Energy consumption optimization design method for building envelope structure suitable for cold region

Abstract

The invention relates to an energy consumption optimization design method of a building envelope structure suitable for a cold region, and relates to the technical field of building envelope structures in cold regions, the energy consumption optimization design method of the building envelope structure suitable for the cold region comprises the following steps: establishing a quantitative relation model between thermal performance of an envelope structure unit and building energy consumption, the change rule of the thermal performance of the enclosure structure unit is obtained; and establishing a thermal performance optimization model of the enclosure structure to obtain a calculation method for the economic thickness of the insulating layer of the non-transparent enclosure structure. The building envelope energy consumption optimization design method suitable for the cold region is provided for the first time, the standard requirement for saving energy by 75% can be met, and the method has great significance in formulating building design energy-saving technologies and building equipment energy-saving design technical measures suitable for climate characteristics and building load distribution characteristics of the cold regions such as Quzhou and the like.

Description

Technical Field

[0001] The invention relates to the technical field of cold-region building envelope structures, and in particular to an energy consumption optimization design method for building envelope structures suitable for cold regions. Background Art

[0002] At present, building energy consumption accounts for about 28% of the total social energy consumption, and is still increasing at a rate of 1 percentage point per year. In the future, the proportion of building energy consumption will rise to about 35%. Moreover, buildings consume 50% of the world's energy during their construction and use, light pollution, air pollution, electromagnetic pollution, etc. related to buildings account for 34%, construction waste accounts for 40% of the total waste, and greenhouse gas emissions account for about 30% of the total emissions. Achieving energy conservation and emission reduction in the construction field has very important economic and social benefits.

[0003] In recent years, with the continuous development of my country's building energy conservation, the country has basically achieved the goal of 50% and 65% energy conservation in buildings. The current national "Design Standard for Energy Conservation of Residential Buildings in Severe Cold and Cold Regions" (JGJ 26-2018) has raised the building energy conservation standard to 75%. The standard was implemented on August 1, 2019. It can be seen that it is imperative to implement the 75% building energy conservation standard nationwide in the future. However, the technical route for the 75% building energy conservation standard in cold regions such as Xuzhou is still in the exploration and demonstration stage, and no relevant technical reports have been seen. Summary of the invention

[0004] In order to solve the above problems, the present invention provides an energy consumption optimization design method for building envelope structures suitable for cold regions.

[0005] The present invention provides an energy consumption optimization design method for building envelope structures applicable to cold regions, and the energy consumption optimization design method for building envelope structures applicable to cold regions comprises the following steps:

[0006] Establish a quantitative relationship model between the thermal performance of the envelope structure unit and the building energy consumption, and obtain the changing law of the thermal performance of the envelope structure unit;

[0007] Establish a thermal performance optimization model for building envelopes and obtain a method for calculating the economic thickness of the insulation layer of non-transparent building envelopes;

[0008] According to the economic thickness calculation method of the thermal insulation layer of the non-transparent enclosure structure, the optimal conditions for equal effective heat transfer coefficients of the non-transparent enclosure structure units when the overall thermal performance of the enclosure structure is optimal are derived, and the maximum energy saving rate calculation method and the optimal energy saving rate calculation method of the enclosure structure are obtained;

[0009] According to the calculation method of the maximum energy saving rate of the enclosure structure and the calculation method of the optimal energy saving rate of the enclosure structure, the variation law of the maximum energy saving rate of the enclosure structure with the thermal performance of the window and the fuel type and the variation law of the optimal energy saving rate of the enclosure structure with the thermal performance of the window and the fuel type are obtained;

[0010] According to the variation law of the maximum energy-saving rate of the envelope structure with the thermal performance of windows and fuel types, the variation law of the optimal energy-saving rate of the envelope structure with the thermal performance of windows and fuel types, and the variation law of the thermal performance of the envelope structure unit, the optimal performance index parameters of the envelope structure and the energy-saving proportions between the building envelope structure and building equipment are obtained.

[0011] Furthermore, the step of establishing a quantitative relationship model between the thermal performance of the envelope structure unit and the building energy consumption and obtaining the change law of the thermal performance of the envelope structure unit includes the following process:

[0012] Calculate the total heat consumption of the energy-saving benchmark building according to Formula 1;

[0013] According to Formula 2, calculate the total heat consumption of the enclosure structure after taking energy-saving measures;

[0014] Formula 1: Q H =86.4gHDD18g(K R F R +K W F W +K win F win +α FL g FL F FL );

[0015] Formula 2: Q H '=86.4gHDD18g(K' R F R +K′ W F W +K′ win F win +α FL gK′ FL F FL );

[0016] In the above formula: Q H , Q H ' is the total heat consumption of the energy-saving benchmark building and the building envelope after energy-saving measures are taken, kJ / a; HDD18 is the number of heating degree days, ℃·d; α FL K is the basement floor temperature difference correction coefficient; R , K W , K win , K FLare the heat transfer coefficients of the roof, exterior wall, exterior window, and basement ceiling of the energy-saving benchmark building, W / (m 2 ℃); F R 、F W 、F win 、F FL are the roof, exterior wall, exterior window and basement ceiling area of ​​the energy-saving benchmark building, m 2 ; K R ', K′ W , K′ win , K′ FL are the heat transfer coefficients of the roof, exterior wall, exterior window, and basement ceiling of the enclosure structure after energy-saving measures are taken, W / (m 2 ·℃).

[0017] Further, the K is calculated according to Formula 3, Formula 4 and Formula 5 respectively. R ', the K' W , and the K′ FL ;

[0018] The formula three:

[0019] The formula 4:

[0020] The formula five:

[0021] In the above formula: x, y, z are the insulation thickness of the roof, exterior wall, and basement ceiling, respectively, m; λ ins is the thermal conductivity of the insulation material, W / (m·℃); R R ,R W ,R FL are the thermal resistance of the roof, exterior wall, and basement ceiling except the insulation layer, (m 2 ·℃) / W.

