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In 2008, the EU announced its triple goal related to energy efficiency under the ‘20-20-20 Policy’. With a wide range of far-reaching policies, the EU aims to cut its dependence on primary energy sources by 20%, reduce CO2 emissions by 20%, and also increase renewable energy production by 20% before 2020 To help lower electricity consumption by raising consumer awareness, all appliances released in the European market must display a label, which indicates the energy efficiency rating, annual energy consumption, and other energy-related information. In addition to helping consumers choose more efficient products, the labeling system encourages manufacturers to develop technologies, which require less energy to operate. Evolution of the TechnologyVRF systems are enhanced versions of ductless multi-split systems, permitting more indoor units to be connected to each outdoor unit and providing additional features such as simultaneous heating and cooling and heat recovery. VRF heat pump systems permit heating in all of the indoor units, or cooling of the all the units, not simultaneous heating and cooling. Heat recovery systems provide simultaneous heating and cooling as well as heat recovery to reduce energy use during the heating season. Over the past 15 years the technology has advanced in a number of areas: • Standard compressors to variable speed and capacity modulated scroll compressors • Direct driven outdoor fans to variable frequency drive, inverter-driven fans • Direct driven indoor coil motors to direct current or ECM-type motors • Variable capacity indoor units • Better heat exchanger surfaces with multi-segmented coils • Improved controls and diagnostics • R-22 to R-410A • Better refrigerant charge and oil management Advantages of VRF Some of the features of VRF systems should provide energy savings. These include: • Good part load performance due to multiple compressors and variable speed compressor systems permitting capacity modulation to serve 7% to 100% of the cooling or heating load. Many hours of HVAC system operation are spent between 30% and 70% of maximum capacity where the VRF system efficiency is high (Roth 2002). • Good zone control, saving by not conditioning unoccupied zones and by providing the capability to condition single zones off hours at a reasonable cost. Figure 3 shows how VRF systems can provide zone control, including simultaneous heating and cooling. Heat recovery is readily accomplished with the refrigerant when some of the indoor units are heating and some of the units are cooling. According to one manufacturer’s published data, if a 50% demand for full cooling and a 50% demand for full heating exist, in the heat recovery mode the compressor would only be 48% loaded. • Duct losses are confined to the ventilation air which is normally about 1/5th of the air flow of a ducted system circulating and conditioning both the ventilation air and the recirculated air. (Since ducts are often in unconditioned spaces, duct losses may not contribute to building space conditioning). • The refrigerant is used directly as both the working fluid and the heat transfer fluid tending to make the VRF system more efficient than systems that use air or water as a secondary heat transfer fluid for delivering heating or cooling. • The use of R-410Aand other features such a variable speed compressors, multiple speed fans and blowers, refrigerant circuitry, electronic expansion valves and advanced controls contributes to enhanced low-temperature performance • Better comfort. Since the system can be modulated to follow the load, units can remain running to maintain the temperature within narrow limits, assuring a comfortable temperature envelope. • Low noise levels. Levels are 24 dBA for the indoor unit and 56 dBA for the outdoor unit. • Flexible and quick installation. Only a small (3” or so) opening is needed for the refrigerant piping. • Low-profile, low space requirements and light weight make units easier to fit into tight spaces and to avoid obtrusive terminal units that could spoil the aesthetics of a space. • Modularity allows easy apportioning of energy costs among tenants or operations. Increased useful building space is enabled by reducing floor to floor height (12” ceiling void vs. 20”) and eliminating the need for a machine room. • Avoids the need for an on-site, trained operator as might be desirable with a large chiller based system

