In order to cope with Data Centers' hunger for energy, ever more efficient servers and other IT components are being developed. Data Center infrastructure such as cooling, power supply and distribution are also becoming increasingly efficient. In the field of air conditioning technology - one of the biggest energy consumers in a Data Center beside the servers themselves - considerable strides have been taken regarding efficiency in recent years. Today Free Cooling, either Direct or Indirect, is now commonplace in large Data Centers.

An air conditioning unit in a Data Center also takes in air at a certain temperature. Inside the air conditioning unit, this air is cooled and the extracted heat conveyed to the outside. So the air that exits the air conditioning unit is approximately 10 °C to 15 °C cooler.

That all works out fine then, doesn't it? Unfortunately not.

The above-mentioned 10 °C to 15 °C is the so-called air-side temperature difference, or Delta T.

In a theoretical ideal scenario – a closed circulation of air between the server and the air conditioning unit – there would be a certain air-side temperature difference, and the air conditioning unit would work at its planned maximum level of efficiency.

In a real Data Center, this is sadly not the case. The cold air exits the air conditioning unit, flows through the raised floor, enters the cold aisles through the perforations in the raised floor grilles, is sucked in by the server, heated, blown out into the hot aisle, and then begins its journey back to the air conditioning unit. However, air is stupid and lazy. It doesn't know that this is the route it has to take, and showing it the way with blue and red arrows is no help at all.

Some of the air finds openings in the raised floor, e.g. cable cut-outs in the hot aisle that have not been sealed, gaps between the raised floor grilles or even grilles missing altogether below the racks. It then takes one of these shortcuts back to the hot aisle and straight back to the air conditioning unit, without ever having seen a server from the inside or having taken any of its heat away with it. Other bits of air take the planned route into the cold aisle, but then sneak between the servers through unused rack surfaces, or to either side of the servers, hot-footing it straight to the hot aisle and back to the air conditioning unit. This air does absorb a little heat, which the servers radiate to the outside.

Air that takes in only very little heat on its trip through the Data Center lowers the air-side temperature difference and therefore the efficiency of the entire air conditioning system.

Here's an example:

With an airflow of 45,000 m³/h and a Delta T of 15 °C (return air 35 °C, supply air 20 °C), an ASD 2010 CWU air conditioner from STULZ manages a capacity of 228 kW for a power consumption of 6.2 kW. The result is an energy efficiency ratio (EER) of 36.8.

Now, if the actual Delta T is only 10 °C (i.e. return air is only 30 °C) with the same airflow, power consumption and water temperature, capacity drops to 155 kW and the EER is cut to 25.0. As a result, the air conditioning unit has an efficiency 32 % below its possible or planned level.

At last, on October 29, 2015 it was time. During a large evening gala event in the Steigenberger "Drei Mohren" hotel in Augsburg, Germany, Readers' Choice winners received Silver, Gold, and Platinum awards in the various portal categories. Thanks to the fantastic support of DataCenter-Insider readers and STULZ partners, STULZ Sales Manager Mirko Hoffmann had the honor of receiving first place in the Cooling Systems category: the DataCenter-Insider Readers' Choice Award in Platinum. The STULZ team wishes to thank all those involved, in particular its extremely active STULZ partners, the readers of the DataCenter-Insider portal and its editorial team.

With a double-walled design, integrated inspection window and other equipment features, the STULZ CyberLab Series meets the requirements of VDI 6022 (hygiene inspections for air-handling systems).

Hamburg,14.10.2015 – STULZ introduces CyberLab, an air conditioning solution for test facilities, laboratories and museum archives. These compact air conditioners provide cooling capacity of 21 kW and have been specially designed for technical applications with demanding requirements for stable room-air conditions. STULZ CyberLab's cutting-edge control technology provides room-temperature control accuracy to within 0.5 K and a relative humidity fluctuation range of no more than 3%. These are precisely the kind of requirements in test rooms, where highly sensitive measurements are taken for quality assurance or standardization and where the need to comply with measuring accuracy means that stringent temperature and humidity limits are prescribed. The same applies to laboratory applications: whether biochemistry, pharmacy, lasers, optics or electronics – a stable air temperature and humidity level are some of the most important minimum requirements in the business. A low heat load is another factor common to most technical special applications. To provide energy-saving operation and precision cooling-capacity control of 0–100% in these conditions, STULZ CyberLab air conditioners are fitted with a refrigerant heater and a continuous-control electric heater. They also have an advanced, steplessly controlled EC compressor and outstanding partial-load efficiency, rendering them not only highly efficient but also robust enough for continuous operation. CyberLab units are supplemented with STULZ UltraSonic air humidifier units and a variety of filter options. With a double-walled design, integrated inspection window and other equipment features, the STULZ CyberLab Series also meets the requirements of VDI 6022 (hygiene inspections for air-handling systems).

