Berry Court care home plant room installation.

The Cogeneration Gap – Part 3 Caring for the Environment

We have considered the reasons for implementing m-CHP in new builds and upgrading care homes. In this third and final blog in the series, we consider one last deciding factor, the environmental impact of local cogeneration…

The carbon savings have long been an advantage of Combined Heat and Power (CHP), and can still be achieved, but that is changing because grid-supplied electricity is getting much cleaner. There has been a strong downward trend in emissions from electricity production since 2014, due to the increases in wind and solar power and the closure of coal-fired power stations. But on average, CHP provides a carbon benefit over the year, though the actual intensity fluctuates both seasonally and daily. On most days where carbon intensity is more than 188g/kWh CHP will provide a benefit. CHP will be carbon advantageous at some times of the day and not at others, but looking at the average carbon intensity of electricity generation from 2013-2017 even in the summer months when demand falls, the carbon intensity never fell below 200g/kWh, so CHP was always beneficial in this period in terms of carbon savings. Carbon intensity of the grid is higher when it is dark and cold, and CHP requires a thermal load to operate so naturally aligns itself with the higher carbon intensity when it provides greatest impact and savings.

In the future smart controls will adapt CHP run times to ensure it operates when it is most carbon advantageous.  For a CHP that runs for 14 hours per day, for example, the smart controls will ensure that the 10 hours when it does not operate align with the clean grid periods and not when the carbon intensity is the highest.

Even so, we recognise that the value of carbon savings with CHP will continue to reduce in comparison to previous years. Instead, attention is now turning to Nitrogen Oxides (NOX) savings. A by-product of the combustion of hydrocarbon fuels, NOX are a major contributing factor to poor air quality, the most toxicologically significant being a combination of nitric oxide (NO) and nitrogen dioxide (NO₂). It can cause lung irritation and respiratory infections as well as being linked to cancer, asthma, strokes, and heart disease. The Royal College of Physicians believes it directly leads to as many as 40,000 deaths each year. This has led to widespread recognition that more needs to be done to address NOX emissions and the care sector needs to be seen to be addressing emissions that are a by-product of its activities.

Although all CHP with a catalytic converter is cleaner than the grid, taking in to account electrical efficiency, the wider CHP industry, as an average, has the same NOx emissions as large scale power generation. The downside for CHP has been that carbon-based power generation historically was located outside of major urban areas, but the drive for low carbon buildings is bringing even more potential emissions into our cities. Most CHP are likely to have a slight positive impact on air quality nationwide, but because those installations will typically be in urban/residential areas that CHP will have a negative impact.

Therefore, localised NOX emissions from ‘dirty’ cogeneration is becoming a concern. Where CHP is used to offset condensing boiler run hours, if the CHP is dirtier than the condensing boiler then the local emissions are worsened. Despite air pollution and NOX mainly arising from road traffic – half of current NO­X pollution in major urban areas is attributed to vehicles – emissions from decentralised energy production are now being seen as a contributing factor. It is therefore of great importance that the NOX emissions from new CHP units are lower than condensing boilers if they are to have a positive effect.

Our own assessment of cited NO­X emissions from CHP manufacturers shows wildly fluctuating numbers, ranging from 64 mg/kWh to a highly concerning 596 mg/kwh, and older units were far worse. Consider the 2018 EcoDesign limit for CHP is 240mg/kWh! And I would argue that this number is now far too high given the changing attitude to, and awareness of the dangers of NO­X emissions.

Despite heat recovered by the CHP being considered NOX neutral, it is vitally important to recognise that there is a considerable difference between ‘dirty’ CHP and the latest generation of low-NO X CHP. One such class of low-NO X appliance are the micro or m-CHP units, where we can cite emissions levels as low as 11mg/kWh. For a unit of 20kW electrical output, with a gas input of 70kW, in a situation with an average annual run time of 6,500 hours for a standard application such as a care home, the yearly NOX emission from a ’dirty’ CHP will be 109.2kg/year, compared to 4.55kg/year for the latest generation of m-CHP. And remember, this option is also improving local air quality because the m-CHP is used to offset the run hours of a condensing boiler which at emissions over 30 mg/kWh is dirty compared to the CHP.

Conclusion

Comparing CHP with other local energy generation technologies, today we can still show that it has lower running costs than a heat pump, plus has both higher savings and an easier install than PV. Without doubt, a CHP can provide useful energy cost savings for a building, so it always makes sense to run existing CHP, and makes sense to purchase for the right type of building.

