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Getting Started With Sustainable Hot Water Systems

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Woman's hands washing in water in public washroom

Adveco offers some advice on introducing sustainable hot water systems into commercial buildings… To help achieve climate-neutral building stock by 2050 UK businesses are being challenged to reduce operational energy use. By increasing the use of renewable energy supply and prioritising on-site renewable energy sources the hope is to reduce harmful carbon emissions and improve the management of operational costs.  No doubt being more sustainable comes at a cost. Whether in the form of new build projects or the refurbishment of existing, yet ageing facilities, understanding the necessary capital investment, operational savings and payback periods is key to developing a realistic sustainability strategy. Starting the Journey with Hot Water Because of the ubiquitous need for hot water systems, from basins to baths and showers, catering and cleaning, addressing how this often business-critical resource is secured is one of the quickest, easiest and most impactful ways of making active carbon savings today.   Addressing the efficiency of domestic hot water systems (DWH) – whether through the implementation of heat pumps, solar thermal, direct electric water heating or even simple modernisation of existing gas appliances – helps properties meet sustainability goals practically and cost-effectively. It also delivers improved year-round conditions for customers and staff, providing spaces better suited to delivering quality services. For buildings already on gas and relying on large amounts of DHW, silent solar thermal preheat is preferable. For new build properties, the expectation is for specification to default to a mixture of heat pumps and electric boiler for afterheat. New system approaches, including prefabricated packaged plant rooms, also provide for better use of the spaces that already exist, without the need to undertake expensive and disruptive building projects. Don’t Plan Blind Whether designing new, or refurbishing existing hot water systems heating every building is different. So before embarking on any renovation work or transitioning from gas to electric, we recommend investing in non-invasive water metering. With accurate data comes better design, reducing capital investment, avoiding pitfalls of new technology and offering clear sight of future operational costs for improved strategic sustainability planning. Talk to Adveco about the design, supply, and service of low-carbon water heating for commercial properties.

Sustainable Schools: Learning About Low-Carbon Water Heating

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AO Smith gas water heating installed in UK school