وظيفة وسائط التبريد في دوائر التبريد والتكييف وسائط التبريد هي المادة التي تستخدم كناقل للحرارة داخل دائرة التبريد, حيث تحدث عملية التبريد نتيجة التغيير الذي يحدث في خواص تلك المادة نتيجة تغييرات الضغط ودرجة الحرارة في دائرة التبريد فيقوم وسيط التبريد بطرد الحرارة من الدائرة عند المكثف لتتحول من الحالة الغازية الى الحالة السائلة عند ضغط ودرجة حرارة تعادل او اعلى بقليل من الوسط المحيط ..ثم بعد ذلك تقوم باامتصاص الحرارة داخل المبخر لتتحول من الحالة السائلة الى الحالة الغازية او البخارية مرة اخرى ولكن عند ضغط ودرجة حرارة منخفضة جدا وبذلك تحدث عملية التبريد والرسومات بالاسفل توضح مكونات دائرة التبريد وتمثيلها على منحنى الضغط والحجم -:في البداية نود ان نوضح نبذه مختصرة عن الانواع المختلفة لوسائط التبريد المستخدمة في انظمة التبريد وتكييف الهواء وبدائلها الحاليه وهي كالتالي  غاز النشادر (الامونيا) : وهو يعتبر اول غاز تم اكتشافه كوسيط تبريد في انظمة التبريد والتكييف الانضغاطية والامتصاصية الى ان اكتشفت شركة جنرال الكتريك بعد ذلك عائلة الفريونات  R 11 : يستخدم فريون (CF CL3) 11- مع ضواغط الطرد المركزى، نظراً لأنخفاض ضغطه الفعال ولكبر أزاحة الضاغط المطلوبة، ولتكييف هواء المصانع، المخازن والمسارح لأن درجة غليانه عند الضغط الجوى 23.7°م R 12 : يستخدم فريون (CF2 CL2) 12- كمائع تبريد مفضل لأمانه وخواصه الممتازة ومنها عدم إذابته للزيوت. درجة غليان فريون – 12 عند الضغط الجوى هى – 29.8°م لذا يستخدم فريون – 12 للحصول على درجات الحرارة المتوسطة فى الثلاجات المنزلية والتجارية R 22 : خواص فريون (CHF2 CL) 22- أحسن من خواص فريون – 12، درجة حرارة غليانه عند الضغط الجوى – 40.8°م وحجمه النوعى أقل من نظيره لفريون – 12 عند درجات الحرارة المنخفضة، لذا يستخدم فريون – 22 حالياً بدلا من فريون – 12 (للمبردات العميقة)، وللأغراض الصناعية ولمخازن التبريد للحصول على درجات حرارة منخفضة والفريون – R22 يذوب فى الزيت عند درجة حرارة التكثيف وينفصل عن الزيت عند درجة حرارة التبخير, ويفضل استخدام فريون – 22 بدلا من فريون – 12 لأن سعته التبريدية أكبر بنسبة 60% لنفس الضاغط وفيما يلي صورة توضح الاشكال الشائعه لاسطوانات الفريون المختلفة المستخدمة في عمليات التبريد وتكييف الهواء أكتشف عام 1974 وجود خفض فى نسبه غاز الأوزون الموجود بطبقه الاورون يسمح بنفاذ الأشعة فوق البنفسيجية. وتبين عام 1985 أن سبب الثقب أنبعاث موائع التبريد الكلوروفلوروكربون (CFC). وانتشارها لأعلى نحو طبقات الغلاف الجوى العليا ولاعتبارات بيئية تم توقيع بروتوكول مونتريال عام 1987 والذى ينص على خفض انتاج (CFC) وتوقفه عام 2000 بعد استحداث موائع بديلة غير مؤثرة على طبقة الأوزون وقد تم تأكيد توقيع بروتوكول مونتريال فى لندن عام 1990 وأتفق على تداول الموائع (CFC) فى الدول النامية حتى عام 2010 الى ان يتم التخلص منها نهائيا عام 2020   والصورة بالاسفل توضح نسبة تاثيرات غازات التبريد المختلفة على طبقة الاوزون والنتائج المتوقعه بعد اتفاقية مونتريال : وفيما يلي البدائل الشائعه لوسائط التبريد الجديدة وهي كالتالي R 134 A : يستخدم فريون 134A كبديل آمن لفريون R12 في الثلاجات المنزلية ومبردات المياة ومكيف السيارة ويعتبر صديق للبيئة نظرا لعدم تأثيره في طبقة الاوزون حيث انه لا يتفاعل مع الاوزون لعدم احتوائة على الكلور R 410 A  : وهو ما يهمنا في هذا الموضوع لانه الغاز المستخدم كبديل لغاز R22  وهو يستخدم في وحدات التكييف التي تعمل بنظام VRF  والتي لها قدرة عالية على توفير الطاقة في المباني الاعلى كفاءة تم اكتشاف R 410 A عام 1991 ثم تم تطويرة من قبل شركة Honeywell  ورمزة الكميائي CFC  (Hydroflurocarbon) وهو خليط من وسيط التبريد R32 مع وسيط تبريد R125  بنسبة 50%  الخصاص التي يتميز بها R410A  عن R22 يعمل بكفاءة اعلى حيث ان قدرته على امتصاص وطرد الحرارة اعلى من R22 . يساعد على تبريد اكثر للضواغط المستخدمة معه ويحد من خطر ارتفاع درجة حرارة الضواغط. يعمل بضغوط اعلى من R22 لذلك يتم استخدام ضواغط ذات متانه عاليه لتقليل الحد من فرص التكسير. يتم استخدام زيوت اكثر لزوجه مع الضواغط المستخدمة معه مما يجعله يعمل بشكل اكثر كفاءة. مع منع R22 من الاسواق ستكون اسعارة عالية بالمقارنة مع R410A    كفائته اعلى في توفير الطاقه المستهلكه وافضل بكثير للبيئة.  يساعد على اعطاء فترات ضمان اكبر للوحدات التي يستخدم بها لكفاته العالية في التشغيل وتفصيلاً، أفاد نائب الرئيس والمدير الإقليمي لدى جمعية المهندسين الأميركية (ASHRE)، الدكتور أحمد علاء الدين، بأن «الغازات المستخدمة في أجهزة التكييف، تستهلك طاقة كهربائية أكثر من الظروف التقليدية بنحو 30%، كونها غير مطابقة للمعايير البيئية والتي تتناسب مع الارتفاع في درجات الحرارة خلال الصيف  وكما نرى   R410A يحتوي على مزايا كبيرة جدا بالمقارنة بوسائط التبريد الاخرى ومما يتماشى مع التوجه العالمي لاستخدام اجهزة اعلى كفائة واقل استهلاكا للطاقة ومحافظة على البيئة

