and K3, respectively. absolute value The higher the value, the greater the impact of the corresponding K value on the energy saving rate. For example, in the formula, |a|>|b|>|c|, then the heat transfer coefficient K1 of the external wall corresponding to |a| has the greatest impact on the energy saving rate.

[0012] The error and accuracy of the regression formula depend on the number of scenarios designed in step one. The more scenarios, the smaller the error and the higher the accuracy. Generally, the number of scenarios should not be less than 3×3×3=27, with three sets of parameters for exterior walls, roofs, and windows.

[0013] Step 3: Calculate the incremental investment coefficient M resulting from the increase in the unit heat transfer coefficient of the building's exterior walls, roof, and windows. n Therefore, M n The calculation formula is:

[0014] M n =S n ×P n

[0015] In the formula, S n P represents the area occupied by this part in the target building project. n This indicates the price increase resulting from the improved heat transfer performance per unit area in the local market.

[0016] M n The size depends on: 1) the area occupied by this part in the target building project; 2) the price increase brought about by the performance improvement of this part in the local market.

[0017] The incremental investment coefficients M1, M2, and M3 resulting from the increase in the unit heat transfer coefficient of the building's exterior walls, roof, and windows are derived. Therefore, the total incremental investment is M.

[0018] M = M1K1 + M2K2 + M3K3

[0019] Step 4: Obtain the correlation coefficient of energy saving rate for each part. absolute value The ratios of |a|, |b|, and |c| to the incremental investment coefficient are compared to determine the optimal cost-effectiveness of the target building.

[0020] Step 5: Based on the obtained optimal cost-effectiveness location, assign values ​​to the other parameters in the building energy efficiency rate E regression formula, excluding the optimal cost-effectiveness location, to obtain the specific values ​​of the optimal cost-effectiveness location for the target building. The specific assignment process is as follows:

[0021] 1) For the parameters of the two parts other than the part with the best cost performance, the values ​​are taken as the compliance values ​​in the current ultra-low energy consumption standards of the region;

[0022] 2) The expected building energy efficiency rate E of the designed building shall be set at least to the standard value in the current ultra-low energy consumption building standard.

[0023] Substituting the assigned parameters into the formula E=aK1+bK2+cK3+d, the heat transfer coefficient of the part with the best cost performance can be obtained.

[0024] Step 6: Based on the specific values, derive the optimal heat transfer coefficient scheme for the ultra-low energy consumption outer envelope structure. The specific scheme is as follows:

[0025] 1) The part with the best cost-performance ratio is the value calculated in step five;

[0026] 2) Other parts are the recommended compliance values ​​in the current ultra-low energy consumption standards for this region.

[0027] The objectivity of the evaluation method for the optimal heat transfer coefficient of the ultra-low energy consumption outer envelope structure lies in:

[0028] In step one, a design building model is established based on the target project content. Different thermal parameters (heat transfer coefficients) of different building envelope parts are used in the design model to establish different scenarios. Parameters other than the building envelope heat transfer coefficient, such as building area and HVAC equipment, adopt the inherent parameters of the target building. The building envelope generally includes three parts: exterior walls, roof and exterior windows. Ultra-low energy consumption building simulation software, such as Tsinghua University's PHES ultra-low energy consumption simulation software, is used to calculate and simulate the various scenarios to obtain the energy-saving rate of the design building in different scenarios.

[0029] In step two, based on multiple simulation results obtained from the simulation software, the correlation between the building energy efficiency rate E and the heat transfer coefficients of the exterior walls, roof, and windows is determined. A multiple linear regression formula for the building energy efficiency rate E is then derived.

[0030] In step four, the correlation coefficients of energy-saving rates for each component and the ratios of incremental investment coefficients are obtained: |a| / M1, |b| / M2, and |c| / M3. These ratios represent the cost-effectiveness of improvements for different building envelope components. The higher the ratio, the more energy-saving targets for ultra-low energy consumption buildings can be achieved with less investment for that component. For example, if |a| / M1 > |b| / M2 > |c| / M3, it means that the cost-effectiveness of improvements for the exterior walls in the target project is the highest.

[0031] Step 5: Based on the optimal cost-effectiveness part obtained in Step 4, assign values ​​to the other parameters in the formula E = aK1 + bK2 + cK3 + d in Step 2, excluding the optimal cost-effectiveness part. The purpose of this step is to obtain the specific values ​​of the optimal cost-effectiveness part of the target building.

[0032] This invention proposes an objective evaluation method for the building envelope scheme of ultra-low energy consumption buildings, avoiding the problem of simply stacking thickness in the building envelope, and has important guiding significance for the decision-making of energy-saving technology schemes in the design stage of ultra-low energy consumption buildings. Attached Figure Description

[0033] Figure 1 Illustration of the process for confirming the optimal heat transfer coefficient of the external envelope structure. Detailed Implementation

[0034] The present invention is described in detail below through examples. These examples are merely illustrative and do not limit the scope of the invention. Based on the disclosure herein, those skilled in the art can make changes to the reagents, catalysts, and reaction process conditions within the scope of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

[0035] Although the invention has been shown and described with reference to specific embodiments, those skilled in the art will understand that various changes in form and detail may be made herein without departing from the spirit and scope of the invention as defined by the claims and their equivalents.

[0036] Taking the ultra-low energy consumption design of an office building in Huai'an, Jiangsu Province as an example, Huai'an is located in a hot-summer and cold-winter region in the Jiangsu thermal zoning. The building has six floors and a total construction area of ​​11,782 square meters. 2 The roof is flat, and the main functional and energy-consuming rooms are offices and meeting rooms.