Mid to high occupancy residential care homes are particularly apt and upgrading to CHP in these facilities will provide a good payback period and be a solid investment over the decade, so long as a guaranteed maintenance schedule is put in place.

Finally, selecting the right CHP can provide carbon savings and more importantly, as we look to the future, can help improve local air quality for a building.

At the end of the day, the building and its use should drive the decision making, but for the care home, perhaps the greatest advantage of all is the assurance that residents will have a continuity of comfort through the provision of heating and hot water. It is in this role that m-CHP delivers a business-critical need in the care home environment.

TOTEM T20 CHP unit (Combined Heat and Power unti) in a residential care home.

The Cogeneration Gap – Part 2 Embracing CHP

In the first part of this short blog series on the application of micro-CHP within residential care homes Adveco explained why CHP (Combined Heat and Power) is often chosen for new builds. In this second part, we turn our attention to why you would upgrade existing facilities to m-CHP…

The cost of deploying CHP within care homes is, without doubt, the deciding factor for the majority of managers. When calculating the operational cost savings, we need to take the cost of the offset electricity and thermal energy, and deduct the costs of the energy coming in, in other words, the price of the gas, and the maintenance costs. The other key input is the number of run hours per year that the CHP appliance will operate.

A CHP is very different to a boiler, which other than an annual service you would typically tend to forget about. Inside the CHP casing is a gas-powered automobile engine, with high stressed moving parts that will require necessary repairs over time that could reduce savings. So, you need to be aware of the ongoing investment needed when operating CHP to support regular pay as you go maintenance and repair. Once the cost of maintenance is factored in, the operating costs can be determined based on electricity and gas prices.

To understand what these operational costs look like, I am going to cite current figures based on the installation of a TOTEM T25 micro-CHP unit. From our experience, these are typically the size of a unit a larger care home will install. Firstly, being gas-powered, the CHP is a far better option when the cost of gas is less than electric, which has been the trend since 2015. Currently, based on medium non-domestic rates, a T25 will save £1.50 per hour that it runs. Let’s consider the expectation on run hours per year, many CHP units that have gone in will run relatively short hours per year just to increase the efficiency of the building to meet carbon requirements. Looking at the demands of the London Plan, for example, 2,500 run hours may be sufficient to meet the additional carbon savings demanded. At that lower run rate, the CHP is still going to save £3,750 savings per year.

This may not be enough to provide a true payback, but are interesting savings in an inherited, new building, where the cost of the CHP is part of the cost of the building and does not have to be proven to pay back. The decision is only to run it and save £3,750, or not and save nothing.

Upgrading to CHP

But what if you want to upgrade your plant room, when is right to Include CHP? The technology offers a number of advantages, the micro-CHP is especially easier to install, passing through a standard 60cm doorframe and able to be installed internally, avoiding the need for external space or rooftop placement which would be needed for say solar photovoltaics (PV) which is another common choice for onsite energy generation. CHP also offers better payback than Air Source Heat Pumps (ASHP) and with inclusion in the Government’s new SEG payments, you can profit from additional energy generated by selling it back to the grid from your CHP at a guaranteed tariff. There is also the bonus of increased resiliency for your DHW and then there are the running cost savings.

The cost of a T25 is £50,000, with savings per hour (including maintenance) of £1.50, so it requires 33,333 run hours to achieve payback. Saving just £3,750 per year means the only driver is carbon savings and that would not alone warrant the investment in an existing building.

If the building is right for CHP, then it is worth considering as an upgrade. CHP saves money when it runs, it’s the opposite of a boiler which costs money when it runs so we want that to be off and the CHP on.  The ideal applications are ones with large DHW loads where people are residing. With a large care home, the expectation would be to run a CHP 24 hours per day during the heating season, dropping to 12-14 hours per day outside heating season. This gives us an average running of 18 hours per day throughout the year or 6,700 run hours per year. That equates to a five-year payback, and with 10-year  operating plan in place the potential savings will be £50,000 if your building is suited to the technology.