When it comes to selling variable refrigerant flow (VRF) technology, one of the first things contractors need to do is determine when and where the technology should be applied. After determining VRF is the best fit for a project, the key is to talk about efficiency up front. “It’s perhaps the most efficient air-cooled system. You also want to talk about ease of installation, a reduction in install time, and labor savings. We typically start the conversation with a discussion on how efficient these systems are and how much money they can save over the course of time on electric bills.” However, sometimes clients don’t leave contractors much of a choice when it comes to determining when to use certain equipment. “If the client is already convinced to go down the route of VRF or chillers, for example, we wouldn’t necessarily try to dissuade him from one course or the other unless we were clear the option he has chosen was not the right one for his building, “Customers rely on you to steer them in the right direction. As with any other profession, chances are great the consumer doesn’t know anything about the product or new technology unless you bring it up, most are not familiar with the technology, although it is becoming more popular. If you have the patience and take the time to explain what the technology has to offer, it makes the sell much, much easier. you must keep the old theory in mind that people buy from people they like. Many times, personality comes into play over technical knowledge.”Communicating Benefits From the consumer’s point of view, perhaps the most important benefit of VRF is its energy-efficiency savings potential. However, there are numerous advantages of which consumers may not be aware. “To start with, a VRF system does not put all the eggs in the same basket in the way a central chiller can,” Areas can be zoned; system distribution can be vertical through the building or horizontal, depending upon its orientation and usage; and the EER of properly designed and operated VRF systems are invariably better than a chiller system of the same capacity — particularly as far as low load performance is concerned. Plus, there is the ease of installation. There is little to go wrong as there are no pumps, dry air coolers/cooling towers, air handling units, etc., and, in the event of a unit failing, it can be taken out of circuit while repairs are carried out and the rest of the system can continue to function. If a large chiller fails, then the entire system, or a large part of it, is usually out of action.” Three major advantages, including energy efficiency, when selling VRF to clients. “Between the high SEER energy ratings and the possibility to spot-cool by turning off several areas when they’re not occupied, the monthly operation cost savings speak for themselves. Secondly, if it’s a high-occupancy area, what better application can address different peoples’ comfort levels than VRF One room could be 68F, while another space may be 78F, and, if we introduce heat recovery, we can offer simultaneous heating and cooling applications with certain brands.” VRF eliminates the need to employ separate controls contractors in commercial applications, said Ledsinger. “VRF is the closest to plug-and-play as possible,” he said. “With other commercial HVAC systems, you usually have to hire a separate controls contractor or separate controls provider, someone separate from the equipment provider. With VRF, the controls come with the equipment and, as long as you wire it in right, it all works, and you don’t need a separate controls contractor or provider. We use that one [selling point] a lot. The larger the job, the more money you save.” Addressing Cost Concerns VRF applications typically feature high initial costs, which may cause some clients to hesitate when considering the purchase. “Installation cost and time plus the efficiency, as described above, can easily overcome the higher initial cost. Plus, lower