The term "Free Cooling" suggests that you don't have to pay for this type of cooling. That is a fallacy. Is anything free these days? Below I will describe the Free Cooling solutions in use today.

Free Cooling

Free Cooling means that the power consumption of the air conditioning system at the site is reduced to the necessary minimum by suitable means, without compromising on reliability and availability. The words "suitable means" and "at the site" open up a very broad range of possibilities.

Direct Free Cooling

To put it briefly, this could be described as follows: window open, blow cold air from outside through the Data Center, pick up the warm air, transport it back outside, voilà! And physically speaking, that's exactly what happens. Only the process of "moving the air" requires energy.

Unfortunately, in real life things are not that simple. Outdoor air is not always in a condition that the IT equipment is comfortable with. Sometimes it's hot and sometimes cold, sometimes it’s very humid and sometimes very dry. What's more, outdoor air is not always clean. The outdoor air is often full of particles which can be very hostile to modern IT equipment.

To remove the heat load from the Data Center, a certain airflow is required, the amount of which depends on the air-side temperature difference. This airflow is supplied by the closed-circuit air conditioning units.

A certain level of so-called "redundancy" of air conditioning units is created, depending on the size and desired reliability level, to ensure reliable Data Center air conditioning. In other words, more units are installed (standby units) than are actually required for air conditioning. Normally, these units are only brought (automatically) into operation if a running unit switches off due to a fault (passive redundancy).

The latest closed-circuit air conditioning units make use of EC fans for ventilation. These fans are considerably more energy efficient than the older versions with AC motor. Another major advantage of these fans is that as the fan speed decreases, the motor's power consumption does not decline in a linear fashion as a function of the speed, but by the power of three.

The immediate questions that probably spring to mind are what this is all about, what it might mean for your business and whether these figures are good or bad. Those are the questions I'll be answering in this article, but first I would like you to know up front that we are all part of the reason that the Code of Conduct for Data Centres exists at all. In early 2007 for the first time I held a smartphone in my hands; a colleague in the USA had one already. My words at the time are still ringing in my ears: "I don't think I need this." No doubt you can picture how the story ends and why we all "have a stake" in the large number of Data Centers which now exist all over the world.

The "Noughties" was the decade when new media and mobile telephony took an outright foothold in private life, and now we can't imagine it without them. This boom resulted in Data Centers being built very quickly, and operational efficiency was not always a consideration. Winter or summer, Data Centers need air conditioning around the clock. The flipside to this is that badly planned Data Centers consume a lot of energy and therefore have high CO2 emissions. This is not a good thing. Moreover, it's avoidable. At the time, there were Data Center operators and manufacturers already capable of producing efficient solutions. Given that this was the case, it would have benefited a great many people had someone gathered them around a table and established this as a subject area. The European Commission's Joint Research Commission has recognized this and defined a voluntary code of conduct for data center efficiency.

Can a voluntary code like the Code of Conduct for Data Centres change anything at all?

As far as I'm concerned the answer is a resounding Yes! The code is aimed at Data Center operators, experts, consultants and businesses as well as manufacturers, all of whom are a necessary source of the many and diverse products and services required to build a Data Center. The intent behind the code is that all the businesses involved should pay greater attention to reducing Data Center energy consumption and explore the options for designing or adapting new and existing centers for better efficiency. So those responsible for the code of conduct have developed a variety of measures and guidelines which are available to everyone. Best practice guidelines have also been defined and an award launched to highlight the most exemplary solutions. As a manufacturer of efficient climate systems for data centers, we are involved in the initiative. We're especially pleased that two of the data centers singled out by the latest awards have a STULZ solution that uses Indirect Free Cooling. This also singles us out as a company in terms of our activities and the many years we've spent investing in developing and building efficient cooling solutions.

