Intelligent building envelope structure with combined actuation using shape memory alloy springs

Abstract

In this self-adaptive building envelope structure design, a shape-memory alloy spring is used to automatically control the opening and closing of the structure based on temperature changes. The SMA spring shrinks in response to heat, opening the shell to limit sunlight exposure, while a normal spring closes the structure when the air cools. This passive system reduces energy consumption by allowing natural light in on cold days and shading the building on hot days without the need for electricity. Additionally, manual control is provided through low voltage electricity, eliminating the need for energy-consuming motors and sensors in active systems. Leveraging smart materials like shape-memory alloys, this design offers a cost-effective and energy-efficient solution for building envelopes.

Description

Intelligent Building Envelope Structure with Combined Actuation Using Shape Memory Alloy Springs

[0001] The optimal design of building exteriors is crucial due to the high cost of energy and the significant energy consumption of buildings. Poor design choices and lack of insulation lead to increased costs for maintaining ideal temperature levels inside buildings. Construction industry faces challenges in implementing complex building designs and avoiding thermal bridges, which increase energy consumption. Smart enclosure structures, in the form of building envelopes, or adjustable skins are important for reducing energy consumption. The invention aims to create a smart building shell that combines the benefits of active and passive systems. Users can control the structure as needed, while it can also operate automatically without sensors or electric motors. This self-adaptive structure can be easily installed on buildings without causing damage or excessive costs, helping to optimize energy consumption in both new and existing buildings.

[0002] F03G 7 / 06 – E04B 1 / 343

[0003] CN118148252

[0004] ULTRALOW-ENERGY-CONSUMPTION BUILDING ENVELOPE STRUCTURE

[0005] The invention relates to the technical field of constructional engineering, and discloses a building envelope structure with ultra-low energy consumption. A threaded sleeve is driven to slide by rotating a screw rod, so that supporting rods are driven by the threaded sleeve to be mutually staggered to support or pull back a second supporting plate, the second supporting plate is far away from or close to a first supporting plate to support a building, and the effect of conveniently adjusting the thickness of the building envelope structure is achieved; therefore, the mounting and dismounting efficiency is improved, and the practicability of the building envelope structure is improved; a clamping plate is extruded to drive a telescopic rod and a spring to contract inwards when a building is heated and expanded, and the telescopic rod and the spring are reset and rebound to drive the clamping plate to continue to be tightly attached to the building forwards when the building is cooled and contracted, so that the function of self-adaptive adjustment according to thermal expansion and cold contraction of the building is achieved, and the risk of building cracking is reduced; the service life of the building is prolonged.

[0006] This mentioned invention has similar energy optimization purposes as our claimed one, however, the design, process and method are different. For instance, while they both feature thermal adaptive structures, this one features sound insulation which is not part of our design. Moreover, ours utilizes shape memory alloy in the adjustable springs while this one makes no mention of such material.

[0007] CN115095042

[0008] FOLDING-LINE-SHAPED SELF-ADAPTIVE BUILDING ENVELOPE STRUCTURE

[0009] The invention discloses a broken-line-shaped self-adaptive building envelope structure, and belongs to the technical field of building energy. The broken-line-shaped heat collection wall is adopted, the surface area for absorbing sunlight is increased, the surface of the heat collection wall always has a small incident angle in one direction along with the change of the relative position of the sun, and therefore the solar energy utilization efficiency is high. The multiple phase change material packaging grooves which are mutually independent and adapt to the shape of the broken-line-shaped heat collection wall provide larger heat exchange areas for the phase change materials, the phase change materials are packaged respectively, sufficient phase change of the phase change materials is facilitated, and the heat storage and release capacity of the structure can be improved. Different working modes can be achieved through the airflow adjusting device, and the different working modes comprise indoor ventilation promotion in hot weather and indoor heating or indoor ventilation promotion in cold weather. According to the solar heat collecting wall, the convection heat exchange effect between air in the ventilating duct and the surface of the heat collecting wall can be enhanced, and the solar heat collecting wall has high sunlight absorptivity and keeps low emissivity at the same time.

[0010] This invention shares certain qualities with our claimed one in terms of minimizing energy consumption and offering a self-adaptive solution, but the designs and comprising elements of the two patents are different. For example, our design relies on shape memory alloy sprins while this one utilizes phase change materials.