Adveco considers how sustainable schools can take advantage of water heating to support the decarbonisation of the built estate… In the UK, the School Premises (England) Regulations 2012 require schools to have “an adequate supply of hot and cold water” in toilets and washing facilities, unfortunately, the production of hot water alone can drive as much as 30% of a building’s daily energy demands. Given space heating and water heating in buildings account for as much as 50% of the UK’s annual carbon emission implementing sustainable water heating, as it is a necessity, is one of the quickest and most direct methods for achieving measurable carbon reduction for sustainable schools. As hot water can be treated as a separate system it does not require the larger scale, costly renovations associated with space heating. This means schools can begin to make changes to current operations that immediately help to fulfil the demands of the Public Services (Social Value) Act. At its simplest, the government drive is to move buildings off gas and over to electricity. New build projects, unless exhibiting very large hot water demands which can often be found in school buildings, will struggle to receive permission (under Part L of the building regulations) for a new gas connection and as a result will specify electric-based systems. Continued use of gas, remains a grey area. Whilst not a sustainable option, it remains a cost-effective pathway to a future green gas strategy. Here in the UK, the status of hydrogen remains to be confirmed. The Heating and Buildings Strategy published in late 2021 did however begin to indicate the growing support for the technology. The implication for schools is, if you currently use gas, then you can upgrade to new high-efficiency gas appliances up until 2035. However, the EU states are pressing for all publicly owned buildings ‘in scope’ to have zero on-site emissions derived from fossil fuels from the beginning of 2028. If that happens then the UK may be pressured to follow suit.  If, from 2026, UK policy does support the adoption of hydrogen then the path should remain clear for education projects looking at unlocking the potential of hydrogen as one of the most cost-effective options for achieving net zero. The current generation of gas water heaters offers a high-efficiency, 20% hydrogen-blend-ready option that futureproofs systems until hydrogen policy is ratified and potential new green gas technology is rolled out nationally. Options For Sustainable Schools Today In the meantime, government policy has promoted the adoption of heat pumps, with the easiest to install and most cost-effective being air source heat pumps (ASHP). But this is a technology that operates most efficiently at lower temperatures, at odds with school hot water systems which require a 60°C+ working flow for safe operation and anti-legionella processes. A heat pump can however be pushed to deliver a higher percentage contribution, generating working temperatures of 45-50°C for preheating, but this at the cost of performance efficiency, requires electrical energy, and that again has operating cost implications. To accommodate this the simplest approach blends the ASHP preheat with an electric boiler supplying thermal energy to a mains water-fed compact indirect cylinder. Compared to an equivalent-sized direct-electric (i.e., from the grid) system, one with an ASHP can achieve carbon reductions of 42-47%, whilst saving 25-35% of the energy costs. With the heat pump’s reduced operational efficiency, it will still be much more expensive to run than an equivalent-sized gas-fired system. The recommendation in this case is to keep electrical demand down by increasing the size of the hot water storage which is then heated more slowly, very different to the high energy input and low storage seen with gas-fired systems. Further efforts to improve heat pump efficiency today can also be gained by specifying solar thermal collectors alongside the ASHP to guarantee the preheat temperature. Requiring a minimum three-metre drop to ensure flow does mean solar thermal is only suited to installation on a building, but properties with larger unobstructed flat or sloped roofs, such as schools, are perfect for locating solar thermal collectors. Not to be confused with electricity-generating solar photovoltaic (PV), solar thermal is a fluid-based system that transfers solar energy via indirect heating in the cylinder into the hot water system. The design of the system allows for the heat pump to contribute to the incoming cold water. That ensures 45°C while taking advantage of the coefficient of performance (COP) of the heat pump. The solar thermal is then employed after the heat pump to heat the water from 45°to between 50°C and 60°C depending on the time of year. Sized and installed correctly, a single solar thermal collector can contribute up to 1400kWh per annum, providing electricity savings of £300 and more importantly reducing emissions of CO² by 322kg. Whilst solar thermal can be deployed in isolation, by delivering hybrid preheat through both the ASHP and solar thermal system, demands on more costly electric heating are considerably reduced, if not avoided entirely. Given the current costs of electricity, solar thermal now offers a relatively fast return on investment and, since it is a capital expenditure it can, like the ASHP, contribute to positive sustainability reporting for sustainable schools. discover more about net zero and low carbon water heating for schools

Solar Thermal For Education Buildings

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Solar thermal collectors for school hot water

