Choosing the right sized CHP unit for your business ensures optimal efficiency and good return-on-investment in the long run. As a more environmentally friendly and sustainable solution, you’re likely moving down this route in a bid to reduce emissions and lower bills. And the design and suitability of your system to the building in question is vital when it comes to achieving these two goals. In this guide, we’ll provide information to help you better understand CHP unit sizing and how to select the one best suited to your needs.

Why does size matter with CHP units?

Similar to that of standard boilers, having CHP units that aren’t appropriately sized for your building could cost you more in the long run. On the flip side, it could reduce efficiency and be the reason you don’t reach the emission reduction rates you originally forecasted. Smaller units will have to work harder than their capacity, reducing the potential for savings on your side. Larger units will sit idle or continuously startup, even when there is no demand. Minimum load thresholds are assigned to these units with the understanding that meeting them holds the greatest benefits for the business. Therefore, your unit needs to run for as long as possible every single day for you to get the ROI expected.

Equally, size contributes to the price. The cost of labour, installation, shipping, delivery and much more are impacted by the size of a system. Costs can reach upwards of £1500 per kWh and, therefore, efforts should be made to reduce these by choosing a unit suited to the location.

Consider demand

CHP units require a significant investment. While beneficial schemes such as the Climate Agreement can help to reduce environmental taxes, businesses need to establish whether the initial investment is worth it in the long run. To do this, they must consider demand.

CHP units should work to provide the baseline output required to keep your business moving. Additional power will be supplemented from grid-based electricity or excessive boiler heat. You want to avoid having a system that overproduces heat waste. Without the demand in place, you reduce efficiency and avoid the larger savings that could have been made.

Consider tracking

Are there times where demand for your power system significantly reduces? Demand that rises and falls can impact the efficiency of a CHP unit if proper measures aren’t in place. Units that allow you to modulate and adjust output in accordance will work alongside the size implication to ensure as much wasted heat is utilised appropriately.

Consider export options

If excess and unwanted heat energy is produced, do you have another use for it? Some businesses can feed this back onto the power grid. However, this can have an impact on electricity value.

Consider multiples

Many businesses can run efficiently with one CHP unit. However, fluctuating demand may mean that multiple units are a more effective solution. These can be utilised intermittently, as-and-when they’re needed, with the ability to partner them up during periods of high demands.

Other things to consider

Alongside the points above, you’ll want to think about:

  • How many hours the demand for multiple energy sources (including those from boilers and CHP units) is required per year.
  • Spark spread – the difference between wholesale electricity and the cost of production.
  • Whether the system will be electrically or thermally led.
  • The impact that the main grid may have on the size of unit suitable for a specific location.
  • Whether the focus is maximising energy during high-demand times or creating an offset through thermal or electrical power.

Factors reducing CHP efficiency

When a CHP system produces heat waste that isn’t being successfully transformed into usable energy, the savings begin to reduce. The goal is to make use of as much energy as possible generated from the system. Alternatively, the heat energy produced should be exported into the grid, however, this doesn’t lead to direct benefits for your business. In order to maintain optimal efficiency, you need a unit that can manage expectations for demand and maintain them over an extended period.

It is important, then, to size a CHP unit to meet the baseload – the minimum level of demand required for both energy and heating over a given time frame.

Choosing the right sized CHP unit

To get a better understanding of the size of CHP units required from your business, take a clear analysis of your site’s energy consumption and demand over a period of time. Remember that energy is used in multiple places at any given time and a drop in any of these areas could have a significant impact on business productivity. If you can create a plotted chart of this information over the year or a series of months, you’ll gain a better understanding of the minimum level needed to keep everyone working at full capacity.

For newer buildings, it pays to consider the demands on similar-sized businesses and use these as a benchmark for considerations. Property developers should take note of factors such as occupancy factors and simulation modelling to do this. It pays to gain a clear understanding of the demands in a specific setting, especially during the times when it is running in real, everyday life.

Considering expansion and redevelopment

Businesses are rarely where they wish to stay and plans for expansion or the redevelopment of locations is likely on the horizon. Installing a CHP unit may be a required demand now, in advance of this. So it pays to forecast and consider how demand may grow during this period. Some companies will choose to initially size up with their CHP unit, understanding that the full savings won’t be made until the expansion goes ahead. Others will make allowances within the new designs and layouts for other CHP or energy-efficient heating units to be installed to meet the expected requirements.

Working with an experienced CHP provider is the best way to ensure you get the savings expected and the ROI you’ve forecasted for. Energimizer is here to help – get in contact or schedule a site survey with us today.