[0022] Furthermore, the step of establishing a thermal performance optimization model for the enclosure structure and obtaining a method for calculating the economic thickness of the thermal insulation layer of the non-transparent enclosure structure includes the following process:

[0023] Calculate the initial investment cost of energy-saving measures for the enclosure structure according to Formula 6, which includes the cost of adding insulation layers to the roof, exterior walls and basement ceiling and the cost of using new energy-saving exterior windows;

[0024] Calculate the cost of adding insulation to the roof, exterior walls and basement ceiling and the cost of using new energy-saving exterior windows according to Formula 7, Formula 8, Formula 9 and Formula 10;

[0025] Calculate the total life cycle cost and the cost saved during the life cycle according to Formula 11 and Formula 12 respectively;

[0026] Calculate the present value coefficient according to Formula 13, and obtain the objective functions Min and Max of the insulation layer thickness optimization model;

[0027] According to Formula 14 and Formula 15, calculate the annual heating operation cost of energy-saving buildings and the annual saving of operation cost of energy-saving buildings compared with the benchmark buildings respectively;

[0028] Formula 6: P(x, y, z) = P R +P W +P win +P FL ;

[0029] Formula 7: P R =xgF R C ins +F R C CR ;

[0030] Formula 8: P W =ygF W C ins +F W C CW ;

[0031] Formula 9: P FL =zgF FL C ins +F FL C CFL ;

[0032] Formula 10: P win =F win C win ;

[0033] Formula 11: LCC(x, y, z) = PWF·C′ H +P;

[0034] Formula 12: LCS(x, y, z) = PWF·ΔC H -P;

[0035] The formula thirteen:

[0036] Min:LCC(x,y,z)=PWF·C′ H +P;

[0037] Max: LCS(x, y, z) = PWF·ΔC H -P;

[0038] The formula fourteen:

[0039] The formula 15: In the above formula: P is the initial investment cost of energy-saving measures for the enclosure structure, yuan; P R , P W , P FL are the initial investment costs of adding insulation layers to the roof, exterior wall and basement ceiling, RMB; P win is the cost of the new exterior windows, RMB; C ins , unit price of thermal insulation materials, yuan / m 3 ; C CR , C CW , C CFL The unit prices of auxiliary materials and labor costs for the roof, exterior wall, and basement ceiling insulation layers are RMB / m 2 ; C win , unit price of new energy-saving exterior windows, yuan / m 2 ; LCC is the total life cycle cost, RMB; LCS is the cost saved during the life cycle, RMB; C′ H is the annual operation cost of energy-saving building heating, RMB / year; ΔC H is the annual operating cost saved by the energy-saving building compared with the benchmark building, RMB / year; PWF is the present value factor; Ne is the life cycle analysis period, years; d is the market discount rate; i is the energy price increase rate; η1 is the heat source efficiency of the heating system; η2 is the pipeline transmission efficiency; q feul The lower calorific value of the fuel per unit, kJ / kg or kJ / m 3 ;c feul The price of unit fuel, RMB / kg or RMB / m 3 .

[0040] Furthermore, the step of establishing a thermal performance optimization model for the enclosure structure and obtaining a method for calculating the economic thickness of the thermal insulation layer of the non-transparent enclosure structure also includes the following process:

[0041] Assume that the energy-saving rate of the building envelope structure after taking energy-saving measures is β, and obtain the constraint conditions according to the formula 1 and the formula 2;

[0042] According to the objective function and constraints, an auxiliary function is established.

[0043] The partial derivatives of x, y, and z in the auxiliary function are calculated and made zero, and then combined with the constraint conditions to obtain Formula 16, Formula 17, and Formula 18 for respectively calculating the thickness of the insulation layer of the roof, the exterior wall, and the basement top plate;

[0044] According to Formula 16, Formula 17 and Formula 18, Formula 19 is obtained;

[0045] According to Formula 19, Formula 3, Formula 4 and Formula 5, Formula 20 and Formula 21 are obtained;

[0046] According to the formula 20, when the energy-saving target is certain, the best combination of thermal performance of energy-saving building envelope structure is: the effective heat transfer coefficients of the roof, exterior wall and basement ceiling are equal; the effective heat transfer coefficient of the envelope structure unit that is not in direct contact with the outdoor atmosphere is equal to the heat transfer coefficient multiplied by the square root of the temperature difference correction coefficient;

[0047] Said

[0048] The constraint condition: ΔQ f (x,y,z)=K R 'gF R +K W 'gF W +K FL 'gαgF FL +K win 'gF win

[0049] -(1-β)g(K R F R +K W F W +K win F win +α FL g FL F FL )=0.

[0050] The auxiliary function: or

[0051] The formula sixteen:

[0052] The formula seventeen:

[0053] The formula eighteen:

[0054] The formula nineteen:

[0055]

[0056] The formula 20:

[0057] The formula 21: Q H '=86.4gHDD18g(1-β)g(KR F R +K W F W +K win F win +αgK FL F FL ), is the total heat consumption of the energy-saving building envelope, Q WIN '=86.4gHDD18gF win g win ', which is the heat consumption caused by the exterior windows of energy-saving buildings.