[0011] CN212773743

[0012] SOLID-SOLID PHASE CHANGE CLIMATE SELF-ADAPTIVE ENCLOSURE STRUCTURE

[0013] The utility model relates to a solid-solid phase change climate self-adaptive enclosure structure which comprises a solid-solid phase change material with variable transparency, a high reflectivity film, a heat insulation layer, a right-angle fixing piece, bolts and nuts. The solid-solid phase change material is in a transparent state at high temperature in summer, and solar incident light is reflected into an outdoor environment under the action of the high-reflectivity film after penetrating through the solid-solid phase change material, so that heat of the heat insulation layer is reduced,and the heat insulation effect of the enclosure structure is realized; under low temperature in winter, the solid-solid phase change material is in an opaque state and can absorb and store incident light of the sun, the temperature of the enclosure structure is kept at a high level, and the effect of heat preservation of the enclosure structure is achieved. The building envelope structure is simple in structure and low in manufacturing cost, achieves active adjustment of solar radiation heat of the building envelope structure through combination of the solid-solid phase change material with the variable transparency and the high reflectivity film, and has the functions of heat preservation and heat insulation.

[0014] This invention aims to provide self-adaptive building enclosure similar to our claimed one which also functions based on solar heat to minimize energy consumption. However, the material, design and process as well as comprising elements are completely different. For instance, this one utilizes solid phase change material while ours emphasizes the use of shape-memory alloys.

[0015] United States Patent Application 20160123000

[0016] Building envelope solar heat and daylighting control system

[0017] A building envelope or cladding system which permits selective visibility from inside the building while rejecting solar heat and providing an optional insulative envelope. A vertical support mullion is on one side of a building structure. A module is attached to the mullion using a hinge, wherein the module is adapted to flip away from the mullion. A drive means includes a gear system housed within the module and a drive shaft connected through the building structure. One or more cladding elements is connected to and operable by the drive means. As a result, the cladding elements can both rotate and flip away to expose or cover an underlying glass surface. Each module is coupled to the drive means using a coupling assembly which is spring-biased to thereby rotate the cladding elements, thus modifying the effects of the sun and other ambient factors on the state of the building.

[0018] This mentioned patent involves a building envelope that allows heat and daylighting control which resembles our design in function. However, unlike this patent, ours focuses on energy optimization and provides a self-adaptive feature which makes both passive and active actuation possible.

[0019] In the case of the intelligent building envelope discussed, shape-memory alloy spring is utilized to control the opening and closing process of the structure. When exposed to heat, the SMA spring shrinks, automatically opening the shell to prevent excessive sunlight from entering the building. On the other hand, when the air cools down, a normal spring stores energy and closes the structure. This passive system allows for natural light to enter the building on cold days while shading it on hot days, reducing the need for active systems that consume electricity. This combined actuation system reduces energy consumption compared to traditional active systems that rely on electricity.

[0020] Moreover, the claimed structure not only addresses energy consumption issues in buildings but also offers manual control to users through low voltage electricity. During colder seasons, the normal spring closes the shell, while in warmer seasons, the shape-memory spring opens it. This solution eliminates the need for energy-consuming motors and sensors in active systems, while also providing manual control and flexibility as opposed to fully automatic passive systems. By leveraging smart materials like shape-memory alloys, this innovative design offers a cost-effective and energy-efficient solution for building envelopes.

[0021] The exterior of buildings has been very important for architects, as they have always tried to achieve the optimal temperature inside the building with the help of local materials and considering the climate. With the advancement of technology and the emergence of modern heating and cooling systems, many refused to be in harmony with nature and turned to unsustainable buildings. With the development of construction techniques, the energy consumption of buildings is optimized by using double-skinned or multi-layered facades.

[0022] But after the invention of the first smart materials and its commercialization in 1992, the design culture of building shells changed, and evolved in the form of layers of materials that were placed next to each other due to mechanical properties such as heat transfer coefficiency. Such designing choices had complicated and sometimes impractical details that were not considered. In fact, in the outer layer of the building the first and foremost important is the usage of smart materials with features that would perform well under different conditions. For example, the function of shape change, transparency change, concentration change, color change, etc. were among the factors that were considered in building shells.

[0023] Smart building envelopes were initially created in the form of active systems that functioned with the help of electric motors and light and temperature sensors and central control systems, etc., examples of which can be found in the Al Bahr Towers of the United Arab Emirates. Active skins are generally referred to as skins in which the ability to change the shape of the facade of the building is possible with the help of electric energy and electric motors, sensors, etc. One of the advantages of these shells is the 50% energy reduction in Al Bahr Building in Abu Dhabi, which is a practical example and winner of the innovation award in the design of sustainable buildings in 2012.