maintenance bills will be coming in the future. The best solution to overcoming cost concerns is for contractors to learn how to properly estimate a job. “In the past, before contractors were familiar with VRF, they would add a lot of fudge factor into their pricing because they didn’t know quite how to do it,” “Now that they’re familiar with it, we have contractors that can price it accordingly, and it’s very competitive with other commercial HVAC technologies. Usually, on an overall HVAC contract basis, VRF projects come in very competitively priced. “When VRF is compared to other technologies on an equipment basis, just equipment versus equipment, it’s usually going to come in higher because there are more components and they are a little bit more advanced electronically,” But, then you start factoring in labor savings, the savings on controls, and other savings. If you just look at equipment versus equipment, they may go into sticker shock, but the contract itself to put HVAC. in the building might be less for VRF. You must also take into account architectural savings because VRF takes up less space, structural savingsbecause VRF weighs less on the roof than most of its counterparts, and electrical installation savings because VRF indoor components don’t draw very much energy, so your panels can be smaller, disconnects and fuses are all smaller, and the wiring is smaller. All of that adds up to a lower upfront cost than most competitive technologies. Looking down the road, past initial costs, the energy savings are substantial.”

Variable refrigerant flow (VRF) systems, which were introduced in Japan more than 20 years ago, have become popular in many countries, yet they are relatively unknown in the United States. The technology has gradually expanded its market presence, reaching European markets in 1987, and steadily gaining market share throughout the world. In Japan, VRF systems are used in approximately 50% of medium-sized commercial buildings (up to 70,000 ft2 [6500 m2]) and one-third of large commercial buildings (more than 70,000 ft2 [6500 m2]) What is VRF? Many HVAC professionals are familiar with ductless mini-split products. A variation of this product, often referred to as a multi-split, includes multiple indoor evaporators connected to a single condensing unit. Ductless products are fundamentally different from ducted systems in that heat is transferred to or from the space directly by circulating refrigerant to evaporators located near or within the conditioned space. In contrast, conventional systems transfer heat from the space to the refrigerant by circulating air (inducted systems) or water (in chillers) throughout the building. VRF systems are larger capacity, more complex versions of the ductless multi-split systems, with the additional capability of connecting ducted-style fan coil units. They are inherently more sophisticated than multi splits, with multiple compressors, many evaporators, and complex oil and refrigerant management and control systems. They do not provide ventilation, so a separate ventilation system is necessary. The term variable refrigerant flow refers to the ability of the system to control the amount of refrigerant flowing to each of the evaporators, enabling the use of many evaporators of differing capacities and configurations, individualized comfort control, simultaneous heating and cooling in different zones, and heat recovery from one zone to another. This refrigerant flow control lies at the heart of VRF systems and is the major technical challenge as well as the source of many of the system’s advantages. VRF Benefits VRF systems have several key benefits, including: Installation Advantages. Chillers often require cranes for installation, but VRF systems are lightweight and modular. Each module can be transported easily and fits into a standard elevator. Multiples of these modules can be used to achieve cooling capacities of hundreds of tons. The relatively light weight of the system also may reduce requirements for structural reinforcement of roofs. Because ductwork is required only for the ventilation system, it can be smaller than the ducting in standard ducted systems, reducing building height and