[0037] Through modeling and simulation using energy consumption calculation software, the multiple linear regression formula for the building's energy saving rate E was obtained as follows:

[0038] E=-8.41K1-4.45K2-2.01K3+28.92

[0039] We can obtain |a| = 8.41, |b| = 4.45, and |c| = 2.01.

[0040] Calculate the incremental investment coefficient M resulting from the increase in the unit heat transfer coefficient of the building's exterior walls, roof, and windows. n In this project, the exterior wall area S1 = 4524m² 2 Roof area S2 = 2030m² 2 The area of ​​the exterior window wall, S3 = 1465m² 2 .

[0041] The project uses extruded polystyrene (XPS) board as insulation material. Based on the cost price of XPS board in the Huai'an market, the price increase per unit area for improving the heat transfer performance of the exterior walls is P1 = 97.5, the price increase for improving the heat transfer performance of the roof is P2 = 97.5, and the price increase for improving the heat transfer performance of the windows is P3 = 2000. Therefore, the incremental investment coefficients for exterior walls M1, roof M2, and windows M3 are 441090, 197925, and 2930000, respectively.

[0042] The correlation coefficient of energy saving rate and the ratio of incremental investment coefficient, |a| / M1, |b| / M2, and |c| / M3, are calculated as follows: |a| / M1 = 1.9 × 10 -5 |b| / M2=2.24×10 -5 |c| / M3=6.86×10 -7 .

[0043] Therefore, we can conclude that |b| / M2>|a| / M1>|c| / M3, and that the roof is the part of the target building with the best cost-performance ratio.

[0044] The building energy efficiency rate (E) and the heat transfer coefficients of the exterior walls and windows in the multiple linear regression formula for this project are assigned values ​​based on the limits in the current ultra-low energy consumption building standard. The energy efficiency rate (E) is set to 20%, the heat transfer coefficient of the exterior walls (K1) to 0.4, and the heat transfer coefficient of the exterior windows (K3) to 2.2. Substituting these values ​​into the equation...

[0045] E=-8.41K1-4.45K2-2.01K3+28.92

[0046] The roof heat transfer coefficient is 0.254.

[0047] Therefore, the final heat transfer coefficient scheme for the building envelope can be determined as follows: heat transfer coefficient K1 for the exterior wall is 0.4, heat transfer coefficient K2 for the roof is 0.254, and heat transfer coefficient K3 for the exterior window is 2.2.

[0048] By adopting this method, the project has conveniently and effectively derived a cost-effective design scheme for the building envelope of ultra-low energy consumption buildings, avoiding blind demonstration of the thickness of the insulation layer of the building envelope, and saving engineering costs while achieving the insulation performance of ultra-low energy consumption buildings.

Claims

1. A method for determining the optimal heat transfer coefficient of an ultra-low energy consumption external envelope structure, characterized in that, Includes the following steps: Step 1: Establish a design building model based on the target project content, and use energy consumption simulation software to perform multi-scenario calculations and simulations to obtain the energy-saving rate of the design building in different scenarios; the multi-scenario refers to the exterior walls, roof, and exterior windows; Step 2: Based on multiple sets of simulation results, derive the multiple linear regression formula for the building energy efficiency rate E, as follows: E = aK1 + bK2 + cK3 + d In the formula, E represents the energy saving rate of the designed building; K1, K2, and K3 represent the heat transfer coefficients of the exterior walls, roof, and windows of the designed building, respectively; and a, b, and c are the correlation coefficients of the values ​​of K1, K2, and K3, respectively. Step 3: Calculate the incremental investment coefficient M resulting from the increase in the unit heat transfer coefficient of the building's exterior walls, roof, and windows. n Therefore, M n The calculation formula is: M n =S n ×P n In the formula, S n P represents the area occupied by this part in the target building project. n This indicates the price increase in the local market resulting from the improved heat transfer performance per unit area of ​​this part; The incremental investment coefficients M1, M2, and M3 resulting from the increase in the unit heat transfer coefficient of the building's exterior walls, roof, and windows are derived. Therefore, the total incremental investment is M. M = M1K1 + M2K2 + M3K3 Step 4: Obtain the correlation coefficient of energy saving rate for each part. absolute value The ratios of |a|, |b|, and |c| to the incremental investment coefficient are compared to determine the optimal cost-effectiveness of the target building. Step 5: Based on the obtained optimal cost-effectiveness location, assign values ​​to the other parameters of the building energy efficiency rate E regression formula except for the optimal cost-effectiveness location to obtain the specific values ​​of the optimal cost-effectiveness location of the target building; substitute the assigned parameters into the formula E=aK1+bK2+cK3+d to obtain the heat transfer coefficient of the optimal cost-effectiveness location. Step 6: Based on the specific values, derive the optimal heat transfer coefficient scheme for the ultra-low energy consumption outer envelope structure.

2. The method for determining the optimal heat transfer coefficient of the ultra-low energy consumption outer envelope structure according to claim 1, characterized in that, The number of scenarios in the multi-scene setup should not be less than 3×3×3=27, with three sets of parameters for exterior walls, roofs, and windows.

3. The method for determining the optimal heat transfer coefficient of the ultra-low energy consumption outer envelope structure according to claim 1, characterized in that, In step five, other parameters are assigned values. The specific assignment process is as follows: 1) For the parameters of the two parts other than the part with the best cost performance, the values ​​are taken as the compliance values ​​in the current ultra-low energy consumption standards of the region; 2) The expected building energy efficiency rate E of the designed building shall be set at least to the standard value in the current ultra-low energy consumption building standard.

4. The method for determining the optimal heat transfer coefficient of the ultra-low energy consumption outer envelope structure according to claim 1, characterized in that, The optimal heat transfer coefficient scheme in step six is: 1) The part with the best cost-performance ratio is the value calculated in step five; 2) Other parts are the recommended compliance values ​​in the current ultra-low energy consumption standards for this region.

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