[0058] Furthermore, according to the economic thickness calculation method of the thermal insulation layer of the non-transparent enclosure structure, the optimal conditions for equal effective heat transfer coefficients of the non-transparent enclosure structure units when the overall thermal performance of the enclosure structure is optimal are derived, and the steps of obtaining the maximum energy saving rate calculation method and the optimal energy saving rate calculation method of the enclosure structure include the following process:

[0059] When the heat transfer through the roof, exterior wall and basement ceiling is zero, the maximum energy saving rate β of the enclosure structure is calculated by the formula 21. max Calculation formula 22;

[0060] Substitute the above formula 14, the above formula 16, the above formula 17 and the above formula 18 into the above formula 11, and take the derivative of β, and set the derivative equal to zero to obtain the optimal energy saving rate β of the enclosure structure. opt Calculation formula 23;

[0061] The formula 22:

[0062] The formula 23:

[0063]

[0064] Furthermore, the energy consumption optimization design method of the building envelope structure is applicable to the 75% energy saving standard requirement proposed in JGJ 26-2018 "Energy-saving Design Standard for Residential Buildings in Severely Cold and Cold Regions".

[0065] Furthermore, the reasonable proportion of the building envelope and building equipment that meet the 75% energy saving standard proposed in JGJ 26-2018 "Energy Saving Design Standard for Residential Buildings in Severe Cold and Cold Regions" should be: the structure shall bear 38% of the energy saving, and the rest shall be borne by the building equipment system; the thermal performance requirements of the envelope structure that meets the 75% energy saving standard proposed in JGJ 26-2018 "Energy Saving Design Standard for Residential Buildings in Severe Cold and Cold Regions" are as follows: the heat transfer coefficient of windows is 1.5W / ㎡.℃, the heat transfer coefficient of roof and exterior walls is 0.38W / ㎡.℃, and the heat transfer coefficient of basement floor is 0.44W / ㎡.℃.

[0066] The above technical solution provided by the embodiment of the present invention has at least the following advantages compared with the prior art:

[0067] The embodiment of the present invention provides an energy consumption optimization design method for building envelope structures suitable for cold regions. The present invention proposes for the first time an energy consumption optimization design method for building envelope structures suitable for cold regions, which can meet the standard requirement of 75% energy saving and has important significance for formulating building design energy-saving technology and building equipment energy-saving design technical measures suitable for the climate characteristics and building load distribution characteristics of cold regions such as Xuzhou. Specifically:

[0068] (1) The present invention establishes a quantitative relationship model between the thermal performance of the building envelope structure units such as the exterior walls, roofs, basement floors and windows of residential buildings and the building energy consumption, and obtains the variation law of the residential building energy consumption with the thermal performance of the exterior walls, roofs, basement floors and windows;

[0069] (2) The present invention establishes a thermal performance optimization model for the building envelope, obtains a method for calculating the economic thickness of the insulation layer of the non-transparent building envelope, and derives the optimal conditions for the effective heat transfer coefficients of the non-transparent building envelope units to be equal when the overall thermal performance of the building envelope is optimal; a calculation model for the maximum energy-saving rate and the optimal energy-saving rate of the building envelope for residential buildings is proposed, and the variation patterns of the two with the thermal performance of the windows and the fuel type are studied and analyzed;

[0070] (3) According to the variation law of the effective heat transfer coefficient of the building envelope when the best energy saving rate is achieved and the calculation method of the energy saving rate in cold areas, the present invention proposes a reasonable proportion of the building envelope and building equipment that should be shared to meet the 75% energy saving standard requirement. The building envelope is responsible for 38% of the energy saving, and the rest is borne by the building equipment system. The thermal performance requirements of the building envelope are as follows: the heat transfer coefficient of the window is 1.5W / ㎡.℃, the heat transfer coefficient of the roof and exterior wall is 0.38W / ㎡.℃, and the heat transfer coefficient of the basement floor is 0.44W / ㎡.℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0072] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0073] Figure 1 This is a graph showing the relationship between the maximum energy saving rate of the enclosure structure and the heat transfer coefficient of the external window in an embodiment of the present invention.

[0074] Figure 2 This is a graph showing the optimal energy saving rate of the enclosure structure in an embodiment of the present invention as the heat transfer coefficient of the window changes. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0076] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. At the same time, the steps and parameters involved, unless otherwise specified or specified, can be carried out according to the technical content disclosed in the prior art or directly using existing equipment, and the present invention document will not repeat them one by one.

[0077] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0078] Example

[0079] This example provides an energy consumption optimization design method for building envelope structures in cold regions. Taking Xuzhou as an example, it can meet the 75% energy saving standard requirements proposed in JGJ 26-2018 "Energy-saving Design Standard for Residential Buildings in Severely Cold and Cold Regions". The specific steps are as follows:

[0080] 1. Optimization model of thermal performance index of enclosure structure

[0081] 1.1. Calculate the heat consumption of the enclosure structure

[0082] For residential buildings with basements, the heat consumption of the envelope structure is composed of the heat consumption of the roof, exterior walls, exterior windows and basement ceiling. In cold and extremely cold areas, according to the "Code for Thermal Design of Civil Buildings (GB 50176-2016)", the thermal performance of the envelope structure should mainly meet the winter insulation requirements. Therefore, the thermal performance indicators of the envelope structure can be optimized according to the winter heat consumption. According to the "Code for Design of Heating, Ventilation and Air Conditioning of Civil Buildings (GB50736-2012)", the heat consumption of the envelope structure in winter is calculated according to the steady-state method. Therefore, the heat consumption of the building envelope structure can be calculated using the heating degree-day method according to the following formula:

[0083] Q=86.4gHDD18g(K R F R +K W F W +K win F win +α FL g FL F FL ), recorded as (3-1); where:

[0084] Q, total heat consumption of building envelope, kJ / a; HDD18, heating degree days, ℃·d; α FL Basement floor temperature difference correction factor; K R , K W , K win , K FL are the heat transfer coefficients of roof, exterior wall, exterior window and basement ceiling, W / (m 2 ℃); F R 、F W 、F win 、F FL are the roof, exterior wall, exterior window and basement ceiling areas, m 2 .