Alexandra House, operated by Care South, is a two-storey, 58-room residential care and nursing home in Poole, it has a T20 CHP working in conjunction with a custom-built 2500-litre buffer vessel, as well as a cascade of two AO Smith Upsilon 110 boilers and two AO Smith IT500 indirect calorifiers. This is all supplied as a complete package, alongside ancillaries and backup heating components via electric immersion elements. The design of the hot water and heating system at Alexandra House is projected to achieve more than 7,100 CHP run hours per year, resulting in annual carbon reductions in excess of 44.5 tonnes and providing expected energy savings, inclusive of CHP maintenance costs, of £7,500.

In the third, and final part, we will take a look at the environmental impact of m-CHP and explain how it can deliver energy and heat whilst reducing a care home’s emissions…

CHP for residential care homes (Combined Heat and Power).

The Cogeneration Gap – Part 1

Often seen as an ideal application within the residential care home, in this short blog series Adveco discusses the argument for onsite energy cogeneration, the operational costs, the environmental impact and highlights the increasing performance gap between ‘dirty CHP’ and the latest generation of highly efficient micro-CHP…

Whether building a new residential care home or refurbishing an older property to be fit for purpose, the importance of energy provision has risen up the agenda, resulting in a proliferation of on-site power generation. According to a report by Centrica Business Solutions (The Energy Advantage Report, June 2018).

“…more than 80% of commercial operations are expected to invest in on-site power production to generate up to a quarter of their electricity requirements by 2025.”

One popular choice has been the deployment of combined heat and power (CHP), also known as cogeneration. This is the simultaneous production of usable heat and electricity from a single process and source of fuel (typically gas) and is one of the most effective methods available to significantly increase the energy efficiency of a building. With an engine directly coupled to a generator, similar levels of efficiency to that of a conventional source of power can be achieved, and by locating such an installation on-site at the point of consumption, the usual energy losses associated with power transmission through the grid are eliminated.

Additionally, thermal energy is extracted from the CHP process by recovering the waste heat produced by the engine and generator during the power generation process. This drastically reduces the amount of fuel energy lost to the environment as exhaust, instead using it to contribute towards a local heat demand. With a significant continuous demand, such as would be typically seen in a residential care facility a CHP unit can run for very long periods of time and thus drastically reduce the reliance on conventional boiler technology and improve the overall efficiency of a building, reducing emissions and making financial savings.

Understanding the advantages of CHP

For operators and managers of care facilities, there are two basic questions to ask. If you have CHP what should you do with it? If you don’t, should you upgrade your plant room to include CHP?

I want to make it clear that in my opinion there are enough benefits that you definitely want CHP, but you may not want to buy it outright. CHP will have an environmental and cost savings impact in any building, but it only provides a payback case on Capex in the right type of building. That is why you may not want to invest in the technology.

If your building already has CHP it is because someone made the decision to select Combined Heat & Power based on either a financial or an environmental reason. But there are notable differences in between those who design, and those who operate the building.

Designers have historically chosen CHP based on carbon savings requirements from things such as Part L, or the London Plan, which other UK cities will mirror, rolling out their own equivalent local environmental policy.  Designers need carbon savings to get planning permission for a project to be built. It is the most important thing for the designer, and it is the minimum that must be done to successfully complete their job. That is why the designer selects CHP. If you inherited a building built in the last five years with CHP, then it was probably selected for SBEM carbon savings to meet Part L.

So, in this scenario you have CHP, but if it was installed purely for carbon savings, then we have to accept that may not be the most important thing to the end client and their facilities management team. Foremost is the functioning of the building, so the priority is the reliability of supply of heating and hot water, next is the operating costs of the building, and this is then followed by environmental concerns like NOₓ and carbon emissions.

It needs to be recognised that CHP is a support technology, as opposed to a critical technology. Water heaters and boilers are critical equipment, if they break down it influences the heat and hot water supply to the building, and therefore the comfort and safety of the residents. CHP, like many renewables, makes no difference to the reliability of the supply. Whether it is on or off the building still has heating and hot water. If you have inherited a CHP, then you need to decide what you want to do with it.

Shutting it down is an option. You could turn it off and forget about it.  If you do that then you will pay no maintenance, nothing for energy consumption by the unit and, there will be no loss of heat or hot water supply. You will not have any carbon savings either, but, since the building regulations are not policed you can, unfortunately, do this.

