Smart Shading

Shading element is one of the important components of the skin façade and the effectiveness of the building enclosure depends on the shading configuration of the entire system. However, the shading system increases the cost of the construction and maintenance; and in case of double skin façade it requires a wide cavity in order to contain the blades and a space for cleaning and maintaining these devices that make the Architects very careful before making a decision on using the shading in their design. One of the purpose of the double skin facade is to provide a shell for the shading elements especially in the high rise buildings where the wind add a significant load on the shading system otherwise a sturdy structure to protect the system should be used in case of using the single skin façade.

The traditional assumption that the facade should be static with rigid walls or curtain wall is no longer valid, the homeostatic facade examines the possibility of using a responsive system to the environment. With the emergence of smart shading, an interest in using creative building systems and the need to build durable double skin facade with dynamic elements, the building enclosure can be more sensitive to the environment.

Using Shape Memory Alloy as blinds is one of the ideas to create a shading system that react automatically with the temperature variance without the need of any mechanical equipment or power of any kind and the vent ratio and air flow is determined by the properties of the material. Each blind is composed of two separate layers of different metal joined together which expand at different rates as they are heated. Therefore, when they are heated one reacts more quickly and bends in one direction, then when they cool down they go back to their original position. Bi­metal is commonly used today in thermostats as a measurement and control system and in electrical controls as a component in mechanical systems therefore instead of using it as sensor that regulates the blinds opening why they cannot become the shading element itself. Nevertheless, we are talking about flexible and very thin strips, compared with the typical blinds that have firm structural frames. Therefore, using the bimetal blinds on the exterior face of the building façade make them vulnerable to the outside conditions. As a result we cannot think of this system without integrating it into a double skin facade.

Smart shading has many areas that can be developed depending on combining different technologies to achieve the goal of built an efficient building enclosure. New materials and different configurations can be tested that lead to alterna­tive connection details. Bimetal applications on the building façade and the DSF are both serve to create an interactive façade with the temperature changes as wells as the direction of the sunlight and since the external solar protections are more effective than internal shading devices. In the case of the double-skin facade, the bimetal sheets can be integrated in the cavity. It is thus protected from the bad weather and pollution. Solar protection can remain in place even in the event of important wind, which represents an undeniable advantage for DSF of the high rise buildings.

In the last years, more public interest in sustainable design, energy conservation and zero-emission building design has provoked the designers to find alternative solutions. With the revelation of new smart materials, the evolution of digital technologies and the availability of mass-customization methods, Reacting with outside temperatures, has the potential to develop self-actuating intake or exhaust for facades.

http://www.archdaily.com/101578/

AN INVISIBILITY CLOAK FOR SEISMIC PROTECTION IN BUILDINGS

 

A group of mathematicians have studied a new theory, which will help us to build an ‘invisibility cloak’ for buildings. It won’t make them light-invisible, but for something more unexpected: earthquakes.

Until some years ago, this concept was exclusive for science fiction, but each time, scientifics are achieving the goal to get invisibility in a wide range of context.

A team of The University of Manchester has focused on the invisibility theory to help protecting buildings and structures against vibrations and natural disasters.

They have demonstrated that protecting the key components of the structure with special pieces of pressured rubber, the buildings would become invisible for seismic moves produced by one earthquake. It would prevent serious damage to the building.

In 2009 an experiment was conducted and it demonstrated the viability of creating a deflector shield to protect buildings of earthquakes.

An earthquake generates two types of waves, superficial and deeply waves. This shield protects the superficial waves produced by the earthquake, which are more dangerous than those that go deep underground.

This technology would use concentric plastic rings which would be adjustable to the field to deviate the superficial waves.

By controlling the rigidity and the stability of the rings, we can assure that the waves which go through the shield entry smoothly in the material and compressed in little fluctuations of pressure and density.

This technology would be applied to the buildings by installing the rings in their foundations. This theory looks as a key to protect structures such as nuclear power stations, electric towers and governmental buildings from the damages of natural disaster and also from terrorist attacks, because it would provide invisibility in light, sound and vibration waves.