costs. In cases where operable windows are present and meet code requirements for ventilation, VRF systems are also particularly suitable for retrofitting historical buildings without disturbing the structure or for older buildings with no air conditioning. Design Flexibility. A single condensing unit can be connected to many indoor units of varying capacity (e.g., 0.5 to 4 tons [1.75 to 14 kW]) and configurations (e.g., ceiling recessed, wall-mounted, floor console). Current products enable up to 20 indoor units to be supplied by a single condensing unit. The modularity also makes it easy to adapt the HVAC system to expansion or reconfiguration of the space, which may require additional capacity or different terminal units. Maintenance and Commissioning.VRF systems with their standardized configurations and sophisticated electronic controls are aiming toward near plug-and-play commissioning. Because they are DX systems, maintenance costs for a VRF should be lower than for water-cooled chillers, so water treatment issues are avoided. Normal maintenance for a VRF, similar to that of any DX system, consists mainly of changing filters and cleaning coils. However, chillers, which often operate for 20 to 30 years, normally would be anticipated to have a longer life expectancy than a DX system such as a VRF.2 The large number of compressors in a VRF may create a higher probability of compressor failure, although the redundancy also leads, in many cases, to a greater ability to continue to occupy the space while repairs are made. • Comfort. Many zones are possible, each with individual setpoint control. Because VRF systems use variable speed compressors with wide capacity modulation capabilities, they can maintain precise temperature control, generally within ±1°F (±0.6°C), according to manufacturers’ literature. Energy Efficiency. The energy efficiency of VRF systems derives from several factors. The VRF essentially eliminates duct losses, which are often estimated to be between 10% to 20% of total airflow in a ducted system.3 VRF systems typically include two to three compressors, one of which is variable speed, in each condensing unit, enabling wide capacity modulation. This approach yields high part-load efficiency, which translates into high seasonal energy efficiency because HVAC systems typically spend most of their operating hours in the range of 40% to 80% of maximum capacity.  

What is the VRF system? Variable refrigerant flow (VRF) is an air-condition system configuration where there are one outdoor condensing unit and multiple indoor units. The term variable refrigerant flow refers to the ability of the system to control the amount of refrigerant flowing to the multiple evaporators (indoor units), enabling the use of many evaporators of differing capacities and configurations connected to a single condensing unit. The arrangement provides an individualized comfort control and simultaneous heating and cooling in different zones. With a higher efficiency and increased controllability, the VRF system can help achieve a sustainable design. The VRF technology uses an inverter-driven scroll compressor and permits up to 60 indoor units to operate from one outdoor unit (varies from manufacturer to manufacturer). The inverter scroll compressors are capable of changing the speed to follow the variations in the total cooling/heating load as determined by the suction gas pressure measured on the condensing unit. What is the difference between VRF system and the Multi-split system? VRF system is similar to the multi-split system which connects one outdoor unit to multiple evaporators (indoor units). However, multi-split systems turn OFF or ON completely in response to one master controller, whereas VRF systems continually adjust the flow of refrigerant to each indoor evaporator. The control is achieved by continually varying the flow of refrigerant through a pulse modulating valve (PMV) whose opening is determined by the microprocessor receiving information from the thermistor sensors in each indoor unit. The indoor units are linked by a control wire to the outdoor unit which response to the demand from the indoor units by varying its compressor speed to match the total