SCADA vs EMS: 7 Essential Differences

At the start of an energy efficiency project, you’ll need to decide which system you want to put in place. You may have come across the terms SCADA and EMS.  For anyone not familiar with industrial and energy management systems you will need to understand the difference and work out which one is right for your project. In an earlier blog post we defined what SCADA and EMS are. In this article we will explain the differences between them, the key considerations for your energy project, and also how they can work together.

Let’s imagine this scenario. You work with an ESCO and have been put in charge of improving energy efficiency for a new client, a juice factory. They are struggling to stay competitive and need to reduce costs. You are challenged with reducing their energy costs by 30% in the first year. The client wants to know if they should install a SCADA or an EMS. What do you say?  

Refresher on the SCADA and EMS concepts

Supervisory control and data acquisition (SCADA) systems basically serve to control factory production. They began to be used in the 1970s as an evolution of industrial automation, allowing for the use of interconnected sensors and actuators, the status of which you can see from a control centre. An Energy Management System (EMS) monitors energy data and optimises energy use.

SCADA vs EMS: 7 Important Differences 


1. Hosting (on-premise vs. cloud)

A SCADA is an on-premise solution, meaning all control and data storage happens on a physical server. EMS is cloud-based, meaning all the data, programs and controls are stored and accessed over the Internet, from any computer.  

The benefits of a cloud-based EMS over on-premise are accessibility, flexibility and convenience. Being able to access and manage the system remotely from anywhere makes processes more efficient and gives you the power to respond quickly to incidents. Also, importantly for businesses with multiple plants or buildings, an EMS allows you to track and manage the energy data from all facilities from the same online platform, taking readings from the meter installed in each building. With a SCADA system you can only read the data from the site in which it is installed and the hardware connected to this local network. For a business with multiple factories, the cost of installing a SCADA in each factory would be very high.

The most common concern with cloud computing is the security and privacy of data, as having data on the Internet means it can be accessed by the service provider and could be vulnerable to hackers. But sometimes installing an on-premise system comes with a false sense of security – if a hacker can bypass the security of Google and Amazon’s servers, couldn’t they just as easily access your data on a physical server? Your data is only as secure as your security protocols, cloud-based or not. Therefore, it is crucial that you ensure your EMS provider has stringent security systems in place and a transparent privacy policy. Ownership and intellectual property of data is also a consideration you need to check when choosing a provider. (For more info, see 10 questions to ask your EMS provider).

One thing to bear in mind with cloud computing are the rules and regulations of the countries in which you are operating, and any restrictions on accessing or storing cloud-based data, especially sensitive information like government data. During March and April this year, China’s government closed down cloud storage in a digital content crackdown, and has drafted a Cybersecurity Law with specific provisions for data handling and storage.

To dive deeper into this topic, check out the post Cloud vs. On-Premise: Debunking SaaS Myths.

2. Set-up

The setup of a SCADA system requires complex installation on-site and a specialised consultant at the start of the project.

An EMS has a much simpler setup process. It involves an energy expert configuring the system with the data sources and the energy readings can be up on the platform in less than 48 hours.

3. Historical data

SCADA tracks data in real time, up to various readings per second. This means huge amounts of data, which cannot all be stored on the physical server. Therefore, you will get only recent data, rather than historical data going far back in time.

With an EMS you get readings less frequently (with DEXCell every 15 minutes). This allows the storage of much more historical data (unlimited, for all your sites), but still gives enough accuracy to be able to understand energy consumption trends and make smart decisions.

4. Hardware

A SCADA can only work with a limited number of hardware devices, normally those available from the SCADA factory. With an EMS you have more flexibility. EMS systems can be configured to work with an unlimited number of hardware devices, models and solutions (such as DEXCell which is hardware-neutral). If you only want to work with one hardware device for the foreseeable future then a SCADA is fine. However, if you want to be able to make the most of new developments that come to the market, an EMS will give you the option to pick and choose your hardware device according to your changing needs.

5. Energy analysis tools

With a SCADA you can see real time data but it does not have analysis tools. An EMS contains a suite of tools to help you analyse your energy data, track energy use over time across multiple factories, floors etc. With an EMS you can apply tariffs to convert energy to costs or CO2 emissions for advanced reporting. This helps you get an understanding of energy use to allow better energy decisions to be made. An EMS will benefit from ongoing development updates, however with a SCADA what you have is what you get. Any further customisation to add new features will incur a fee.

6. Use

SCADA are generally used to control industrial production processes, for example in manufacturing or infrastructure. It can be used to monitor and control processes e.g. temperatures, air pressure, production lines. EMS are used to track, analyse and understand energy consumption in factories, in order to take measures to improve energy efficiency.

7. Cost

On-premise systems require more installation, maintenance and support than cloud-based systems, therefore incur higher costs overall (starting from €100K per project). An EMS will require some initial costs, for instance hardware, and after that you will pay a monthly fee which varies according to your needs (see DEXCell pricing plans to give you an idea). With an EMS you are reducing by a factor of 10 the risk in your investment, as you don’t need to pay a high cost license upfront. The greater benefit of going under a SaaS model is that you only pay for what you use.  

How to integrate a SCADA with an EMS

Let’s go back to our scenario. You visit the headquarters of the juice factory, and find they already have a SCADA installed. The SCADA doesn’t give you enough data or analysis options to be able to confidently make energy decisions to meet the 30% energy savings target. Yet you want to make use of the system already in place and avoid doubling up on costs. What do you do?

Good news! Having a SCADA system in place means that during the installation process meters, sensors, probes will have already been installed. This means you already have access to an expensive piece of hardware which will be reading valuable data. So, you won’t need to buy any more hardware for your project, only integrate the SCADA with the new EMS.

The easiest way to integrate a SCADA with an EMS is to have the SCADA send data regularly via e-mail (with the file attached) or upload it to an FTP server. From then on, the EMS takes over and accesses the email or FTP to interpret and process the data and add it to the database. It might seem complicated at first, but at DEXMA we often do this for our clients and with our clever architecture the integration process takes less than 5 minutes. DEXCell Energy Manager already offers a list of compatible SCADAs and BMSs, including Siemens Desigo, Schneider StruxureWare, Trend and Wonderware (see the full list).  

The moral of the story

In short, if your client at the juice factory is interested in controlling the production process (production lines, temperatures, mass flows, machines etc), then an EMS will be no use, they will need a SCADA to be able to manage these complex processes. However, if the client has production under control and is only interested in energy – making energy savings – this is when you’ll need an EMS that can analyse energy data, detect inefficiencies, save energy, and verify these savings against targets. A SCADA doesn’t have these features.


The two systems provide the same function (automating processes using computer-aided systems) but for quite different uses. Yet, they can work happily together. In many projects that already have a SCADA, connecting with an EMS will provide a new level of functionality and intelligence for energy management. The SCADA is the “control master” that keeps things running smoothly, while the EMS is the “energy keeper” that talks to the SCADA, keeps tabs on energy and makes sure none escapes unnecessarily. 

Now that you know what these systems are all about, it’s time to decide which one is right for your energy efficiency challenge. If you want to get a clearer idea of what an EMS looks like in action, why not have a play around with the DEXCell Energy Manager. You can get access now (with no wait) to a free demo here.

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