 

Thermal efficient box: description of my project

I would like to describe my group project (we have been working by 3) for my “Design of Energy-Efficient Building” class: building the most efficient box that is able to retain the highest amount of heat during a two hours experiment.

Goals

To understand deeply the environmental performance criteria within the build environment, it is important to care about the energy performance of a building. For this project, we have tried to build a box with an interior size of 3′ by 3′ by 4′ in which heat loss are minimal. The aim is to appreciate the purposes and benefits of energy modeling and to find the best solutions to design a box with the following conditions: an interesting price, and a nice aesthetic aspect, and which can retain the most heat energy during 2 hours, with a lightbulb of 150 watts on for the first hour. Before building the real box, we have made some simulations with the software IES-VE to find the best available materials to insulate it.

We intended to store energy inside the box at the same time as we avoid energy loss to the outside. To achieve this two goals, we have built a box with two layers of materials 1 and 2 with complementary properties. One of the materials must be an insulator to try to decrease heat loss. Since the duration of the experiment is two hours, the other material has to be able to store energy quickly and release once the heat power is off. To meet this objectives, the insulating materials envelop the whole box made of the other material.

Methodology

 1) Definition of the limits

The limits of the problem have been determined by the conditions in which we will test the efficiency of the box, the classroom: an inner size of 3′ by 3′ by 4′, a 150 W lightbulb heat source, an outside temperature around 72F, an experiment of 2 hours with one with the lightbulb on and the second one with the lightbulb off, a record of the temperature every 6 minutes, a turkey thermometer for measurements.

2) Research about materials

To choose efficient and relevant materials, we have been looking for the following criteria:

• the good thickness in mm

• the thermal conductivity in W/m.K

• the density in kg/m³

• the specific heat in J/kg.K

• the cost in $/m²

• and the grey energy in kWh/m³

 3) Research about wall assemblies

To choose efficient and relevant wall assemblies, we have been looking for the following criteria:

• the choice of different layers of materials

• the thermal resistance or R-value in m².K/W

• the thickness in m²

• the mass in kg/m³

• and the way to assemble the materials

4) Simulations

After deciding the different six wall assemblies, we have simulate them with IES-VE. Firstly, we have designed the geometry of the 3′ by 3′ by 4′ box. Then, in order to represent the classroom, the place of the experiment, we have created four buffer zones surrounding the box. After having integrated the physical features, it is possible to integrate the thermal conditions of the experiment.Finally, by drawing the inside temperature of the box in function of the time, we can compare the thermal degradation of the different wall assemblies and find the most performing one.

5) Construction of the model

After the simulations, we have decided to build a water and foam box. The construction materials we have chosen to build the “Water Tower Box” are:

• for the polyurethane boards layer, 3 foam insulating sheathings of 1/2 in. 4 ft. x 8 ft.

• and for the water layer, 936 bottles of water.

The goal will be to compare the results of the simulations and of the experiment.

Results

Here is the result of the construction of the box model:

 Here is the comparison between the experiment and the simulation with IES-VE:

Double-skin Facade

A building with a double-skin facade has an envelope consisting of two walls. The outer wall is usually out of glass, while the inner wall can be out of any building materials. Between each of the walls there is a cavity, usually varying from 5 to 50 inches. A larger cavity allows for installations such as HVAC, electrical and shading devices between the walls. [1]

So what is the point of having two exterior walls? In fact there are many good reasons, the best arguments for using a double-skin façade are increased U-value, pre-heating of ventilation air, better sound insulations, etc.

Double-skin façade on Mediaset’s Headquarters in Milan [2]

Usually the benefits of a double-skin façade are larger in cold climate countries. The cavity between the two walls will usually have a higher temperature then the outside temperature, and there are many ways to utilize that. However, if designed correctly you can benefit from double-skin facades in warmer climates as well. Especially through placing shading devices in the cavity. By placing blinds in the cavity, the solar waves are reflected before they enter the building. However, in warm climate the cavity may become very warm so good ventilation is required. Openings in top and bottom of the cavity ensures such ventilation.