cooling and/or heating requirements. What are the types of VRF system? There are two types of VRF system; Heat pump (two pipes) system & Heat recovery (three pipes) system. Heat pump (two pipes) system permit heating or cooling in all of the indoor units but not simultaneous heating and cooling. When the indoor units are in the cooling mode, they act as evaporators; when they are in the heating mode, they act as condensers. Heat Recovery (three pipes) system have the ability to simultaneously heat certain zones while cooling others; each manufacturer has its own proprietary design (2-pipe or 3-pipe system), but most use a three-pipe system (liquid line, a hot gas line and a suction line) and special valving arrangements. In this case, the heat extracted from zones requiring cooling is put to use in the zones requiring heating. This is made possible because the heating unit is functioning as a condenser, providing sub-cooled liquid back into the line that is being used for cooling. While the heat recovery system has a greater initial cost, it allows for better zoned thermal control of a building and overall greater efficiencies. What are the advantages of VRF system? Energy Efficiency. VRF system uses less energy for several reasons. The system is designed to provide exactly the amount of cooling needed for the current conditions, which means it runs less frequently and at a lower capacity. The VRF system is also designed to capture heat from the cooling process and reuse it in other zones that may need heating. Quiet Operation. In a VRF system, the noisier condensing unit is typically outside, and the indoor air handlers are smaller and quieter than a traditional split system. Heat And CoolSimultaneously.The VRF system captures residual heat absorbed from the air during the cooling process and redirects that heat to other parts of the building that need heat. Consistent Comfort.The VRF system’s compressor can detect the precise requirements of each zone, and send the precise amount of refrigerant needed to do the job. As a result, each area of your space is consistently comfortable with well-controlled humidity and no hot or cold spots. Less Downtime.Since the VRF system is designed to run only when needed and under partial load conditions, there is less wear and tear on the parts. That means fewer breakdowns. Also, if something goes wrong with one indoor unit, often the others are unaffected. That means your whole space won’t be without air conditioning all at once. Requires Less Space. VRF system doesn’t usually require ducts, they don’t require as much wall and ceiling space for the equipment. Modern Controls.For residences, you can take advantage of mobile control technology that lets you adjust temperature settings for each zone from your mobile device. For commercial settings, the VRF system’s built-in controls may allow you to skip purchasing expensive building management software. What are the issues to be considered when choosing the VRF system? Higher Up-Front Cost.VRF system may cost more than traditional central air systems up front. But this cost can be offset by lower energy bills and repair expenses over time. Limitation of Refrigerant Piping. Each manufacturer specifies both the size of the pipework required for their system and the maximum permissible vertical and total refrigerant pipework runs. Compliance with ANSI/ASHRAE Standard 15-2001. VRF system must comply with ASHRAE Standard 15-2011 – Safety Standard for Refrigeration Systems (ANSI approved). ASHRAE Standard 15-2001 guides designers on how to apply a refrigeration system in a safe manner and provides information on the type and amount of refrigerant allowed in an occupied space. Requires An Experienced Installer.These systems are extremely sophisticated and require a trained and experienced installer. If you choose a company that doesn’t understand the unique requirements of VRF system, you’ll end up with sub-par performance and you’ll pay more, in the end, to have an expert come in to fix it. “VRF system provides an alternative realistic choice to traditional central systems. It captures many of the features of chilled water systems while incorporating the simplicity of DX systems.”