[0085] 1.2. Calculate energy savings

[0086] The total heat consumption of the building envelope structure for energy-saving benchmark buildings and after taking energy-saving measures can be calculated by the following formula:

[0087] Q H =86.4gHDD18g(K R F R +K W F W +K win F win +α FL g FL F FL ), recorded as (3-2);

[0088] Q H '=86.4gHDD18g(K' R F R +K′ W F W +K′ win F win +α FL gK′ FL F FL ), recorded as (3-3);

[0089] Where: Q H , Q H ' are the total heat consumption of the energy-saving benchmark building and the building envelope after energy-saving measures are taken, kJ / a; K R ', K′ W , K′ win , K′ FL are the heat transfer coefficients of the roof, exterior wall, exterior window, and basement ceiling after energy-saving measures are taken, W / (m 2 ·℃).

[0090] The heat transfer coefficients of the insulated roof, exterior wall and basement ceiling can be calculated according to formulas (3-4), (3-5) and (3-6) respectively:

[0091] (3-4):

[0092] (3-5):

[0093] (3-6):

[0094] Where: x, y, z are the thickness of the insulation layer of the roof, exterior wall, and basement ceiling, respectively, m; λ ins -Thermal conductivity of insulation material, W / (m·℃); R R ,R W ,R FL are the thermal resistance of the roof, exterior wall, and basement ceiling except the insulation layer, (m 2 ·℃) / W.

[0095] 1.3. Optimization of insulation layer thickness model

[0096] 1.3.1 Initial investment cost of enclosure structure

[0097] The initial investment cost of energy-saving measures for the enclosure structure includes the cost of adding insulation layers to the roof, exterior walls and basement ceiling and the cost of using new energy-saving exterior windows, which can be calculated as follows:

[0098] P(x,y,z)=P R +PW +P win +P FL , recorded as (3-7);

[0099] Where: P, initial investment cost of energy-saving measures for enclosure structure, yuan; P R , P W , P FL are the initial investment costs of adding insulation layers to the roof, exterior wall and basement ceiling, RMB; P win The cost of the new exterior windows is RMB. The investment cost of the insulation layer of the roof, exterior walls and basement ceiling and the cost of the exterior windows can be calculated according to formulas (3-8), (3-9), (3-10) and (3-11) respectively:

[0100] (3-8): P R =xgF R C ins +F R C CR ;

[0101] (3-9): P W =ygF W C ins +F W C CW ;

[0102] (3-10): P FL =zgF FL C ins +F FL C CFL ;

[0103] (3-11): P win =F win C win ;

[0104] Where: C ins , unit price of thermal insulation materials, yuan / m 3 ; C CR , C CW , C CFL The unit price of auxiliary materials and labor costs for the roof, exterior wall, and basement ceiling insulation layer, RMB / m2; C win , unit price of new energy-saving exterior windows, yuan / m 2 .

[0105] 1.3.2 Optimization Model

[0106] 1) Objective function

[0107] The energy-saving building scheme with the lowest life cycle cost is the best energy-saving building scheme. The initial investment cost of energy-saving measures for the enclosure structure can be calculated using formula (3-7), and the life cycle cost and cost savings during the life cycle can be calculated using formula (3-12) and formula (3-13) respectively:

[0108] (3-12): LCC(x,y,z)=PWF·C′ H +P;

[0109] (3-13): LCS(x,y,z)=PWF·ΔC H -P;

[0110] Then the objective function of the insulation layer thickness optimization model is:

[0111] Min: LCC(x,y,z)=PWF·C′ H +P, recorded as (3-14);

[0112] Max: LCS(x,y,z)=PWF·ΔC H -P, recorded as (3-15);

[0113] Where: LCC, life cycle cost, yuan; LCS, cost saved during the life cycle, yuan; C′ H , annual operation cost of energy-saving building heating, yuan / year; ΔC H , the annual operating cost saved by energy-saving buildings compared with benchmark buildings, yuan / year; PWF, present value factor, is calculated according to the following formula (3-16):

[0114] (3-16):

[0115] Where: Ne, life cycle analysis period, years; d, market discount rate; i, energy price increase rate; η1, heating system heat source efficiency; η2, pipeline network transmission efficiency; q feul , lower calorific value per unit of fuel, kJ / kg or kJ / m 3 ;c feul , unit fuel price, RMB / kg or RMB / m 3 .

[0116] The annual heating operating cost of energy-saving buildings and the annual operating cost savings of energy-saving buildings compared to benchmark buildings are calculated according to formula (3-17) and formula (3-18) respectively:

[0117] (3-17):

[0118] (3-18):

[0119] 2) Constraints

[0120] Assume that the energy-saving rate of the building envelope structure after taking energy-saving measures is β, Q H and Q H 'Calculate according to formula (3-2) and (3-3) respectively, then we have:

[0121] ΔQ f (x,y,z)=K R 'gF R +K W 'gF W +K FL 'gαgF FL +K win 'gF win

[0122] -(1-β)g(K R F R +K W F W +K win F win +α FL g FL F FL )=0, recorded as (3-19).