[0024] However, due to the need for electricity consumption to control these building shells, the maintenance issue which itself added to the energy consumption of the building. Therefore, engineers thought of designing passive shells with smart materials that functioned naturally and automatically based on their own drives and without the need for systems such as motors, sensors and central controllers. Instead these systems relied on natural elements to achieve efficient and cost-effective solutions. For example, the material designed from pine wood at the University of Stuttgart, Germany, which instinctively changes its shape due to the absorption of air moisture and controls the entry of light, is one of the latest examples of the passive shell of a building designed in 2015. The issue with these passive systems is that they took away the possibility of manual control from the user due to the automatic function and did not allow the external view to change according to the user's wishes. Another issue that should be considered in both groups is the extent of blocking the view to the outside of the building, because the shell should not only reduce the energy consumption of the building, but also in terms of aesthetics, it should not limit the view to the outside of the building.

[0025] Shape memory alloys or SMA are one of the most well-known examples of smart materials that have been widely used in the fields of medicine, construction and industrial design in the past eighty-five years since their discovery. Shape memory was first observed in 1932, in an alloy made of gold and cadmium, and later in 1938 in brass, and in 1962 an alloy of half titanium and half nickel was discovered, which was highly deformable. It is known as Nitinol, which is one of the most widely used smart materials. Other forms of smart materials with copper composition are known as CuZnAl, NiAl, FeMnSi. But it is necessary to mention that the highest amount of change in shape and performance is related to Nitinol. Nitinol can be programmed into two different modes based on the process by which it is produced.

[0026] The first form observed in Nitinol is the two-way shape memory effect. In this case, the material is transformed between two general structures, one is the memory given to it at high temperature and the other is the memory given to it at low temperature. At the memory temperature, the crystal structure of the alloy changes and this change shows itself in the form of volume change and shape change. The change of shape shows itself either in the form of widening and expansion, or in the form of shrinking and contraction. The two temperatures to which the material's shape memory is given are made possible by changing the ratio of the alloy composition. Nitinol can change shape at temperatures between -100 and +100 degrees Celsius.

[0027] Another form of memory alloys is one-way memory. In this case, the material has the ability to be flexible and bend or take a special shape. But as soon as heat or cold enters it - of course, the temperature that is desired and programmed to preserve the memory - it returns to the initial state in which it was created. Of course, this heat is created with the help of low voltage electricity inside the material, which creates the ability to return the form to the state it has in the original memory.

[0028] Among the significant beneficial properties of these materials are their superelastic properties. The very high tensile strength makes this material very practical. The ability to bend and stretch the memory alloy is much higher than stainless steel and does not undergo permanent deformation at very high tensions.

[0029] Considering the ever-increasing cost of energy carriers and the significant impact of the building sector, which accounts for 40% of the total annual energy consumption, the optimal design of the outer shell of buildings is very important. The design of buildings due to not observing the principles of design, not using insulation, following the design of buildings in styles such as all-glass towers, etc., annually incurs exorbitant costs to achieve the optimal temperature inside the buildings. The difficulty of implementation and the costliness of the reconstruction of the building body is another problem of the construction industry, the lack of accurate implementation of the details of the bodies, especially its complex details, causes the creation of thermal bridges during the construction of buildings, which consequently increases the energy consumption in construction. In this regard, the use of smart enclosure structures in buildings is very important to reduce energy consumption.

[0030] One of the goals of the invention is to achieve a smart shell that simultaneously benefits from the advantages of both active (Active Actuation) and passive (Passive Actuation) systems in building shells. On the one hand, like active systems, the shell has the ability to be controlled by the user so that the user can open or close the shell if needed, and on the other hand, like passive systems, the shell does not require sensors, electric motors, etc. It can operate automatically so that it can finally control and reduce more than both groups of building energy consumption. In addition, smart building envelopes should have the ability to be added to the body of the building in the form of inductive units and without the need for much damage and excessive costs, to be implemented on the facade of the building. Smart shells can be mass-produced and installed and implemented according to standards in order to optimize energy consumption not only in buildings under construction but also in completed buildings.Solution of Problem

[0031] Shape-memory alloys have been produced and used for decades, but the applications in the industry and the latent capacities are not fully known. By shaping the wire made of memory alloy into the shape of a spring and placing it at a temperature above 120 degrees Celsius, the wires become a shape-memory spring. The memory spring not only works like a spring, but in case of a change in shape or a lot of tension, it changes its shape with the help of ambient heat absorption or electric current and becomes the shape that was initially induced into it and has in the memory. In this case, it is the same spring.