Alternatively, you can pay for maintenance and energy and then start reaping the rewards of operating the CHP. Rather than using just gas or electric water heaters for all the domestic hot water (DHW) needed for washing, cleaning, showers and baths, the CHP will supply heat captured from its operation to warm, or preheat stored water. The CHP can supply as much as 90% of the hot water needed by the care home with the water heaters used to ‘top-up’ the water temperatures and meet periods of high demand for Part L systems. CHP is also a great way to build a guarantee of consistent hot water service. Typically, a care home system will operate two or more water heaters, but should one fail it would result in a reduction in available hot water. With the addition of a CHP able to preheat at least 60% of a care home’s hot water needs, residents and staff should not see any obvious change in their hot water services should a water heater fail.

In part two we will consider the cost of operating CHP and gauging when and if you should look to upgrade to the technology…

Legionella Precautions When Reopening Buildings

Legionella Precautions When Reopening Buildings

  • Find the Legionella risk assessment for your building.
  • Restart hot water systems 24 hours before the building is to be reoccupied.
  • Test water temperatures.
  • Get expert advice if a building’s occupants’ health places them in a high-risk category.

Commercial hot water and heating specialist, Adveco, today offered a precautionary warning against the dangers of Legionella for businesses planning to open facilities under the Government’s ‘conditional plan’ to reopen society.

“In response to Covid-19, an unprecedented number of business properties have been forced to close, often with little to no warning. As those businesses work towards reopening it is extremely important that some consideration is made to how to restart it without creating an unsafe situation if buildings have been shut and the hot water has been turned off,” advises Bill Sinclair, technical director, Adveco.

Stagnant (not moving) water, especially at warm temperatures (more than 20°C), creates the ideal situation for the proliferation of Legionella bacteria.  Normally in hot water systems the risk is minimised by the temperature, constant flow and because the risk of Legionella in the incoming mains is relatively low. However, it can be present, and the risk to building occupants increases if: a water system is fed from a cold water tank instead of the mains; a hot water system has been turned off for more than a week; there are aerosol creating taps such as showers, whirlpool Jacuzzi hot tubs, washing up spray faucets, and any building where occupants are elderly or immuno-compromised.

If a business has been closed, and the hot water system has been off, and the building taps are mains-fed and occupants are low risk and then it should be sufficient to do the following:

  • Find the Legionella risk assessment for your building and read it thoroughly
  • Start up your hot water system at least 24 hours before the building is to be occupied
  • Make sure all pumps are on
  • Make sure the hot water temperature is over 60°C

Wait a few hours, or better still next day carry out the following:

  • With a thermometer, check the temperatures from several non-blended taps that are as far as possible from the water heating system. They must achieve temperatures of more than 50°C within 60 seconds, and preferably hotter and faster
  • Run all hot and aerosol creating taps to thoroughly flush them. The minimum expectation for small, basic hot and cold water systems would be flushing through with fresh mains water.  During flushing, all valves should be operated in the fully open position so that any particulate matter can be flushed through. For larger buildings with tanks, showers, calorifiers and more complex pipework, more extensive flushing is recommended. Due to the recent warm weather, it is likely that some increase in bacteria levels and biofilm will occur. Depending on circumstances, sampling and testing for different bacteria may be recommended and the system will require cleaning and potentially repeated disinfection. It is still good sense to have evidence that this process has been successful, so sampling in accordance with BS7592 should be considered to validate the effectiveness of flushing and cleaning.

If your hot water system has been off, and your building taps and occupants are medium or high risk then you must do the following:

  • Find the Legionella risk assessment for your building and read it thoroughly
  • If you have a maintenance team with expertise in Legionella you should contact them before restarting the hot water system
  • If you do not have such a team you must take advice from a firm that does or contact Adveco Technical Support for further information

It is important to remember that the responsibility for Legionella control lies with the duty holder. The temporary building closures as a response to Covid-19 means that unless careful consideration is given to restarting hot water systems there is a real potential for a Legionella outbreak.

For further guidance on reopening your business and the threat of Legionella refer to this information from ICOM Energy Association.

About Adveco

With almost 50 years of industry experience, Adveco is the trusted specialist provider of bespoke hot water, heating and power systems to the building services industry. Committed to partnering with its commercial and government customers, Adveco helps create comfortable, efficient, functional, safe and sustainable buildings through invaluable support in the design, supply, commissioning and service of business-critical hot water, heating and power. Headquartered in the UK, the company operates across Europe from offices in the Netherlands and Belgium.

Adveco – Expertly engineered for you. Visit www.adveco.co