What is the difference between contractor and solution provider?  What is the contractor definition? Independent entity that agrees to furnish certain number or quantity of goods, material, equipment, personnel, and/or services that meet or exceed stated requirements or specifications, at a mutually agreed upon price and within a specified timeframe to another independent entity. What is solution provider definition? An umbrella term for an organization that offers a combination of product, installation, and design. handles the project needs of their client from concept to installation. This process normally involves studying the client’s current infrastructure, evaluating the client’s needs, specifying the mix of manufacturers’ product and feasible design required to meet project goals. Vision: Solutions provider companies are generally the companies that can look after your project throughout its entire duration. They can help you understand your operating requirements and running cost and can then develop a design and construct the design accordingly. What is the role of energy efficiency solution provider? understand the logic behind the behavior of building industry and that is important for successful development and deployment of proper technologies. Providing benchmarks on sustainable buildings is an essential requirement for decision makers to take the correct call of action to encourage energy efficient buildings. Solutions aiming to improve the energy efficiency of buildings and construction activities should be disseminated widely, making use of existing or new technology transfer programs. Influencing market mechanisms and encouraging research and development projects. Access to top notch technologies: In many aspects, this is like comparing apples and oranges, as one company does the whole project, and the other just undertakes part of the project (contracting job). All the companies have access to the same materials, the same staff and operate within the same timelines, however, solution provider companies have an access to latest and top notch technologies and have a real partnership with reputed global technologies manufacturers. The difference really comes from understanding the bigger picture, strong relationships with technology manufacturers, high exposure to the top notch technologies, have experts of energy efficient solutions and ensuring that technical support during design, execution, and start-up. When to use solution provider? if you have the vision to achieve your energy efficient building and have solid plans for how your operating cost and energy bills will look,  you want to create a unique building that catches your business imaginary, cut you energy bills and works efficiently. solution provider has a real vision would definitely be your best option. they will undertake all of the planning and design that goes into – in other words a seamless turnkey solution. 365 Ecology is an integrated One Stop Shop engineering solutions house specialized in energy efficient cooling and heating solutions including and not limited Variable refrigerant flow Air Conditioning, Solar Water Heating, Heat pump, desert coolers and indirect evaporative cooling. Unlike most clean technology companies, we tend to focus on achieving energy savings via introducing a top notch technology of energy efficient systems.We offer a broad spectrum of services to make sure that your project is being effectively managed from start to finish and your energy needs are met. As we go into full force we start with evaluating your current energy consumption practices and needs in order to design a system that works best with your lifestyle in terms of being both energy-efficient and cost-effective while taking care of supplying and installing cutting-edge energy efficient technology.

365 Ecology is an integrated One Stop Shop engineering solutions house specialized in energy efficient cooling and heating solutions including and not limited Variable refrigerant flow Air Conditioning, Solar Water Heating, Heat pump, desert coolers and indirect evaporative cooling. Unlike most clean technology companies, we tend to focus on achieving energy savings via introducing a top notch technology of energy efficient systems.

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In large-volume spaces such as atria and covered malls, smoke management systems are often an important aspect of fire protection, with their primary goal being to ensure that  the impact of smoke and heat on occupants is not life threatening This involves keeping the height of the smoke layer above the highest level of occupancy for a defined period, longer than the expected time to evacuate the building. Smoke Control Vs Smoke Management Smoke control systems use fans to pressurize appropriate areas to limit smoke movement in a fire situation. Smoke management  systems include pressurization and all other methods that can be used singly or in combination to modify smoke movement. Smoke Management Approaches The following approaches can be used to manage smoke in atriums: Smoke filling:  This approach