The success of the code is also based precisely on the fact that it is voluntary rather than being handed down from on high, and will continue to develop going forward. Furthermore, regular meetings mean that participants and endorsers can proactively join the initiative and bring their ideas and practices to the table.

How was the code developed?

105 participants and 228 endorsers – a very positive level of engagement given that we are talking about a highly specialized industry. While the initiative was founded by the European Union, lots of multinationals have joined. Participants include IBM, Telecity Group, ebay, British Telecom, France Télécom, Microsoft, Level 3, Unilever and many others, with over 250 data centers now involved. In short, this represents a huge amount of Data Center space and means that a great deal of energy has already been saved. For the most part, the endorsers and associations taking part are also multinationals, which is generating positive synergies in the field. The whole initiative is having a major influence and supporting businesses that have signed up to fly the flag for sustainability and environmental responsibility.

If you'd like to join us, we'll be happy to tell you how.

Joint Research Centre Institute for Energy and Transport (IET): iet.jrc.ec.europa.eu/energyefficiency/ict-codes-conduct/data-centres-energy-efficiency

2014 Awards European Code of Conduct for Data Centres iet.jrc.ec.europa.eu/energyefficiency/2014-awards-european-code-conduct-data-centre

For example, museums and archive rooms are used for storing unique and priceless cultural objects for very long periods. Here, historic books, documents, parchments, works of art, and artifacts or films are stored under clearly defined room conditions to protect them in the long term and to preserve them for future generations. In addition to air quality, light, and the danger posed by pests, the air temperature and the air humidity are the main factors that influence the durability of the materials. High temperatures speed up the reaction of harmful substances with the materials, alter the acid content, and promote microbiological growth. Temperature fluctuations cause expansion and shrinkage, which in turn leads to material fracture. A high level of air humidity leads to corrosion, warping, cracks, and bacterial growth, whereas low humidity causes the material to dry out and shrink.

In test rooms, in which all kinds of measurements are performed on a wide range of objects and materials using highly sensitive apparatus, it is also necessary to adhere to defined temperature and humidity conditions for the purpose of measuring accuracy. The periods of time that apply in this case are relatively short and are measured in hours or days. A measurement normally consists of a stabilization phase, in which the required room conditions are set, and the subsequent measurement phase, in which the actual measurement takes place. Major fluctuations in temperature or humidity influence the measurement process, reduce the precision of the measurement, and must therefore be reduced to a minimum.

Laboratories are used in a wide range of areas. A distinction is drawn between biology, chemistry, and physics laboratories. The processes that take place there are so diversified that it is impossible to list them all in this text. To provide just a small selection, for example, there are laboratories for biochemistry, botany, pharmacy, organic and inorganic synthesis and analysis, lasers, optics, electronics, and much more besides.

Once again, all of these applications require a stable air temperature and stable air humidity. Further important factors include the air quality, movement, distribution, and speed, as well as the noise level and static underpressure or overpressure.

All these applications therefore share the need for constant air temperature and humidity conditions at a thermal load that is either zero or only very low. The air conditioning that is to be used must therefore be able to meet these requirements in a very reliable (and also efficient) manner in the long term using suitable components and control algorithms. In the case of precision air-conditioning units that were developed for data center air-conditioning, this is only possible if these units are adapted accordingly. The CyberLab from STULZ was specially developed for these requirements and precisely controls the temperature and the humidity with a tolerance of +/-0.5°C and +/-3% relative humidity. This makes CyberLab the first choice for applications with these special requirements.

We pay careful attention to what our customers say, and monitor the market closely

STULZ GmbH began internationalizing in 1956 when it established its first subsidiary in the Netherlands. But it was not until we entered the Data Center air conditioning market that we needed to expand globally. Following the maxim “Think global, act local”, we established ourselves in the countries where our customers are. Today we have 6 international production sites, 16 subsidiaries and over 140 partners worldwide. Our growth has allowed us to build close relationships with customers and to implement a large number of projects tailored to local markets. We know from experience that every project has particular features to take into account. Usually this means adapting the product, but thanks to our extensive range of options, we have that covered. However, we are increasingly developing special, targeted, market-specific solutions in partnership with customers.