As the education sector is challenged to reduce energy demands to cut carbon emissions as well as trying to balance climbing operating costs, Adveco considers the advantages of adopting solar thermal for educational buildings as a means to meet more sustainable and cost-effective hot water requirements. Capable of offsetting typically around 30% of the energy demands for water heating, solar thermal systems for educational buildings is ideal since schools and colleges will rely on large amounts of domestic hot water (DHW). For the existing educational buildings, 80% of which are still expected to be in use by 2050, the application of solar thermal pre-heat is a well-established means of reducing demands on prevalent gas-fired water heating helping to offset operational costs and actively cut carbon emissions. New build or refurbishment projects, however, are now more likely to be mandated to adopt direct electricity but are finding that the move comes with a new financial burden as electricity remains substantially more expensive to operate than gas – currently by a factor of 3.8. Undisputed carbon and cost savings mean we are seeing a definite upswing in interest for new solar thermal systems where a ten-year return on investment is very achievable. A correctly designed and sized system will consider the daily usage and peak demands. Its aim is to serve all peaks from storage, with the size of the peak determining the size of pre-heat. The recovery time for peaks is what ultimately determines the number of solar collectors a building requires. The design process also sizes usage with available space. A south-facing and unobstructed roof with an inclination of 30° from the horizontal is optimal, though by no means essential as modern solar collectors can be installed in a variety of permutations. Unsurprisingly, solar thermal collectors do suffer if the building is significantly shaded, in which case a commercial air source heat pump may be a preferred option to produce low-carbon heat. If a school or college has a selection of unused flat rooftops then it is already at an advantage for using this technology. Modular, high-performance flat plate collectors can be situated on, or integrated into flat or sloped roofs, as well as mounted on a building’s façade. By far the most efficient way to heat water with solar energy, flat plate collectors offer a smaller footprint compared to equivalent solar photovoltaics (PV) for DHW. A typical 4 kW PV system requires approximately 16 panels covering 25m² of roof to match just three flat plate collectors covering just 6.6m² roof area. This makes solar thermal for educational buildings a prime choice when roof or facade space is limited.  Adveco collectors feature a copper meander absorber through which passes the solar fluid (glycol). The fluid transfers solar energy as heat to the system’s water via an indirect cylinder. To correctly manage solar fluid, drain back technology should be applied to protect the collector system from overheating. This can ‘cook’ the fluid to a tar-like consistency causing permanent damage to the collectors. As the name implies the solar fluid drains from the collector to a reservoir when not in use. Flat plate collectors with an integrated drain back module offer a more cost-effective (as there is no requirement for large solar storage) and more efficient (as there is no call to dump unused heat) approach. The technology has proven itself in the field with fluid changes required perhaps once in eight years, rather than the expected three. For new build properties with electrical connection, the gas heater is replaced with an electric boiler and cylinder to supply the afterheat which raises system temperatures to a necessary 60°C. This hybrid approach maximises the solar thermal input, typically offsetting 30% of the electrical demand, although it could be more depending on location. Adveco has simplified this hybrid approach by integrating a packaged Fusion electric water boiler system to supply the after-heat. This also gives the option of adding an electric immersion to the system as a backup for enhanced resiliency when assured water heating is deemed a critical service. The all-electric solar thermal approach further reduces carbon associated with grid electric systems and aids in lowering operating costs. This hybrid hot water system approach can be further extended with the inclusion of air source heat pumps to provide the initial pre-heat for the system. Operating at lower temperatures with the cold feed maximises the efficiency of the heat pump, reducing electrical operating costs and raising working flow temperatures from 10°C to 40°C. This is not hot enough for commercial applications, so the pre-heated water is then passed to the mid-solar thermal system. Essentially free to operate, the solar thermal system boosts the working flow temperatures from 40°C to at least 50°C. Although not operating at maximum potential, there is enough advantage gained from solar thermal to warrant the additional system complexity and capital investment. During summer months the solar thermal system can deliver the necessary 60°C working flow for safe provision of commercial hot water. But to ensure safe, consistent, and necessary high operational temperatures, the water is passed to the FUSION electric water heater. Here final consistent water temperatures of up to 65°C are assured year-round. To date, Adveco has designed and supports hundreds of hot water systems across the sector, often incorporating solar thermal for educational buildings. These applications encompass schools, colleges and university buildings across the UK. The outlined hybrid approaches are unavoidable if the education sector is to seek a sensible, practical, and cost-effective path to low-carbon hot water as part of wider net zero strategies. Visit our schools and higher education pages to learn more about sustainable water heating or contact us to discuss how we can help deliver on your sustainability strategy in a sensible, cost-effective manner.

Making A Sustainable Resolution For Public Sector Buildings

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Fusion electric hot water system with heat pump cylinder and electric boiler