The air cavity can be incorporated into the ventilation system in different ways. [3]

As well as reducing energy consumption, especially in cold climate, double-skin façades improve the sound insulation of a building. Double-skin façades are especially good for reducing low frequency sounds. A reduction between 15 and 30 dBA is normal [1]. A problem that could occur is noise traveling between rooms through the cavity. Sound absorbing materials in the cavity is therefore recommended. Another interesting benefit from double-skin façades are new architectural possibilities. Large glass areas are modern and popular among architects. Double-skin facades allows for such large areas without increasing the energy consumption.

Double-skin façades are by no means a new invention, and the first known building using this principle was finished in the early 1900’s. However, there has been an increasing interest for double-skin façades lately. One of the main reasons for the increased popularity is the applicability in reconstruction and renovation project. Double-skin facades can often be installed with minimal adjustments to the existing building.

Have a look at the following YouTube video for visualization of double-skin facades.

http://www.youtube.com/watch?v=FlGuK8he9SQ

[1] Ruyter, E. W. (2003) Double-skin façades. Online: http://home.online.no/~bar-he/pdf/diplom.pdf

[2] http://www2.dupont.com/SafetyGlass/en_US/whats_new/sentryglas_mediaset_facade.html

[3] Alibaba (2013) Curtain Walls. Online: http://www.alibaba.com/product-gs/389768855/Double_skinned_facade_curtain_wall_system.html

Comparison of different types of insulating materials

Depending on your construction conditions, which insulating material is more efficient for your building? It is now possible to introduce more environmental respecting materials such as cotton and wool insulation.

Cotton insulation

Because it can be harvested annually, cotton is considered as a rapidly renewable raw material, which has environmental advantages because of its long-cycle renewable resource extraction. However, it should be noted that current cotton growing practices are very pesticide intensive, this is one of the drawback of this material. Cotton insulation is made of around 75% from post-industrial cotton such as jeans, so it is not directly associated with those agricultural practices. At the end of its useful life, cotton insulation can, in theory, be recycled. Cotton insulation consists of 85% recycled cotton and 15% plastic fibers that have been treated with borate.

Cotton insulation in batts is easy to install and comparable to fiberglass about energy-efficiency. Nevertheless, we could underline the fact that it avoids some potential health problems of fiberglass. It does not itch when it contacts skin and contains no formaldehyde or other chemical irritants. Furthermore, it is a recycled material and it requires minimal energy to manufacture.

The thermal resistance of this product is R-3.4 for 1 inch thickness. Cotton insulation has thermal properties similar to those of fiberglass. However, this R-value is idealized, as effective insulation capabilities for all types of batts can be significantly lower due to typically deficient installation because of air leak. Plus, sealing air leaks as spray or blown-in insulation, further reducing actual energy performance of the building envelope. The cost of cotton batt insulation is about $1.20 per s.f.. Cotton insulation generally costs about twice as much as fiberglass batts.

 Wool insulation

Animal’s wool, such as sheep’s wool, used as an insulating material, is now available in batts form. The cost of sheep’s wool batt insulation is approximately $2.40 per s.f. Sheep’s wool is a natural product that is sustainable. The thermal resistance of it is R-3.5 for one inch thickness.

Mineral wool insulation refers to fiberglass, rock wool (made from basalt, a volcanic rock, and limestone) and slag wool (made from blast furnace slag). It is used in batts and board form in commercial buildings for fire-resistance and acoustical advantages. Mineral wool batts are made primarily of rock wool. Rock wool for residential insulation is more common in Europe, Canada, Oceania than in the United States of America. Mineral wool provides better acoustical absorption than fiberglass and has a higher insulating value of R-3.8 for 1 inch thickness. The price is around $ 0,7 per s.f..

Comparison between those insulating materials

MATERIAL	R-VALUE	COST $/s.f.
Cotton	3,4	1,2
Sheep’s wool	3,5	2,4
Mineral wool	3,8	0,7

The MSV Fire Alarm Problem

 

NOT ALL FIRE ALARMS ARE AS CUTE AS THIS ONE!