[0123] 1.3.3 Economic thickness of insulation layer

[0124] The optimization model of the economic thickness of the insulation layer of the building envelope is actually a conditional extreme value problem of a multivariate function, so the Lagrange multiplier method can be used to solve it. According to the objective function and constraints mentioned above, the following auxiliary function can be established:

[0125] Recorded as (3-20);

[0126] or: Recorded as (3-21);

[0127] in is the coefficient. Calculate the partial derivatives of x, y, and z of equation (3-20) or (3-21) and make them zero, and combine them with equation (3-19) to obtain:

[0128] Recorded as (3-22);

[0129] Recorded as (3-23); Recorded as (3-24);

[0130] The thickness of the insulation layer of the roof, exterior wall, and basement ceiling can be calculated by equations (3-22), (3-23), and (3-24). The present invention refers to this method as the Lagrange multiplier method. The economic thickness of the insulation layer of each enclosure structure is related to the heat transfer coefficient of the exterior window and the heat transfer coefficient of other enclosure structures. Therefore, it is not reasonable to determine the thickness of the insulation layer of the enclosure structure by only considering the heat transfer coefficient limit of the roof, exterior wall, and basement ceiling itself.

[0131] Formulas (3-22), (3-23) and (3-24) can be rearranged to obtain:

[0132] Recorded as (3-25);

[0133] Combining (3-4), (3-5), and (3-6), we have:

[0134] Recorded as (3-26);

[0135] From formula (3-26), it can be concluded that when the energy-saving target is certain, the best combination of thermal performance of energy-saving building envelope structure is: the effective heat transfer coefficients of the roof, exterior wall and basement ceiling are equal. The effective heat transfer coefficient of the envelope structure unit that is not in direct contact with the outdoor atmosphere is equal to the heat transfer coefficient multiplied by the square root of the temperature difference correction coefficient.

[0136] Take the reciprocal of each term in the above equation and multiply both the numerator and denominator on the right side by 86.4·HDD18 to obtain:

[0137] Recorded as (3-27);

[0138] Where Q H '=86.4gHDD18g(1-β)g(K R F R +K W F W +K win F win +αgK FL F FL ), is the total heat consumption of the energy-saving building envelope, Q WIN '=86.4gHDD18gF win g win ', which is the heat consumption caused by the exterior windows of energy-saving buildings.

[0139] In practical applications, as the target energy saving rate increases, the calculated value of the economic thickness of the insulation layer will become larger and larger, and will suddenly become negative after reaching a certain critical point. It can be seen from formula (3-27) that this is caused by the poor thermal insulation performance of the exterior windows selected for energy-saving buildings. When the heat transfer coefficient is too high, its heat consumption exceeds the heat consumption of the energy-saving building envelope structure at the target energy saving rate, and the numerator on the right side of formula (3-27) will become negative. At this time, the target energy saving rate cannot be achieved through the insulation of the envelope structure, and it is necessary to replace the exterior windows with better thermal performance to achieve the target.

[0140] 1.3.4 Maximum energy saving rate of enclosure structure

[0141] As mentioned above, as the target energy saving rate continues to increase, if the thermal performance of the windows of energy-saving buildings is not good enough (the heat transfer coefficient is large), the heat transfer loss through the windows will be higher than the heat transfer loss of the building's envelope, and the equivalent heat transfer coefficient calculated by formula (3-27) will be negative. In this case, the established energy saving rate cannot be achieved by increasing the thickness of the insulation layer of the envelope, and it is necessary to select windows with better thermal performance.

[0142] When the heat transfer through the roof, exterior wall and basement ceiling is zero, the maximum energy saving rate under a given state can be calculated by formula (3-27):

[0143] Recorded as (3-28);

[0144] 1.3.5 Optimal energy saving rate of enclosure structure

[0145] The economic insulation thickness of the non-transparent enclosure structure unit can be calculated by equations (3-22), (3-23) and (3-24) when the enclosure structure energy saving rate is constant. Substitute equations (3-17), (3-22), (3-23) and (3-24) into equation (3-12), and take the derivative of β, setting the derivative equal to zero, to obtain the optimal energy saving rate of the enclosure structure:

[0146] Recorded as (3-29);

[0147] From formula 3-29, we can see that β opt It is related to factors such as the thermal performance of the envelope structure unit of the benchmark building, the performance of the energy-saving building exterior windows, the thermal conductivity and price of the selected insulation materials, the type and price of fuel, and the performance of the heating system.

[0148] 2. Optimization of thermal performance indicators of enclosure structure

[0149] 2.1 Baseline Building Construction

[0150] Energy-saving buildings in my country's extremely cold and cold regions are calculated based on the heat consumption index of buildings with a general residential design of 1980-1981, 4 units and 6 floors, and a shape coefficient of about 0.30. The data after linear processing is used as the benchmark energy consumption. On the basis of this energy consumption value, the heating energy consumption of residential buildings is reduced by a certain proportion as the energy-saving target, and then energy-saving measures are proposed for building, thermal engineering, and heating design according to this target. Therefore, this study takes a specific building in Xuzhou City as the benchmark building model. The main body of the building adopts a frame structure, with 6 floors, a floor height of 3.0m, and a building area of ​​4426.74m 2 The insulation material is extruded polystyrene board with a thermal conductivity of 0.0345W / (m·℃). The basement ceiling temperature difference correction coefficient is 0.75. The areas of the roof, wall, external window and basement ceiling are 737.79m 2 、2566.74m 2 、570.3m 2 ,737.79m 2 The basic parameters of the enclosure structure are shown in Section 2.4. This example will analyze the economic thickness of the insulation layer and its influencing factors. The heating degree days HDD18 in Xuzhou is 2090 (d·℃), and the air conditioning degree days CDD26 is 137 (d·℃).