Net zero is an immense challenge for the public sector, making 2024 an important starting point for a new sustainable resolution… Where do you start with sustainability? If this was an ideal world, we would know exactly what to do and all be producing absolutely zero emissions from all of our activities. But this is the real world, which means efforts will be hindered by myriad issues, not least technology and cost. For the near term, most public sector organisations will find absolute net zero either extremely difficult or next to impossible to achieve, so at present, most will be aiming for net zero emissions. With the government setting targets for other businesses to follow, ensuring the public sector raises its standards is essential. Government aim is to reach the net zero emissions target by 2050, however, there has been growing pressure on the public sector, reflected in the aims of the Public Sector Decarbonisation Scheme, to reduce emissions from public sector buildings by 75% by 2037 (compared to a 2017 baseline) as set out in the 2021 Net Zero and Heat and Buildings strategies. So making a a sustainable resolution is not just sensible it is being encouraged at the highest levels of government.  The latest tranche of grant money offered by the scheme will be up to £230 million, available through 2024/2025, with a budget for 2025/2026 expected to be at a similar level to fund heat decarbonisation and energy efficiency measures. Formal planned projects will have aimed for this grant funding, for which Phase 3c closed to new applications last November. For organisations which missed this application deadline, or suddenly find themselves facing unplanned requirements to heat buildings, some options can still be instigated sensibly and cost-effectively to support operational planning as well as making new inroads into greater sustainability across premises. The most common initiator for this sort of activity stems from failure in existing infrastructure, something commonly seen in legacy heating systems, especially where annual servicing or maintenance has lapsed through a need to make cost savings. Rather than a disaster, this can be treated as an opportunity to make small, but meaningful steps towards more sustainable operations. From the perspective as a supplier of hot water systems, the most common issue we see is boiler failures, especially at this time of the year when aging, inefficient systems are overworked and fail under excess strain. Many of these systems, which will be gas-fired can be well over 15 years of age and therefore retained beyond the recommended operational lifespan. The immediate option is to seek a like-for-like replacement, and although gas has become a dirty word in connotation with net zero, the reality is that modern condensing gas water heaters and boilers provide greater efficiency, demanding less fuel and thereby actively reducing carbon emissions and cutting operational costs. Most appliances will also be future-proof, offering out-of-the-box capability to accept a 20% blend hydrogen/natural gas mix. This allows gas-connected sites to be prepared to accept possible future green gas supplies via the grid. The other alternative is to consider reducing gas demands with renewables, such as solar thermal, or completely transitioning to an all-electric alternative. The latest innovative technology and processes can be seen in hybrid hot water systems that embrace heat pumps, solar thermal and electric boilers, allowing suppliers to support the sector in addressing the needs to achieve net zero, the circular economy and operational assurance. Better still, these alternatives rely on dependable, well-understood technology that can prove extremely cost-effective, both in terms of capital and operational expenditure. To ensure any project is successful, especially if transitioning from gas to electric, we would always recommend investing in a short data-collecting exercise. Low-cost and low-impact, Adveco’s Energy Saving Award-winning Live Metering service only takes a month but provides valuable data on existing system demands enabling accurate modelling of a replacement system. This almost guarantees savings, often considerable, and maximises any capital investment. With system data in hand, what are the best options for making a sustainable resolution? For the safe delivery of hot water, whether basin-led system or larger shower and bathing demands, flow temperatures in commercial systems are required to reach more than 60°C. Reaching these temperatures is problematic for the current generation of heat pumps, necessitating a hybrid approach. The heat pump operates most efficiently at lower temperatures, so is perfect for supplying year-round preheat to the system and offsetting the energy demands and carbon emissions of top-up heating supplied typically by an electric or gas boiler. Further energy offsetting can be gained through the integration of solar thermal, used to achieve the required higher operating temperatures. In the right location, solar thermal alone can offset up to 30% of your annual energy demands for hot water production, potentially providing all water heating during the summer months when the solar fraction is at its highest. It also lends itself to gas-fired systems as a means of offsetting fossil fuel consumption. Adveco has a deep heritage working with the public sector, developing often bespoke hot water systems for a range of buildings and usage. Recently it has been developing a pre-sized, compact and fast-to-install system called fusion which combines an electric boiler, a specially designed cylinder and the options of a monobloc air source heat pump and/or electric backup immersion, all with prebuilt pipework. Resilient, able to work with all water conditions and able to effectively eliminate limescale issues typically seen in hard water areas, FUSION offers a long-lasting alternative for refurbishment as well as new build projects. Compared to equivalent gas-fired systems, FUSION also delivers a reduction of up to 71% in carbon emissions, capabilities which recently earned Adveco an Innovation Award, as well as a Commercial Heating Product of the Year accolade. It’s just one example of how a relatively small, low-impact investment as part of a sustainable resolution can start to make a real change to the way a public sector organisation operates. Whether a school, healthcare, or public safety … Read more

IAQ in Commercial Buildings

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mould, virus and dust particles IAQ