[0032] The intelligent building envelope presented here, is made by using the function of the spring made of shape-memory alloy and the normal spring controls the opening and closing process of the building shell, as shown in. The shape-memory spring shrinks by absorbing the heat of the environment and automatically opens the shell and protects the building body so that the sun's rays do not penetrate too much into the interior spaces of the building in the summer.

[0033] As shown in, facing the memory spring, there is a normal spring, which, when the claimed structure is opened, stores the tensile energy, which causes the force of the normal spring to exceed the force of the spring when the air cools down. The shape-memory spring will prevail because it no longer absorbs heat and has lost its strength and is ready to change its shape temporarily, which results in the closing of the structure so that the sun's rays enter the interior and heat the air inside the building. As a result, this function automatically allows sunlight to enter the building on cold days and prevents light from entering the building with shading on hot days. This building shell also allows the user to open or close it based on personal taste with the help of electric current because the electric current generates heat inside the spring and encourages it to collapse and return to its original shape which is the spring and cause the opening of the shell.

[0034] The prototype of the claimed smart building shell structure is made with 4 shape-memory springs (Nickel-Titanium) or Nitinol (Nitinol) as shown in. The memory spring has a thickness of 0.75 mm and the ability to change the length up to 15 cm. In the original state, the shape-memory spring has a length of 2 cm. The outer diameter is 6.5 mm and the number of coils of the spring is 21. Facing this SMA spring is the normal spring which is 0.7 mm thick with 61 coils and the length is 4.30 cm in the normal state, which can be stretched 15 cm. The diameter of the normal spring is 6.20 mm. The strength of the springs is calculated using Hooke's formula F=-kx, where k is the constant of the spring and x is the amount of change in the size of the spring, which results in force or F.

[0035] The intelligent building envelope structure provides combined active and passive actuation via shape memory alloy (SMA) springs seeks to reduce the amount of energy consumption in the building. On the one hand, it addresses the technical problem of energy consumption in active systems that require the use of electricity to control electric motors and sensors and central control systems, etc., to open or close the shells. The usage of SMA springs makes for passive actuation and the regular springs aid in achieving combined mobility. This minimizes energy consumption that usually plagues the active actuation systems with unnecessary expenses and are not environmentally friendly.

[0036] Also, the problem with existing passive systems that operate completely automatically and do not allow manual control to the user is addressed with the help of a minimal low voltage current of electricity for when the user needs to open the structure. During colder seasons, the normal spring takes over the shape-memory spring and closes the shell. During warmer seasons, the process is reversed. This not only eliminates the process that required the consumption of electricity and electric motors in active systems by operating automatically, but also solves the problem of passive systems that cannot be controlled with the help of low voltage electricity.Therefore, the solution provided here resolves these issues by using smart materials like SMA springs and offering the combined actuation feature.Advantage Effects of the Invention

[0037] - Reducing cooling and heating energy consumption in the building.

[0038] - Ability to protect the exterior of the building in case of natural and unnatural complications.

[0039] - The low consumption of the combined mobility system is even more than the active smart shells due to the absence of electric motors, sensors, central control systems, etc., which themselves add to the energy consumption of the building.

[0040] - The ability to operate the shell automatically without the need for sensors and electric motors, etc.

[0041] - The ability to manually control the shell with the lowest amount of electric current, which creates heat in the shell and solves one of the main problems of passive shells, which is the user's lack of control over the movement of the shell.

[0042] - The ability to easily implement smart skins in the body of the building, not only in the buildings that are being implemented, but also in high-rise buildings, with the lowest cost as an induction unit on the facade. For example, it covers buildings whose main body is made of glass with an adaptable body to reduce energy consumption.

[0043] - No need for very high skill for execution, unlike many building details that consist of various layers of insulation and materials.

[0044] - The possibility of mass production in order to achieve standard high quality of execution in buildings.

[0045] - Not blocking the view of the building due to the ability to collapse, unlike many smart bodies that limit the observer's view.

[0046] Shows a general view of the claimed design.

[0047] Displays various angles of the claimed structure.

[0048] Captures a side view of the claimed design.

[0049] Depicts a view of the claimed structure as installed on the wall of a building.

[0050] Shows a general view of the structure and its components and the connection between its parts which are:

[0051] 1) 623zz ball bearing (40x)

[0052] 2) Standard tension spring (1x)

[0053] 3) M8 shaft (1x)

[0054] 4) Linear bearing LM8UU (1x)

[0055] 5) M3 nut (16x)

[0056] 6)M3x20 screw (16x)

[0057] 7) Shape memory alloy spring (4x)

[0058] Displays views of the claimed design from the top and in three dimensions, in both folded and opened form.