[0151] 2.2 Comparative analysis of economic efficiency of calculation results between limit method and Lagrange multiplier method

[0152] 1) Calculation results of the limit method

[0153] According to the Energy-saving Design Standard for Residential Buildings in Severely Cold and Cold Regions (JGJ26-2018), the thermal performance indicators of the enclosure structure units of each part of the energy-saving building are determined, as shown in Table 1. According to the commonly used exterior window types of buildings in Xuzhou, the exterior windows are replaced with 60 series casement plastic windows 5mm+15Ar+5mm, with a heat transfer coefficient of 2.2W / (m 2 ·℃), and substituting into formula (3-3~5), the thickness of the insulation layer of the roof, exterior wall, and basement ceiling are obtained as follows: x=0.105m, y=0.060m, z=0.059m, and the energy saving rate β is 78.45%.

[0154] Table 1

[0155]

[0156] 2) The calculation results of the Lagrange multiplier method in the present invention are used

[0157] The replacement windows are 60 series casement plastic windows 5mm+15Ar+5mm, with a heat transfer coefficient of 2.2W / (m 2·℃), and take the same energy saving rate β=78.45% as the limit method. According to formulas (3-22), (3-23) and (3-24), the thickness of the insulation layer of the roof, exterior wall and basement ceiling are obtained as follows: x=0.072m, y=0.066m, z=0.061m respectively.

[0158] 3) Comparison of economic efficiency between limit method and Lagrange multiplier method

[0159] According to the thickness of the insulation layer and the area of ​​each enclosure structure unit, the amount of insulation material used by the limit method and the Lagrange multiplier method can be calculated respectively. The calculation results are shown in Table 2.

[0160] Table 2 Comparison of economic efficiency between limit method and Lagrange multiplier method

[0161]

[0162] It can be seen that the limit method has certain shortcomings compared with the Lagrange multiplier method. Since it does not take into account the mutual constraints and influences between the enclosure structures, it causes a waste of investment. In actual engineering, in order to find the optimal insulation layer thickness, another method is to use energy consumption simulation software to simulate the investment cost of each part of the enclosure structure under various insulation layer thickness conditions, and then select the optimal solution with the lowest investment cost. However, this method requires a large number of simulation calculations, and the process is cumbersome. The Lagrange multiplier method can directly calculate and determine the insulation layer thickness of the enclosure structure, which greatly simplifies the calculation process.

[0163] 2.3 Maximum energy saving rate of enclosure structure

[0164] According to formula 3-28, the maximum energy saving rate of the enclosure structure can be calculated by selecting the type of window. The calculation results are shown in Table 3 and Figure 1 .

[0165] Table 3 Maximum energy saving rate of enclosure structure

[0166]

[0167]

[0168] 2.4 Optimal energy saving rate of enclosure structure

[0169] β opt It is related to the thermal performance of the envelope structure unit of the benchmark building, the performance of the exterior windows of the energy-saving building, the thermal conductivity and price of the selected insulation materials, the type and price of the fuel, the performance of the heating system, etc. The heating system uses natural gas and coal as fuel, and the main performance is shown in Table 4. The insulation material is XPS, and the main performance is shown in Table 5. The types and prices of exterior windows are shown in Table 6.

[0170] Table 4 Heating system performance

[0171]

[0172] Table 6 Heat transfer coefficient and price of rubber strip reinforced closed sliding window

[0173]

[0174]

[0175] According to formula 3-29, the optimal energy saving rate of the enclosure structure when the fuel type is coal and natural gas can be calculated, as shown in Tables 7, 8 and Figure 2 The corresponding LCC and LCS can be calculated according to formula (3-12) and formula (3-13) respectively. The life cycle is taken as 20 years, and the investment payback period is calculated based on the time when LCS is zero. The calculation results are shown in Table 7 and Table 8 respectively.

[0176] Table 7 Fuel type is coal

[0177]

[0178] Table 8 Fuel type is natural gas

[0179]

[0180]

[0181] From Tables 7 to 8 and Figure 2 The following conclusions can be drawn:

[0182] (1) The optimal energy saving rate of the enclosure structure decreases as the heat transfer coefficient of the window increases. To improve the optimal energy saving rate, external windows with good performance should be selected;

[0183] (2) When the best energy saving rate is achieved, the effective heat transfer coefficient of the enclosure structure has nothing to do with the best energy saving rate, but is related to the fuel type and insulation material type; the higher the fuel price, the smaller the effective heat transfer coefficient;

[0184] (3) When the fuel is coal, the life cycle cost of type III exterior windows is the lowest, and the optimal energy saving rate of the enclosure structure is 82.64%; when the fuel is natural gas, the life cycle cost of type IV exterior windows is the lowest, and the optimal energy saving rate of the enclosure structure is 86.80%.

[0185] 2.5 Optimal performance indicators of enclosure structures

[0186] As mentioned above, the optimal energy saving rate of the envelope structure is related to the type of windows, fuel type, insulation material type, etc. Different exterior windows and fuel types correspond to different optimal energy saving rates. At present, the energy saving rate of buildings in my country is calculated based on the heat consumption index of buildings with a general design of 1980-1981 residences in various places, 4 units and 6 floors, and a shape coefficient of about 0.30. The data after linear processing is used as the benchmark energy consumption. On the basis of this energy consumption value, the heating energy consumption of residential buildings is reduced by a certain proportion as the energy saving target, and then energy-saving measures are proposed for building, thermal engineering, and heating design according to this target. In the 1980s, the heating heat source in cold areas was mostly coal. When calculating the benchmark building energy consumption, the heat source efficiency was 0.55 and the pipeline transmission efficiency was 0.85. The average efficiency of coal-fired boilers is calculated by multiplying the rated efficiency by 0.9. The building energy saving ratio borne by the envelope structure when the coal-fired boiler takes the optimal energy saving rate of the envelope structure is calculated and shown in Table 9.