Given that most of us typically spend up to 90% of our time inside buildings, indoor air quality (IAQ) is a serious consideration, especially as it relates to the health and comfort of the people who occupy it. Poor IAQ can have several negative health effects, including respiratory problems, headaches, fatigue, and allergies. It can also lead to decreased productivity and increased absenteeism. Despite hybrid working becoming firmly entrenched across the country, IAQ remains an especially important issue within commercial buildings, given the significant time people still spend within them, whether working or visiting. IAQ can be affected by a variety of factors, including the building’s ventilation system, the materials used in its construction, and the activities that take place inside it. The World Health Organisation (WHO) guidance on air quality has advised member states to consider air pollution to be as big a threat to human health and well-being as climate change and adjusted almost all of its previous maximum target levels for airborne pollutants downwards. It linked long-term exposure to even relatively low concentrations of ambient and indoor air pollution to lung cancer, heart disease, and strokes – putting the health impact of pollution on a par with poor diet and smoking. There are several things that can contribute to poor IAQ in commercial buildings. Some of the most common causes include: Many building materials, such as carpets, furniture, and paints, can release harmful pollutants into the air. These pollutants can include volatile organic compounds (VOCs), formaldehyde, and asbestos. Pollutants from activities that take place inside a building can also contribute to poor IAQ. For example, cooking, smoking, and using cleaning products can all release pollutants into the air. And if a building’s ventilation system is not working properly, it can’t remove pollutants from the air. This can lead to a buildup of pollutants and poor IAQ. When the Covid-19 pandemic struck, highlighting the role played by poor-quality indoor environments in the spread of viruses and other airborne contaminants, new standards were deemed necessary, elevating publicly available specifications in development by the British Standards Institute and BESA to a full British Standard BS40102-1. The new standard gives recommendations for measuring, monitoring, and reporting indoor environmental quality (IEQ) in all types of non-domestic buildings. It includes an evaluation and rating system for air quality, lighting, thermal comfort, and acoustics. Given that building retrofit work carried out to improve energy efficiency had, in many cases, led to poorer quality ventilation this new evaluation will give building managers a benchmark score to help them identify areas of below-par performance. This enables planned improvements which include IEQ measures in any retrofit and renovation work to improve the health and well-being of occupants. To meet the new standard organisations will need to tackle conditions that have a direct impact on human health including humidity, and excessive levels of CO2, CO, NO2, volatile organic compounds (VOC), airborne particulates and mould. Adveco has for many years operated a system of checks to ensure the comfort and safety of buildings, including initial system commissioning to ensure correct and safe installation of appliances, in particular its gas-fired water heating and flues. This is especially important in controlling and safely removing any CO2 and NOx emissions from proximity to building users. Regular annual service is a critical facet of such safety checks, yet can be a process that slips once products are no longer under their initial warranty period. This is both a false economy and of potential danger to building users. While new builds will embrace all-electric systems which effectively negate NOx and on-premise CO2  generation, pre-existing commercial sites need to be increasingly vigilant, especially when ageing gas-fired systems remain in use. Mould, a type of fungus which produces airborne spores, is also a contributor to poor IAQ so regular service also helps to identify or prevent cases of damaging corrosion (in soft water areas) and limescale build-up (in harder water areas) which can lead to leaks that then encourage growth of mould in plantroom areas. Setting IEQ performance benchmarks will make it easier for facilities managers to target problem areas, but British Standards will require further tightening if they are to keep abreast of the WHO’s more stringent guidelines. If you operate buildings with ageing gas-fired hot water systems and have concerns about IAQ or wish to reduce carbon emissions as part of a sustainability strategy, speak to Adveco about Live Metering, system assessment and replacement options. Whether looking for high-efficiency, ultra-low emission gas appliances such as AD / ADplus water heaters and MD boilers, or a transition to electric boilers, heat pumps or solar thermal we can help with system assessment, replacement design, supply and ongoing service for more efficient, comfortable and safe working environments.