[0059] Captures a side view of the claimed structure wherein the placement of the springs can be seen in both closed and opened form:

[0060] A) The shape memory alloy (SMA) springs

[0061] B) The standard tension spring

[0062] The right side shows the shell is in a closed state, which occurs in cold weather, when the shape-memory spring loses its original shape and the normal spring overcomes it. The left side shows the shell is in an open state, which occurs in hot weather and casts a shadow on the facade. Due to the hot air, the shape-memory spring returns to its initial state, i.e., a compressed tension spring, by absorbing heat, and causes the shell to open and puts the normal spring in tension.

[0063] Depicts a view of the claimed structure as installed on the exterior wall of a building:

[0064] A) Metal anchors bolted into the wall to support the weight of the structure.

[0065] As depicted, the structure is installed at each level, using metal anchors, fastened where the connections and inner layers of the ceiling at each floor and its connectins are being constructed. The right side is when the weather is cold and the envelope is folded which allows sunlight to enter the building. The left side is when the weather is hot and the shell is opened so that the sun's rays do not enter the interior.Examples

[0066] The invention involves self-adaptive building shell structures or envelopes that utilize shape-memory alloys and springs in order to provide combined actuation features and minimize energy costs. The process of installing one such system on the exterior of a building includes the following:

[0067] 1- It is possible to install the claimed structure on the exterior of the building with the help of pre-defined bolts on the facade or metal anchors or screws to attach each block of the shell to the facade at each floor level.

[0068] 2- Connecting an electrical network (low voltage) to shape-memory springs for manual control if needed.

[0069] 3- Installing the desired outer shell on the base structure, which depending on the project can be made of different materials such as fiberglass, wood, etc.

[0070] The process of assembling the designed shell structure with combined actuation feature involves the following steps:

[0071] 1- Making the main joints with the help of plastic injection systems into molds or 3D printing

[0072] 2- Making shape-memory springs

[0073] 4- Making a normal spring

[0074] 5- Laser cutting of compressed plastic (plexiglass) or cutting of aluminum sheets or wood with the help of CNC cutting machine for the arms of the shell body according to the construction project

[0075] 6- Assembling the parts

[0076] The process of manufacturing the shape-memory alloy springs is comprised of the following phases:

[0077] 1- Using nitinol wire with the desired coefficient that depends on the specific climate of the region. The higher the titanium alloy, the lower the temperature at which the wire returns to its original memory. For example, in the built prototype, the desired temperature is more than 50 degrees Celsius, which can be used for extreme climates. Of course, the stored temperature of the shape-memory alloy can be reduced to 35 °C.

[0078] 2- Changing the shape of the wire into a spring form depending on the size of the modules and the required force, which determines the thickness, length and diameter of the spring.

[0079] 3- Heating the wire until it loses its original shape and remembers the shape of the spring with a temperature of more than 120 degrees Celsius.

[0080] This invention will be very widely used in construction projects of any capacity that are interested in cost-effective, environmentally friendly solutions. The measurements can be modified to fit any industrial or household needs and the installation process is flexible and straight forward. The manufacturing of the shape-memory alloys can be done to suit the needs of construction projects in residential or indusrial fields. The building envelope structure can be pre-made and installed on an existing building or be added to the site during the process of construction.

Claims

An intelligent building envelope structure with combined actuation using shape memory alloy springs that respond to weather conditions and minimize energy consumption. The design comprises:

1. A metal axis or shaft (aluminum)2. Two plastic joints located at the beginning and end of the aluminum axis (shaft)3. A linear ball bearing4. A shape memory alloy (SMA) spring5. A standard tension spring6. A folding body or shell7. Movable armsAccording to claim 1, the claimed structure features combined actuation, which includes both passive and active adaptive mobility for the folding and opening of the structure.According to claim 2, passive actuation is achieved by using shape-memory alloy spring which absorbs ambient heat and automatically retracts and opens the structure to prevent the building from receiving solar energy on hot days. In cold days, the corresponding standard spring takes over, retracts and closes the envelope.According to claim 2, the featured SMA spring can be modified to respond to any weather fluctuation and suit the temperatures of any region according to the construction project's needs.According to claim 2, active actuation is acheived with the help of a low voltage current of electricity inside the shape-memory alloy spring, which creates heat and makes it possible to manually control the opening and folding of the structure if needed.According to claim 1, the designed self-adaptive structure can be installed during or post construction without the need for sensors, electric motors or central control systems.

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