[0187] Table 9 Building energy saving ratio when the enclosure structure has the best energy saving rate

[0188] Window Type Optimal energy saving rate of building envelope The proportion of building energy saving undertaken by the building envelope Ⅰ 79.68％ 37.25％ Ⅱ 81.37％ 38.04％ Ⅲ 82.64％ 38.64％ Ⅳ 83.49％ 39.03％ Ⅴ 84.33％ 39.43％ Ⅵ 84.76％ 39.62％

[0189] Taking into account the minimum cost over the entire life cycle, the energy-saving thermal performance indicators of the enclosing structure should be selected according to the thermal performance indicators corresponding to the III external windows. The heat transfer coefficient of the external windows is 1.5W / (㎡.℃), the heat transfer coefficient of the external walls and roof is 0.38W / (㎡.℃), and the basement ceiling is 0.44W / (㎡.℃).

[0190] Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0191] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for optimizing the energy consumption of building envelope structures suitable for cold regions, characterized in that: The energy consumption optimization design method for building envelope structures suitable for cold regions comprises the following steps: Establish a quantitative relationship model between the thermal performance of the envelope structure unit and the building energy consumption, and obtain the changing law of the thermal performance of the envelope structure unit; Establish a thermal performance optimization model for building envelopes and obtain a method for calculating the economic thickness of the insulation layer of non-transparent building envelopes; According to the economic thickness calculation method of the thermal insulation layer of the non-transparent enclosure structure, the optimal conditions for equal effective heat transfer coefficients of the non-transparent enclosure structure units when the overall thermal performance of the enclosure structure is optimal are derived, and the maximum energy saving rate calculation method and the optimal energy saving rate calculation method of the enclosure structure are obtained; According to the calculation method of the maximum energy saving rate of the enclosure structure and the calculation method of the optimal energy saving rate of the enclosure structure, the variation law of the maximum energy saving rate of the enclosure structure with the thermal performance of the window and the fuel type and the variation law of the optimal energy saving rate of the enclosure structure with the thermal performance of the window and the fuel type are obtained; According to the variation law of the maximum energy-saving rate of the envelope structure with the thermal performance of windows and fuel types, the variation law of the optimal energy-saving rate of the envelope structure with the thermal performance of windows and fuel types, and the variation law of the thermal performance of the envelope structure unit, the optimal performance index parameters of the envelope structure and the energy-saving proportions between the building envelope structure and building equipment are obtained.

2. The method for optimizing the design of building envelope energy consumption suitable for cold regions according to claim 1 is characterized in that: The step of establishing a quantitative relationship model between the thermal performance of the envelope structure unit and the building energy consumption and obtaining the variation law of the thermal performance of the envelope structure unit comprises the following process: Calculate the total heat consumption of the energy-saving benchmark building according to Formula 1; According to Formula 2, calculate the total heat consumption of the enclosure structure after taking energy-saving measures; Formula 1: Q H =86.4gHDD18g(K R F R +K W F W +K win F win +α FL g FL F FL ); Formula 2: Q H '=86.4gHDD18g(K' R F R +K′ W F W +K′ win F win +α FL gK′ FL F FL ); In the above formula: Q H , Q H ' is the total heat consumption of the energy-saving benchmark building and the building envelope after energy-saving measures are taken, kJ / a; HDD18 is the number of heating degree days, ℃·d; α FL K is the basement floor temperature difference correction coefficient; R , K W , K win , K FL are the heat transfer coefficients of the roof, exterior wall, exterior window, and basement ceiling of the energy-saving benchmark building, W / (m 2 ℃); F R 、F W 、F win 、F FL are the roof, exterior wall, exterior window and basement ceiling area of ​​the energy-saving benchmark building, m 2 ; K R ', K′ W , K′ win , K′ FL are the heat transfer coefficients of the roof, exterior wall, exterior window, and basement ceiling of the enclosure structure after energy-saving measures are taken, W / (m 2 ·℃).

3. The method for optimizing the design of building envelope energy consumption suitable for cold regions according to claim 2 is characterized in that: Calculate K according to Formula 3, Formula 4 and Formula 5 respectively R ', the K' W , and the K′ FL ; The formula three: The formula 4: The formula five: In the above formula: x, y, z are the insulation thickness of the roof, exterior wall, and basement ceiling, respectively, m; λ ins is the thermal conductivity of the insulation material, W / (m·℃); R R ,R W ,R FL are the thermal resistance of the roof, exterior wall, and basement ceiling except the insulation layer, (m 2 ·℃) / W.