Lots of solutions doesn't necessarily mean flexibility

Nowadays there is a host of different, flexibly constructed solutions on the market which appear suitable for Data Center air-conditioning. This creates the impression that customers can easily find the right solution. However, take a closer look and you will see things differently: many of those products are mass-produced, or spin-offs of other cooling solutions which are not specified for Data Center air-conditioning and yet are still used for the purpose. But the products concerned are neither customized nor open to adaptation. STULZ's air-conditioning range offers extensive product depth, different product variants and differentiating features. It is our basic premise that the climate systems we make should provide maximum efficiency in every product group and size. For example, room cooling, high-density cooling, chillers, modular Data Center cooling and air-handling units from STULZ are available with optional Indirect Free Cooling. Room cooling, air-handling units and modular Data Center cooling are also available with Direct Free Cooling.

Customization – a major trend

These days, customers can choose from a wide selection of different cooling systems, performance variables and manufacturers. So Data Center operators can find themselves confronted by an overwhelming array of potential solutions, all of which must be evaluated. Because with air-conditioning in particular, there is a high risk of choosing a solution that may well be sufficient for the Data Center's planned usage profile, but turns out to no longer be a 100% match over time. The payback is not just unnecessarily high energy costs, but also a lack of flexibility during future expansion, or even shortcomings in operational reliability.

We know that many operators face technical and planning challenges when expanding their Data Center, as they have to take account of complex parameters such as local climate, spatial and room considerations, environmental and noise protection, not to mention safety requirements. To help meet these, STULZ offers customized, modular system solutions which can be adapted to suit virtually every project requirement and expansion phase. Even if the interiors of Data Centers and server rooms all over the world are scarcely distinguishable from one another, the requirements for Data Center air-conditioning are becoming increasingly individual. As a customer, you need to be able to trust your business to a company that can deliver the right product for your project.

STULZ CLIMATE.CUSTOMIZED. offers you the reliability of a global player combined with the flexibility of a family-run business. With over 40 years of Data Center air-conditioning experience behind us, you can count on STULZ.

1. Data Center location (annual temperature profile)
2. Data Center size
3. Planning a new Data Center or optimizing an existing one
4. Number of CW units (redundancy) and total airflow
5. Type of control
6. Data heat load
7. Possible water temperature level of external chilled water supply
8. Desired air-side temperature level in the Data Center (e.g. air temperature at the server inlet, return air temperature, supply air temperature, temperature difference between return air and supply air)

The last two points, in combination with the airflow, have an influence on the cooling capacity of the closed-circuit air conditioning units. It is therefore important to know and define these figures precisely right from the start.

The water temperature level of the external chilled water supply depends on the chillers used or the type of chilled water supply system. Modern, energy efficient chillers are capable of working with comparatively high water temperatures (20 °C inlet temperature, sometimes even higher). Older systems, on the other hand, are mostly unable to cope with these water temperatures. In some cities, a central district cooling system is in operation, which generally works with very high water-side temperature differences.

The next step is then linking this potential water temperature with the desired air temperature in the data center and the required cooling capacity for each unit.

The cooling capacity of an air/water heat exchanger, as used in CW units, is dependent on the internal design and size of the heat exchanger, and on the temperature difference between the air inlet temperature and the mean water temperature (possible glycol content is not taken into consideration here).

Therefore, the largest possible choice of heat exchangers is vital for planners and customers in the planning phase, so that they can find their optimum operating point.

For this reason, all CW units from STULZ's CyberAir 3 PRO series can be designed and ordered as standard with three different heat exchangers, which can be employed as requirements dictate.

Thanks to this choice of three heat exchangers, energy efficient operation for virtually any requirements is guaranteed, always and at all times. If very special conditions mean that optimum energy efficiency cannot be achieved with one of these three heat exchangers, however, individual or project-specific heat exchangers can be used.

A press release from "MarketsandMarkets" states that the modular Data Center market is expected to reach $40.41 billion by 2018 at a CAGR (compound annual growth rate) of 37.41% between 2013 and 2018. (1)

Due to this trend, numerous different products and solutions are entering the market. Many people are talking about containerized Data Centers when thinking modular. But the market and manufacturers make an important distinction between the different types of modular builds.