Public Sector Decarbonisation Latest Funding Phase

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zero carbon footprint for the public sector

The UK Public Sector Decarbonisation Scheme (PSDS) is a government-funded program designed to support the UK’s net zero emissions target by 2050 by providing grants to public sector bodies to help them decarbonise their buildings. This is important as most of the buildings in the public sector still rely on burning fossil fuels for heating, hot water, and catering.  Phase 1 and Phase 2 of the PSDS have been successful in helping to decarbonise public sector buildings in the UK. The schemes have awarded over £1.75 billion in grants to over 1,300 public sector bodies, which have helped to decarbonise more than 2,000 public buildings. These projects have resulted in a reduction of more than 1.25 million tonnes of carbon emissions. Who can use the PSDS? The scheme is open to a wide range of public sector bodies, and it provides significant financial support for decarbonisation projects. If you are a public sector body that is looking to reduce your carbon emissions, the PSDS is a great option to consider. The PSDS is open to all public sector bodies, including central government departments, local authorities, schools, hospitals, police forces, fire and rescue services and other public buildings. The PSDS has been a successful program so far. In Phase 1, which ran from 2020 to 2022, the scheme awarded over £1 billion in grants to more than 1,000 public sector bodies. These grants have helped to decarbonise more than 1,500 public buildings, resulting in a reduction of over 1 million tonnes of carbon emissions. Phase 2 of the PSDS, which ran from 2021 to 2022, awarded £75 million in grants to a further 300 public sector bodies. These grants have helped to decarbonise more than 500 public buildings, resulting in a reduction of a further 250,000 tonnes of carbon emissions. Why should public sector bodies apply for funding? There are a number of reasons why public sector bodies should apply for funding from the PSDS. These include: Helps reduce fossil fuel emissions as well as making public buildings more comfortable and cheaper to warm.  To reduce their carbon emissions and help the UK reach net zero. To save money on energy bills. To improve the energy efficiency of their buildings. To create jobs in the low-carbon economy. Gain ongoing client and technical support on project delivery.  Phase 3c of the PSDS Phase 3 of the Public Sector Decarbonisation Scheme, worth £1.425bn, was launched on behalf of the Department for Energy Security and Net Zero in 2021 to supply grants to public sector bodies over the period 2022 to 2026. Phase 3c of the PSDS was launched this month. For Phase 3c of the PSDS, an additional financial year of funding has been granted by the Department. This funding increases the value of the overall funding to the scheme and will enable Phase 3c projects to deliver across two financial years. Phase 3c of the Public Sector Decarbonisation Scheme has up to £230 million available in 2024/25. The budget available in 2025/26 will be confirmed this autumn though applicants should assume a broadly balanced profile across 2024/25 and 2025/26. The Application Portal for Public Sector Decarbonisation Scheme Phase 3c is expected to open in the autumn and comes with soft sector caps (divided by Health, Education and Other) to ensure a more balanced distribution of funds across sectors.  Applicants can submit separate applications for separate projects or combine several projects for delivery across one or two financial years. Applicants can also include energy efficiency measures and other enabling works, that are additional to the replacement of the fossil fuel heating system, where they support a whole-building approach to decarbonisation.  To apply for Phase 3 funding visit the PSDS website or visit Adveco’s Net Zero resources to understand how funding can be used to support decarbonisation projects that deliver results today. For public sector buildings with gas-fired systems please talk to us about metering your buildings to understand how low-carbon technology can be successfully used to lower carbon emissions without excessively driving up capital funding.  