If you did not know this, but MSV in the last year has had frequent fire alarm problem. They have a record of about 20 days without an alarm going off. Last year they even had two go off in in one night. There are many different causes to these fire alarms including, hairdryers, people pulling it, microwaves, and some seem random. The goal of a fire alarm is to detect the unwanted presence of fire by monitoring environmental changes associated with combustion. Some of these reasons for the fire alarm are not included under that definition unfortunately the system in place in MSV is not the best. The system is old, faulty, and has not been maintained properly. Reasons for fire alarms for going on when there is no presence of fire is sometimes do to dust in the alarms or faulty wiring. I know they just put in new alarms in every room so that everyone can hear it, but that does not solve the original problem. The fact that the fire alarms are going off when there is not a fire. The reasons why this is a problem is not only the annoyance to the students living there, but the fact that the fire department comes every time it goes off. They are now charging the school every time it goes off thanks to its frequency. In result tuition is raised and everyone is annoyed.  There have been new advances in technology where the system actually checks to see if there is a fire before calling the fire department. This would be a welcome addition to MSV, however it is not economically sound choice at this time. It is however something to consider when a renovation is going to be done in the future, because eventually the charges to the fire department for their frequent visits will be greater than inserting a new system.

Introducing: Solar-Harvesting Pavement

Imagine if we could notably increase the generation of clean energy intake throughout all building surfaces and not just from their roof’s solar panels? Architects and Engineers continuo to place most of the building’s energy-generation equipment in rooftops, almost any newly designed rooftop functions as a miniature power plant turning sunlight into clean electricity, however with a growing ability to coat glass, paint and other surfaces with sun-harvesting technology now we can re-think and re-design the way we look at green solar energy intake in our buildings.

George Washington University in Ashburn, Virginia (US) is the first to put this new technology theory to test by installing the world’s first solar paneled pavement. Designed by Building Integrated Photovoltaics (BIPV) specialists Onyx Solar, the pavement panels are slip-resistant and semi-translucent for optimum aesthetic appeal and functionality. The energy generated by the pavement (approximately 400Wp) will power 450 LED pathway lights beneath the panels themselves.

In total 27 panels have been used in the pavement design which has been integrated into a popular Solar Walk between two of the university’s buildings, Innovation Hall and Exploration Hall. The Solar Walk was completed by Studio39 Landscape Architecture and Hubert Construction LLC in 2012 with design features suggested by current students of the university. The walkway also boasts a trellis with embedded solar panels which supply energy to Innovation Hall.

Eric Selbst, Senior Land Use Planner explains: “The Solar Walk is a great example of George Washington University’s commitment to sustainability and a reflection of the university’s forward thinking mentality. With an ever-increasing need for alternative energy solutions, it is critical to foster new trends such as this in building sustainable technologies. We are very excited about this project and proud to be a trailblazer in the development of new methods and sustainability.”

Aesthetics and solar energy.

When we talk about energy efficient and green buildings , One of the first things that comes to mind is solar panels and solar cells. For some home owners and business owners aesthetics is an insignificant trade off when it comes to reducing energy bills and carbon emissions. But for a substantial number of people the opposite is true.  So the question to my mind has always been how to consolidate energy savings with pleasing aesthetics and to this end i am always keeping a lookout for advances and means allowing the integration of energy efficiency and looking good. Some of the things I came across include the use of colored solar panels, as well as ideas to give unique aesthetic look while using conventional solar panels.

Colored solar panels

With the advancements in technology, Solar panels which were just previously available in black and blue shades are now being manufactured in red, emerald green, forest green, and polished marble. The colored variant of the solar panels are slightly less efficient, typically 1-3% less, a downside which is easily set off by the ability to use solar panels in situations where the older variants were not aesthetically viable.

