top of page
Anchor 1 - Issue 3

Webinar organised with the NPC of the Indian Government

Webinar startscreen NPC.png
Click to play
BAT Webinar direct drive ventilation NPC India compact
Simulation of
fan retrofit cost

In the previous newsletter of 22 March you read about the webinar for the Indian government. One of the Best Available Technologies (BAT) explained there was about the retrofit of ventilation systems: from belt driven to directly driven fans. In the PDF file next to this text you will find the slides that are explained here.

  1. There are many developments that still didn't penetrate into our daily ventilation technology. Therefore, we are wasting energy. Much electrical energy is used to move air and therefore it is important to have attention for the Energy Conservation Opportunities in this area. It is very probable that in your enterprise there is something to do here.

  2. A large hospital in Sweden with about 700 beds had a huge problem when the central ventilation broke down. This fan was very large and the only one. Therefore the problem was twofold: they had no backup ventilation. Moreover, the size of the fan didn’t allow to bring a new one into the Air Handling Unit (AHU) without breaking walls and ceilings. The solution was to cut the old fan in pieces and to bring a “blowing wall”, an array of 15 plug-in fans into the AHU. This didn’t save only energy but gave even more air, so much was the gain in efficiency. Moreover, the 15 fans where easily put into the AHU and gave enough redundancy to eliminate any worry about future problems with security of air supply.

  3. Let's compare in this slide the old and new technology. 

    • The AHU is reduced in size, so the space can be used for other energy-saving measures, for sample better filters or a larger heat exchanger. It also costs less because the designer has to work less. Mostly they need many hours in optimising the limited space or to fit in all the parts, apart from selecting them, so that they are compatible with each other.

    • The loss diagrams are very different. Firstly, the belt is missing in the diagram below. Secondly, the components in the mono bloc plug in fans are optimised to each other, so there is less loss of energy. 

    • The plug in fans have a direct drive motor.

    • The diagram with the Demand Controlled Ventilation (DCV) explains the fact that this approach is applicable in both the old and new configuration. It states that there must be a dynamic adaptation of the delivery of air in function of the real demand. This results in a very large energy saving, because the reduction of air speed will more than proportionally result in a reduction of fan power.

  4. The retrofit was in part explained in slide 2. The large fan is taken away and the side where the air is coming in (through the filters) will be filled with the fan array. The AHU will work now more on the principle of a pressure chamber instead of an acceleration room for the air. That means that the air may exit also from the side walls and not necessarily in line with the original fan. This gives more freedom in the design of the outgoing ventilation channels.
    In the hospital the retrofit was an urgency situation. In normal cases it is better to do a planned instead of a forced replacement. This means that the residual value of the existing plant will be discarded in favour of the additional savings of the new installation, when this is installed before the end of the lifetime of the old installation: the new technology will start earlier with saving and therefore create additional cash flow. This is the subject of the simulation in slide 6. 
    On this slide finally, there is an efficiency diagram, that shows that the optimal work point is even more efficient (68%) than the efficiency in the diagram on the previous slide (57%). That is because in reality, the working conditions will force the efficiency to wander over the efficiency curve, especially if also DCV is applied.

  5. The collateral benefits are those advantages, which can be added to the savings on the energy bill. I will always give attention to these benefits, which are usually neglected. That is a pity, because they might be more compelling to the decision-makers than the savings on the bill. With this technology they are the following:

    • ​More space in the machine room for other equipment (which might lead to additional savings or comfort);

    • Flexibility of design for the outgoing air channels: they can be connected on all walls of the AHU;

    • All the components, which in normal cases must be selected and fitted one by one, are already designed, optimised and included in the mono bloc. This gives the benefits that you see in the box on the bottom right. Note that among those, the energy saving is only one! Most of them are collateral benefits, that are seldom mentioned in retrofit projects. By the way, Demand Side Management (DSM) was described in the previous newsletter. Easy control of the plug-in fans through its electronic interface is a way to apply DSM also in ventilation and save additional money on the purchase of electrical energy. Here you see how important it is to think out of the box.