Free Cooling instead of compressor

Chilled water for efficient hotspot cooling

Direct Free Cooling

A living IT landscape

New buildings without compromise

Spot-on cooling with water

Where high-powered computers produce hotspots, chilled water goes to the heart of the problem and dissipates the heat. Liquid cooled server racks work especially efficiently in these cases. All liquid-bearing parts are strictly separated from the electronics.

Cool air guided with precision

Hamburg, Germany, 10.06.2015 – With its CyberHandler precision air conditioning system, STULZ presents a ready-to-connect air handling system for medium to large Data Centers. The development of the new series was based on the latest requirements in Data Center air conditioning. When producing the STULZ CyberHandler systems, both the supply air temperature window of the ASHRAE TC 9.9 Thermal Guidelines and the efficiency requirements of the ASHRAE 90.1 were taken into account right from the design stage. The system is designed to exploit the potential for savings, achievable by direct Free Cooling and adiabatics, while maintaining maximum integrated reliability. If required, the entire cooling process in the STULZ CyberHandler systems is ensured via compressors, so that the full nominal output is available even without using Free Cooling and adiabatics. The air handling systems are available in a range of output ratings from 55 to 460 kW and create a maximum airflow rate of 20,000 to 71,000 m³/h. The anti- corrosion outdoor housing can be easily installed next to a building or on a roof. The CyberHandler system is connected to the Data Center on the air side. The system gives Data Center operators more floor space for server or storage applications and can also increase operational reliability. Furthermore, there is now no longer any need to access the Data Center to service the air conditioning systems.

Data center infrastructure management (DCIM) has, quite simply, been a buzzword in the IT/data center business for years now. And yet ignorance often prevails regarding what DCIM actually is, and what its purpose is. 

Be chilled, not chilly!

Traffic jams in the air flow

Hotspots

Hamburg, 30.05.2015 – With the CyberCon series, STULZ is introducing a flexible outdoor air conditioning solution for Data Centers in a container format. These precision air conditioning systems are available as DX or CW versions and are delivered pre-installed in standardized 20-foot ISO containers. For the air conditioning of 40-foot Data Centers, two STULZ CyberCon containers can be combined as an end-to-end installation. The systems, which have a vertical air outlet, are specially designed for container Data Centers, and can simply be mounted on a container module with the server equipment that needs cooling. All connections take place on the air side only. The standardized all-in-one design of the CyberCon series meets all the requirements of mobile Data Centers. As server capacities grow, thanks to the STULZ E2 control system further air conditioning containers can easily be added and integrated in the building services management system (Modbus, BacNet). This enables even complex redundancy strategies – for multi-tier Data Centers, for example – to be achieved without problem. What's more, all models are available as dual fluid versions with two independent refrigeration systems, based either on the direct evaporator DX/DX system, the liquid cooled CW/CW System, or the DX/CW system. With two independent cooling sides, redundancy is already integrated in the unit.  

Data centres run 365 days a year. Their tightly packed server racks generate ever increasing computing power in an ever decreasing area – power that is almost entirely converted into heat. Climate control ensures reliable operation. It conveys heat outside right away. But then, the air conditioning in data centres devours a huge amount of electricity. In the worst cases, it uses more than half of the energy supplied to the data centre.

 
Energy efficiency in optimising, building and operating

Whether you are building a new data centre or optimising or running an existing one – choose energy-efficient air conditioning from STULZ. With expert advice, intelligent products and lasting service, we will be there for you throughout the life of your air-conditioning system.

Save electricity, increase performance

Gain room for manoeuvre in the management of your operating costs. Our energy-efficient precision air-conditioning systems cut the power consumption of your data centre by up to 40 %. Save on electricity bills. Or invest

Hamburg, 01.03.2015 – On February 4, air conditioning specialist STULZ was awarded the quality seal "Hamburg's Best Employers 2015". The family-owned company won this accolade thanks to its high level of staff satisfaction and its motivating work atmosphere. This time the prize-giving ceremony, now in its seventh year, was held in the Albert-Schäfer-Saal conference room at the Hamburg Chamber of Commerce. The award was handed to Ms. Jana Seifert, HR Manager at STULZ, and Personnel Officer Ms. Christiane Claus.