 

 

Solar shingles and photovoltaic slates

Just like normal roof shingles, solar shingles are being introduced that blend in very nicely with the buildings architecture. These consists of a polycrystalline photovoltaic tempered glass module adhered to a metal shingle. 

Solar cladding

Architects use different types of cladding to create unique and beautiful facades. One of the ways with which we can not just create beauty but also fulfill or atleast cut down the energy useage of the buildings is the solar cladding.

Absorption Cooling

Absorption coolers use heat rather than electricity as their energy source. Because natural gas is the most common heat source for absorption cooling, it is also referred to as gas-fired cooling. Other potential heat sources include propane, solar-heated water, or geothermal-heated water. Although mainly used in industrial or commercial settings, absorption coolers are commercially available for large residential homes.

The absorption process is thermochemical in nature, as opposed to mechanical. Also, absorption chillers circulate water as the refrigerant instead of chlorofluorocarbons or hydro chlorofluorocarbons (CFCs or HCFCs, also known as Freon). The standard absorption chiller system uses water, as a refrigerant, and lithium bromide, as an absorbent, in its cycle. The lithium bromide has a high affinity for water. The process takes place in a vacuum, allowing the refrigerant (water) to boil at a lower temperature and pressure than it normally would, helping to transfer heat from one place to another. Small residential-sized units use ammonia as the refrigerant, and water as the absorbent.

 

HOW ABSORPTION COOLING WORKS

An absorption cooling cycle relies on three basic principles:

• When a liquid is heated it boils (vaporizes) and when a gas is cooled it condenses
• Lowering the pressure above a liquid reduces its boiling point
• Heat flows from warmer to cooler surfaces.

Absorption cooling relies on a thermochemical “compressor.” Two different fluids are used: a refrigerant and an absorbent. The fluids have high “affinity” for each other, which means one dissolves easily in the other. The refrigerant—usually water—can change phase easily between liquid and vapor and circulates through the system.

 

Heat from natural gas combustion or a waste-heat source drives the process. The high affinity of the refrigerant for the absorbent (usually lithium bromide or ammonia) causes the refrigerant to boil at a lower temperature and pressure than it normally would and transfers heat from one place to another.

In addition to being direct fired by natural gas, absorption chillers can run off of hot water, steam, or waste heat, making them an integral part of cogeneration systems or anywhere that waste heat in any form is available. Absorption chillers are generally used where noise and vibration levels are an issue, particularly in hospitals, schools, and office buildings. The primary advantage of absorption chillers is lower electricity costs. Costs can be even further decreased if natural gas is available at a low price or if we can utilize a source of low grade heat that is otherwise wasted in a plant. Comparing with electric chiller, absorption chiller has many advantages as above. However, it need more place to set the equipment. What is more, its efficiency is low.

Living Renewable Energy

 

A new facade system has been developed in Germany and it is literally green.  Algae filled panels cover all of the surface area not used by fenestration and doorways.  The system takes in nutrients and provides CO2 to the algae through a pipe system.  The algae can then be used to produce energy through their biomass.  There is a large heat output as a by-product which is very common among building systems, but here they found a use for the extra heat within another neighboring building.  Among the energy benefits, the facade also gets measurable acoustical noise reduction as well as a visible and dynamic green aesthetic.

The modular panels are filled with water and the algae flows into the tanks resulting in a bioreactor setup.  The algae flows between panels turning the facade green and resulting in heat and biomass.  For efficiency of the system, the engineers looked to how much of the sun’s radiation turns to energy through the biomass (which was around 48%).  Compared to PV and wind, the efficiency is lower but closer enough to conclude that it is a viable source of renewable energy for a building.  It also covers alot more square footage of the envelope since it is a wall aesthetic so beyond efficiency, a greater amount of energy could be produced from the greater surface area (whereas PV panels are usually limited to roofs).  People can now visibly see the impact that the environment has on the building and their impact on energy.  This psychological impact in the community is a definite plus.

http://www.bdcnetwork.com/video-arup-offers-tour-worlds-first-algae-powered-building

http://video.arup.com/?v=1_rbsfiiu7