  6. ​As promised in slide 4, a financial simulation is presented of a retrofit while the old ventilation plant is still not at the end of its life. We see here that the net investment takes into account the difference between replacing with equal parts and with the modern technology. Moreover, it adds the residual value of the old installation, which could have functioned 3 year more, according to the nominal lifetime. In reality, one can just try to use it 30 year, maybe they tried just that in the Swedish hospital. So you have a net investment of 5000 monetary units, which you compare with the savings per year. You will note that these are nearly equal. 
    What happens next is the good practice of life time cost analysis. As you are talking about long times (20 years), you have to understand that cash in the future is less attractive than the same amount in the present (see the image with the birds). Therefore you discount the future cashflows with a percentage, each year. This doesn’t express only inflation but also the opportunity cost: you could have used the money elsewhere. In this way, you can express the total savings of nearly 50k in today’s money and you “loose” the stunning amount of 30k. But it is the reality. If you want, you can change the discount rate in the simulation, also given in the file here. You normalise every amount of money on the time line to the present, so that you can compare them in a fair way (compare apples with apples). And even then, comparing the discounted savings with the net investment (5 k, as we saw), you get four coins back for each coin you put into the project. In today’s discounted value. It is called the Savings to Investment Ratio or SIR. That is like a money machine. And this is a more serious presentation than the simple pay back time, which in this case. However, many Energy Conservation Opportunities don’t survive the judgment of the decision-maker. And if you add the collateral benefits to the SIR, the situation gets even better and you get them on your side in the most cases. 
    In the spreadsheet here next, you can try different economical scenarios with the spreadsheet that you see in this slide.

  7. In the conclusion you find my contact details and the Link Tree where you can click and arrive at my blogs, the vlog on YouTube and the various parts of the Birdseye Energy School.


​​During the discussion in the webinar there was a question about the ventilation in the Pharma industry and how decision-makers are reluctant to change the status quo. I proposed to subdivide the different areas in each Pharma production plant in 3 parts of cleanness. Where the product is actually mate and packaged, the cleanness is of extreme importance and I can imagine that they don’t want to change that without more assurance. However, there are also the production areas next to these superclean departments and in addition there are the storage areas, where the cleanness is even less important. Ventilation is present also in at least one of these two areas. I answered the question by suggesting to propose a ventilation retrofit project in these areas before talking about working on their very clean production area.

There was also a question about the possibility to save energy outside the scope of the fan retrofit in the AHU. I responded that a ventilation system is complex and can be optimised in many points. For example, there are plenty of additional possibilities in the AHU but also more on the peripheral side.

Anchor 2 - Issue 3

2. Dynamic tariffs

Dynamic energy tariffs - Irena.jpeg
Dynamic tariff simulation 1.png
Impressions from Dynamic Tariff simulation. Will be available.

it is interesting to know, for many enterprises, that they can have access to dynamic pricing of their electrical energy on several electricity markets, through specialised intermediate organisations. Instead of paying all the energy according to the usual 2 or 3 different price levels (like day and night tariff), fixed in time blocks for each 24 hours, they can have a dynamic price per kWh for each hour or even 15 minutes. This tariff will adapt to the real supply and demand situation on the market. That means: deep discounts during certain hours but also very expensive kWh’s during other hours. The mechanism is well explained at the website of an enterprise, which I used as an example during my lessons at an evening school in Switzerland. This explanation is in an old blog article of the cofounder, still valid because of its clear introduction: visit

I have (yet) no interests with this company but would like to cooperate with them, to be able to help my clients. That is because it is expanding in several countries in Europe, offering different options, not only for the consumers but also for producers of energy and owners of energy storage. You should explore these kind of market actors in your region. Where there is value, also market players will soon pop up.

It will be clear to you that the extremes in the dynamic tariffs can work against you, as much as it can help you. If your enterprise has flexibility to determine how much they consume in which hour, then it can have a good discount on the energy bill and will help the society to manage the volatility of supply and demand.