All Electric ? Sustainability & Water Heating Pt.3

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All electric banner

In this three-part series, Adveco has so far addressed the role of air source heat pumps and solar thermal as a source of low carbon preheat, in this final part, we consider the future of gas and the adaptation to all electric applications for implementing more sustainable hot water in commercial buildings.   Read Part 1 Sustainability & Hot Water – Which Path Is Right For Commercial Properties?  Read part 2 sustainability & Hot Water – Using The Sun Despite the pressure to address carbon emissions in building stock in the UK, the fact is we are still waiting for clear advice at a government policy level. The final decision on energy solutions remains unresolved. So do you opt to go all electric with equipment now on the basis that the grid will become zero carbon or hold out for the option of carbon-free gas such as Hydrogen, which in terms of infrastructure change and refurbishment would be potentially quicker, cheaper and less disruptive. As indicated, if your building has a gas connection and has high hot water demands it remains the most cost-effective option. Additionally, new gas-fired appliances operate with ever-reduced emissions, and most are ready to accept the initial proposed 20% hydrogen blends in the gas grid as early as 2024 without requiring any alteration. ‘Hydrogen Ready’ units are, with a replacement of the burner and pre-mixer, even capable of burning 100% hydrogen, but that scenario is some time away. Should hydrogen be accepted by the government as a function of net zero we would not expect 100% feeds to be in place nationally until 2040 with the grid changeover beginning in the early to mid-2030s. Retaining an existing gas connection, therefore, provides a degree of futureproofing should green gas technology be embraced. What is clear though is that the latest building regulations (Part L, 2021) have radically revised the carbon intensity of electricity from 519g CO/kWh ten years ago to just 136 today. Gas in the same period has fallen from 240 to 233. Whilst the regulations do not yet exclude gas, they do advantage the adoption of all electric systems. We have demonstrated that renewables have a critical role in reducing the carbon emissions of a system, as well as offsetting the costs of heating water with direct electricity. Gas-based hot water applications are, by a factor of 3.8, currently cheaper to operate than direct grid-electric systems. Using heat pumps can offset 25-35% of those energy costs, but this still leaves a considerable excess operating charge because of the need to provide top-up energy for safe operating temperatures. Historically, additional system top-up was provided by electric immersions, which for backup purposes and occasional peaks in demand whilst more expensive was acceptable. The shift to fully electric systems has put a greater onus on the technology which was never designed to provide primary heat. The costs are excessive and as we indicated, should they be deployed hard water, can rapidly develop scale leading to permanent damage in a remarkably short time. For this reason, we recommend the replacement of immersion technology with smaller electric boilers that are both more efficient, and, because they operate in a closed loop will avoid the issues of systems scaling up. Perhaps the most detrimental issue we see today as a result of replacing gas with electricity is the propensity to oversize the new all electric system, replacing gas appliances with electric alternatives with like-for-like capabilities. Hot water systems have been inherently oversized in the past through a lack of understanding of application design or concerns over providing suitable backup to ensure system continuity. The result of oversizing is however always the same, unnecessary capital costs for system supply and installation, but when replacing gas with electricity, oversizing leads to greater electrical demand and should that exceed a building’s available amperage of electrical supply, project installation costs will inevitably soar, or even stall the project. This can best be avoided by understanding your building’s actual hot water demands and designing the replacement to meet those specific needs. There is an art to designing hot water systems, but real, actionable data is priceless. When considering options for introducing sustainability the best advice we can give is to understand your needs first. Live metering is an easy, non-intrusive way of securing the valuable operational data you need to make informed decisions that deliver on expectations to lower carbon emissions without incurring unforeseen costs.  

Sustainability & Water Heating

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Sustainability water heating part 1 banner