allows smoke to fill the atrium space while occupants evacuate the atrium. It applies only to spaces where the smoke filling time is sufficient for both decision making and evacuation. Nelson and Mowrer (2002), Chapter 4 of  Klote and Milke (2002), and Proulx (2002) have information on people movement during the evacuation. The filling time can be estimated either by zone fire models or by filling equation Unsteady clear height with upper layer exhaust: This approach exhausts smoke from the top of the atrium at a rate such that occupants have sufficient time for decision making and evacuation. It requires analysis of people movement and fire model analysis of smoke filling. Steady clear height with upper layer exhaust:  This approach exhausts smoke from the top of the atrium to achieve a steady clear height for a steady fire. our calculation method is presented here based on this approach.   Steady clear height with upper layer exhaust Definitions Atrium: A large-volume space created by a floor opening or series of floor openings connecting  two or more stories that is covered at the top of the series of openings and is used for purposes other than an enclosed stairway ; an elevator hoist way; an escalator    opening; or as a utility shaft used for plumbing, electrical, air-conditioning,  or communications facilities.     Clear height: Is the distance from the top of the fuel to the interface between the “clear” space and the smoke layer. Also called design height. Clear height   Design Fires: The design fire has a major effect on the atrium smoke management system. Fire size is expressed in terms of rate of heat release. Steady fires have a constant heat release rate. Steady design fire sizes for atriums ‐ Minimum fire for fuel‐restricted atrium              = 2000  kW ‐ Minimum fire for atrium with combustibles       = 5000   kW ‐ Large fires                                                                   = 25000 kW ASHRAE Handbook 2007 52 ‐ Table (2) Plume:   A column of smoke that rises above a fire Axisymmetric Plume: A plume that rises above a fire, does not come into contact with the wall or other obstacles, and is not disrupted or deflected by airflow. Smoke Layer: The accumulated thickness of smoke below a physical or thermal barrier.   Plugholing The condition where air from below the smoke layer is pulled through  the smoke layer into the smoke exhaust  due to a high exhaust  rate.  Makeup Air:  Makeup air has to be provided to ensure that the exhaust fans are able to move the design air quantities and to ensure that door opening force requirements are not exceeded. The large openings to the outside can consist of open doors, open windows, and open vents.   The large openings to the outside do not include cracks in the construction, gaps around closed doors, gaps around closed windows, and other small paths. It is recommended that make up air is designed at 85 percent to 95 percent of the exhaust not including the leakage through these small paths. The maximum value of 200 ft/min (1.02 m/sec) for makeup air is to prevent significant plume deflection and disruption of the smoke interface.           Calculations  Procedures: this calculation is based on steady fires and axisymmetric plume assumptions to calculate smoke exhaust flow rate from the top of the atrium to achieve a steady clear high. 1-Qc = ξ Q where : Qc: convective proration of the heat release rate (KW). ξ: convective fraction of heat  0.7 is often used. Q:   heat release rate (KW) based on the fire size. ASHRAE Handbook 2007 52 ‐ Equation (24)   Steady clear height with upper layer exhaust 2-       Z f = 0.166 Q c^(2/5)    NFPA92B ‐ [6.2.1.1a(1)] Zf is a mean flame height (m) 3a-   M’ = (0.071Qc ^1/3 * Z^5/3)+0.0018Qc  NFPA92B ‐ [6.2.1.1b(1)]                                                                use this equation when Z > Zf M’: Mass flow rate in plume at height z (kg/s) 3b-  M’ = 0.032Qc^3/5* Z  NFPA92B ‐ [6.2.1.1C(1)]                                                                 use this equation when Z > Zf M’: Mass flow rate in plume at height z (kg/s)                                           4- Tp= Ta + (Qc/ M’ Cp)  NFPA92B ‐ (6.2.5) Where Tp : Average temperature  at elevation z (°C) Ta: Ambient temperature (°C) Qc: Convective portion of heat release rate (kW) M: Mass flow rate of the plume at the elevation z (kg/s) Cp: Specific heat of plume  gases (1.0 kJ/kg.°C) 7-  Vmax =4.16 γd^(5/2) *((Ts-To)/To)^1/          NFPA92B ‐ (6.3.3a) Where Vmax = maximum volumetric flow rate without plug holing at Ts, m3/s γ = exhaust location factor, dimensionless value is 1 or 0.5 Di = Diameter of the exhaust inlet  Di = (2 a* b)/a+b   d = depth of smoke layer below lowest point of exhaust inlet, m Ts = absolute temperature of smoke layer, K     To = absolute ambient temperature, K     8- S min = 0.9 Ve ^1/2   NFPA92B ‐ (6.3.9a) Where Smin = minimum edge-to-edge separation between inlets, m Ve = volumetric flow rate of one exhaust inlet, m3/s 9-  M’ make up = 0.85 M’ exhaust   References NFPA 92B Guide for Smoke Management System In Malls,Atria, and Large Areas. ASHRAE APPLICATIONS 2007,