It will be very useful to have a cost-simulator, where the input is the consumption curve and the dynamic tariff. The outcome will be a cost at the end of the week, as this is the time unit that is repeated over and over again. More advanced simulators (and they can be spreadsheets) calculate also the cost for a whole year. I will attach in some future article such a spreadsheet. You understand, that if a week has a certain pattern on the short term, a year has an additional cycle on long term. Usually, these tariffs, even if influenced by a volatile market, will follow a known pattern, so that it is possible to predict with a certain precision the best time to increase or decrease your consumption. 

So, you will object: how will we be able to influence our consumption curve, if it is a function of, and thus commanded by the production or activity? 

The answer is: you can do this with an energy storage. We know however, that these are rather expensive. Battery storage costs about 200 USD per kWh of capacity, so with 4000 cycles in a lifetime, that is a cost of 0.05 USD per kWh of energy on top of its purchase. So that is the discount you want on the energy before break even is possible. Therefore you need the dynamic tariffs, because they go way beyond the difference of this order of magniture (0.05$), which is usually the difference between day and night tariffs of today’s price structure. Another possibility was described in the previous newsletter, about the ice storage (see the article about Demand Side Management (DSM)). If much of your consumption goes into a chiller, you can store the cold instead of the electricity. The price to store 1 kWh of transformed electricity will be much lower. You can now run the chiller at full power at tariffs that might be a fraction of the night tariff that you pay today. Also this can be simulated, I gave you in the last number a spreadsheet with costs of storage and tariffs for electricity.

As I will always mention the collateral benefits of technologies and approaches, here is what they are for the dynamic pricing, especially when used together with one or the other form of energy storage:

  • More peak power is available than before, because you may sum the capacity (in kW) of the electricity supplier to the capacity of your storage.

  • The electricity supplier will register “softer” peaks, so you will pay less demand charges, which are a component of the electricity bill that is less known. You pay it on the highest peak in the month, even if it occurred only 1 quarter hour in the whole month, so it is convenient to soften those peaks!

  • You can run your business in case of a black out, at least if the storage is large enough. If not, you can at least continue to run essential loads.

  • You are a very useful and modern market player, absorbing power that will otherwise find no buyer and avoid consuming when everyone else needs it badly. This function is really important in each kind of market. Why should you not be proud of it and communicate that openly?

In a following newsletter I will provide you with a spreadsheet with a simulator for dynamic pricing, so be sure not to miss one of them. I am always keen to give you concrete value for you enterprise. And for the Energy Transition.

Anchor 3 - Issue 3

3. When you are in a hurry, better keep it simple!

Click to play vlog

In my video blog at  I propose a middle level of Energy Manager. What is the sense of it? Like the title says, it is better to lower the hurdle if you want much participation. If Governments and international cooperative groups of these governments pin themselves to increasingly stringent ecologic objectives, it is not good to make the participation of large consumers to the Energy Transition complicated. There are now two extremes: from one side there is a tendency to fix the attention on certification of Energy Managers, from the other side it is really difficult to find them at all places where they belong. In certain cases it makes sense to focus on quantity and the quality will follow. This is my impression if I see what happened the last 3 decades, since for example Italy published its law on the “Responsabili per l’Energia” Law 10/91, art. 19, now exactly 30 years ago. In a very large hospital group in the UK I know a situation of a very qualified Energy Manager, which is alone and absolutely unable to tackle all Energy Conservation Opportunities. For this case, technical employees of for example Facility Management should be trained with a compact course and become his assistant. On the other side are the numerous medium enterprises, where they even don’t know what an Energy Manager is. For example in Switzerland, a few years ago, it was very difficult to find a job posting, where an Energy Manager was looked for. Is it better in other countries? For medium size energy consumers the same opportunity applies. Train a technical employee with a compact course and let her/him start with Energy Management and learn by doing. It is surely better than forgetting about the Energy Transition and the international commitments altogether. And of course, this Energy Manager must be given an adequate time budget, not assigning Energy Efficiency as a task for the Friday afternoon. That is the reason that I propose the Practical and Compact course on Energy Management, about which the following article tells more.

4. Practical and Compact course on Energy Management with inspiration

Anchor 4 - Issue 3
Wanted energy manager wide.jpg

Helvetica Light is an easy to read font, with tall and narrow letters, that works well on almost every site.

energy transparency - rohan-makhecha-jw3
Heading 6
bottom of page