4. The method for optimizing the design of building envelope energy consumption suitable for cold regions according to claim 3 is characterized in that: The step of establishing a thermal performance optimization model for the enclosure structure and obtaining a method for calculating the economic thickness of the thermal insulation layer of the non-transparent enclosure structure comprises the following process: Calculate the initial investment cost of energy-saving measures for the enclosure structure according to Formula 6, which includes the cost of adding insulation layers to the roof, exterior walls and basement ceiling and the cost of using new energy-saving exterior windows; Calculate the cost of adding insulation to the roof, exterior walls and basement ceiling and the cost of using new energy-saving exterior windows according to Formula 7, Formula 8, Formula 9 and Formula 10; Calculate the total life cycle cost and the cost saved during the life cycle according to Formula 11 and Formula 12 respectively; Calculate the present value coefficient according to Formula 13, and obtain the objective functions Min and Max of the insulation layer thickness optimization model; According to Formula 14 and Formula 15, calculate the annual heating operation cost of energy-saving buildings and the annual saving of operation cost of energy-saving buildings compared with the benchmark buildings respectively; Formula 6: P(x, y, z) = P R +P W +P win +P FL ; Formula 7: P R =xgF R C ins +F R C CR ; Formula 8: P W =ygF W C ins +F W C CW ; Formula 9: P FL =zgF FL C ins +F FL C CFL ; Formula 10: P win =F win C win ; Formula 11: LCC(x, y, z) = PWF·C′ H +P; Formula 12: LCS(x, y, z) = PWF·ΔC H -P; The formula thirteen: Min:LCC(x,y,z)=PWF·C′ H +P; Max: LCS(x, y, z) = PWF·ΔC H -P; The formula fourteen: The formula 15: In the above formula: P is the initial investment cost of energy-saving measures for the enclosure structure, yuan; P R , P W , P FL are the initial investment costs of adding insulation layers to the roof, exterior wall and basement ceiling, RMB; P win is the cost of the new exterior windows, RMB; C ins , unit price of thermal insulation materials, yuan / m 3 ; C CR , C CW , C CFL The unit prices of auxiliary materials and labor costs for the roof, exterior wall, and basement ceiling insulation layers are RMB / m 2 ; C win , unit price of new energy-saving exterior windows, yuan / m 2 ; LCC is the total life cycle cost, RMB; LCS is the cost saved during the life cycle, RMB; C′ H is the annual operation cost of energy-saving building heating, RMB / year; ΔC H is the annual operating cost saved by the energy-saving building compared with the benchmark building, RMB / year; PWF is the present value factor; Ne is the life cycle analysis period, years; d is the market discount rate; i is the energy price increase rate; η1 is the heat source efficiency of the heating system; η2 is the pipeline network transmission efficiency; q feul The lower calorific value of the unit fuel, kJ / kg or kJ / m 3 ;c feul The price of unit fuel, RMB / kg or RMB / m 3 .

5. The method for optimizing the design of building envelope energy consumption suitable for cold regions according to claim 4 is characterized in that: The step of establishing a thermal performance optimization model for the enclosure structure and obtaining a method for calculating the economic thickness of the thermal insulation layer of the non-transparent enclosure structure is also The process includes: Assume that the energy-saving rate of the building envelope structure after taking energy-saving measures is β, and obtain the constraint conditions according to the formula 1 and the formula 2; According to the objective function and constraints, an auxiliary function is established. The partial derivatives of x, y, and z in the auxiliary function are calculated and made zero, and then combined with the constraint conditions to obtain Formula 16, Formula 17, and Formula 18 for respectively calculating the thickness of the insulation layer of the roof, the exterior wall, and the basement top plate; According to Formula 16, Formula 17 and Formula 18, Formula 19 is obtained; According to Formula 19, Formula 3, Formula 4 and Formula 5, Formula 20 and Formula 21 are obtained; According to the formula 20, when the energy-saving target is certain, the best combination of thermal performance of energy-saving building envelope structure is: the effective heat transfer coefficients of the roof, exterior wall and basement ceiling are equal; the effective heat transfer coefficient of the envelope structure unit that is not in direct contact with the outdoor atmosphere is equal to the heat transfer coefficient multiplied by the square root of the temperature difference correction coefficient; Said The constraint condition: ΔQ f (x,y,z)=K R 'gF R +K W 'gF W +K FL 'gαgF FL +K win 'gF win -(1-β)g(K R gF R +K W gF W +K win gF win +α FL gK FL gF FL )=0。 The auxiliary function: or The formula sixteen: The formula seventeen: The formula eighteen: The formula nineteen: The formula 20: The formula 21: Q H '=86.4gHDD18g(1-β)g(K R F R +K W F W +K win F win +αgK FL F FL ), is the total heat consumption of the energy-saving building envelope, Q WIN '=86.4gHDD18gF win g win ', which is the heat consumption caused by the exterior windows of energy-saving buildings.

6. The method for optimizing the design of building envelope energy consumption suitable for cold regions according to claim 5 is characterized in that: According to the economic thickness calculation method of the thermal insulation layer of the non-transparent enclosure structure, the steps of deriving the optimization conditions for equal effective heat transfer coefficients of the non-transparent enclosure structure units when the overall thermal performance of the enclosure structure is optimal, and obtaining the maximum energy saving rate calculation method of the enclosure structure and the optimal energy saving rate calculation method of the enclosure structure include the following processes: When the heat transfer through the roof, exterior wall and basement ceiling is zero, the maximum energy saving rate β of the enclosure structure is calculated by the formula 21. max Calculation formula 22; Substitute the above formula 14, the above formula 16, the above formula 17 and the above formula 18 into the above formula 11, and take the derivative of β, and set the derivative equal to zero to obtain the optimal energy saving rate β of the enclosure structure. opt Calculation formula 23; The formula 22: Formula 23:

7. The method for optimizing the design of building envelope energy consumption suitable for cold regions according to any one of claims 1 to 6, characterized in that: The energy consumption optimization design method of the building envelope structure is applicable to the 75% energy saving standard requirement proposed in JGJ 26-2018 "Energy-saving Design Standard for Residential Buildings in Severely Cold and Cold Regions".

8. The method for optimizing the design of building envelope energy consumption suitable for cold regions according to claim 7 is characterized in that: The reasonable proportion of the building envelope and building equipment that meet the 75% energy saving standard proposed in JGJ 26-2018 "Energy Saving Design Standard for Residential Buildings in Severe Cold and Cold Regions" is: the structure is responsible for 38% of the energy saving, and the rest is borne by the building equipment system; the thermal performance requirements of the envelope structure that meets the 75% energy saving standard proposed in JGJ 26-2018 "Energy Saving Design Standard for Residential Buildings in Severe Cold and Cold Regions" are as follows: the heat transfer coefficient of windows is 1.5W / ㎡.℃, the heat transfer coefficient of roof and exterior walls is 0.38W / ㎡.℃, and the heat transfer coefficient of basement floor is 0.44W / ㎡.℃.

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