In this three-part series on sustainability & water heating, Adveco considers the choices available to commercial organisations that wish to advance decarbonisation strategies in their buildings through the implementation of more sustainable hot water.   In this first part we consider some of the basic constraints of designing water heating applications, the technology available and the role of air source heat pumps… Which Path Is Right For Commercial Properties? Estimates vary, but it is generally accepted that buildings are responsible for as much as 50% of the nation’s carbon emissions, with much of the existing building stock still dependent on gas, which, while increasingly efficient to use is a ‘dirty’ fossil fuel. Daily hot water usage can potentially account for as much as 30% of a commercial building’s daily energy demands so is a notable component of an organisation’s emissions. So sustainability & water heating go hand in hand, and the latter should be one of the first considerations within a decarbonisation strategy. The relatively lower cost of gas compared to grid electricity, and the necessary high working flow temperatures it delivers have therefore made it historically the energy of choice. This becomes problematic if sustainable operations are now the goal. As a matter of course, new builds, unless exhibiting large demands for gas, will struggle to receive permission (under Part L of the building regulations) for a new gas connection and as a result, are going ‘all electric’ for heating and hot water. With modern construction fabric and insulation, this approach can pay dividends. For legacy properties requiring refurbishment, the choices become more problematic, especially for space heating where modern low-temperature systems need replacement pipework and heat emitters or will fail to deliver. Though this is not an issue for replacement hot water, the complexity of both new build and refurbishment can still suffer costly pitfalls in the drive to sustainability. With electricity on average currently costing as much as 3.8 times that of gas, serious consideration needs to be given to a selection of technologies available to ensure that any changes to a hot water system balance the carbon reduction with the capital and operational costs. The Options For Sustainable Water Heating There are several options when it comes to implementing a hot water system and as we have intimated some are driven by finance others by the desire to be environmentally aware. Other factors though can include everything from geology to available space. A building’s location will instantly direct certain decisions as the hardness or softness of the water will impact options. For instance, stainless steel cylinders will be preferential in soft water areas as they are resistant to the corrosive nature of the water, whilst lower-cost glass-lined vessels are preferable in harder water areas. However, high-intensity heating, such as delivered by electric immersion can be extremely detrimental in hard water regions, accelerating limescale generation to the point that it can irreparably damage a system in a matter of months if not correctly maintained. That does not preclude electricity as a choice, but it does affect how applications should be designed. The real leading question is do you choose gas or electricity? If gas, do you opt for direct or indirect heating systems or if electricity do you choose immersion or electric boiler as your source of thermal energy? Whichever route you decide upon, your system will additionally require a low-carbon heat source which will preheat the water reducing the energy consumption of the water heater, and in turn, reduce carbon emissions and the running costs of the water heater. There are several choices for securing low carbon heat, including biomass; combined heat and power (CHP); ground or water source heat pumps; air source heat pumps (ASHP), solar photovoltaics (PV) and solar thermal.  Through a mix of cost and simplicity, the best technologies to use for domestic hot water (DHW) systems are either ASHP or solar thermal. Heat pumps are a technology that operates most efficiently at lower temperatures, making it highly applicable to domestic applications, but commercial DHW systems require 60°C working flow for safe operation and anti-legionella processes. The heat pump can be pushed to deliver a higher percentage contribution, generating temperatures of 45-50°C for preheat, but this at the cost of performance efficiency, requires electrical energy, and that has operating cost implications. Compared to an equivalent-sized direct-electric (ie, from the grid) system, one with an ASHP can achieve carbon reductions of 42-47%, whilst saving 25-35% of the energy costs. The system will still be required to top up heat to the necessary 60°C, using either immersion or an electric boiler. This, combined with the heat pump’s reduced operational efficiency means it will still be much more expensive to run than an equivalent-sized gas-fired system based on a modern and efficient (109% net) water heater. The recommendation, in this case, is to keep electrical demand down by increasing the size of the hot water storage which is then heated more slowly. This is very different to the high energy input, low storage seen with gas-fired systems. A 30kW energy source can heat 750 litres/hour by 34°C, so when the system draws hot water at a faster rate than it can be heated to 44°C for hot showers you start to get complaints that the water is ‘cold’. The larger volume cylinder helps to overcome this undersizing allowing for a two-hour reheat cycle that maintains enough water at 60°C to meet daily demand, whilst slowly heating reserves through the night when demand is minimal to meet the morning peak. Despite gaining improved sustainability & water heating modernisation the carbon savings and costs no longer align. Even with an ASHP operating at optimum efficiency (for 35% recorded reduction in energy) costs would be close to three times that of gas alone, so it is inherently important to consider the nominal value of the carbon reduction when planning a refurbishment from gas to electricity. However, we can still take advantage of solar thermal which can be employed … Read more

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Adveco - Experts in commercial hot water systems.

Adveco Ltd. is the sister company to Adveco (AWP) Ltd, trading as A.O. Smith Water Heaters in the UK and has more than 50 years of expertise in the building services industry.

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© Adveco Ltd 2024

© Adveco Ltd 2024