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All Electric ? Sustainability & Water Heating Pt.3

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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.

 

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Using The Sun – Sustainability & Water Heating part 2

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In this three-part series 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 part 1 we considered the role of air source heat pumps as a source of low carbon preheat, now we turn our attention to using the sun with solar thermal systems…

Read Part 1 Sustainability & Hot Water – Which Path Is Right For Commercial Properties? 

Using the sun to generate free heat from solar energy is a well-recognised and proven route for introducing renewables into a building project. As a high-temperature renewable source of hot water, solar thermal lends itself to working in conjunction with not only conventional gas heating but also other renewable technologies including air source heat pumps which can be used to provide pre-heat to solar thermal. This enables a variety of hybrid applications to be considered to meet the varied demands of commercial buildings.

Solar thermal systems are ideal for businesses that use and rely on large amounts of hot water, but it is important to understand that a solar thermal system will not fully replace your existing water heating system and will not provide space heating.

All areas of the UK are suitable for using the sun through solar energy technology; however, solar insolation, the energy generated from sunlight within collectors, will decrease as the sun’s inclination falls in the winter months and this is affected by how northerly located a building is in the UK as well as cloud cover. When it comes to using the Sun, solar thermal systems are obviously most productive in the summer months, when there is most sunlight, resulting in the additional need for either non-renewable energy sources or heat pumps which will still generate usable year round, even if ambient outside temperatures drop to -20°C during the winter months.

Shading from neighbouring buildings or tall trees, for example, can also greatly reduce a solar system’s output in which case a commercial air source heat pump would be a preferred alternative to produce low-carbon heat energy.

The actual percentage of your water heating demand covered by solar thermal will depend on your site and energy consumption habits (though this figure is typically around 30% for commercial sites). A south-facing and unobstructed roof with an inclination of 30° from the horizontal is optimal, though by no means essential as solar collectors can be installed in a variety of ways: built on the roof; built in roof; mounted on walls or on a frame construction to achieve inclination on flat roofs.

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.

It is important to recognise that solar thermal differs from solar photovoltaic or Solar PV as it is known. Solar PV uses solar cells in a panel to convert the solar energy into electricity that can be stored, used as required, and even be sold back to the grid. Solar thermal works by a process of fluid heating in the collector panels that is then transferred via indirect heating in the cylinder into the hot water system.  This requires basic plumbing for its installation and a minimum 3m drop to ensure flow. This does mean it is really only suited to installation on a building, rather than in the grounds, although that helps reduce the threat of vandalism compared to frames installed on ground level.

Giving consideration only to the hot water system, solar thermal is still more advantageous compared to equivalent-sized solar PV systems. For example, a 4kW solar PV system and the equivalent solar thermal system will cost almost the same to purchase and install, with minimal operational costs, but solar thermal will exhibit a much smaller physical footprint. A typical 4 kW PV system would require 16 collectors at 25m², whereas this would be matched by just three solar thermal collectors for a total footprint of 6.6m². This makes solar thermal a better choice for buildings with reduced roof space, especially if sustainable projects are intending to introduce a mix of solar thermal, heat pump and solar PV. The silent operation of solar is also a consideration factor.

To ensure system longevity and return on investment, fluid within the solar collectors must be correctly managed. If left in the panel it can overheat, stagnate and leave collectors irreparable. This can be avoided by incorporating Drain Back into solar system designs. This gravity flow approach reduces pump capacity requirements and energy use of the pump station to a minimum and will automatically drain fluid if power is cut without the need for working components. This makes solar thermal systems with drain back low maintenance with long operational lifespans. Fluid refresh is, on average, required every eight years but may last much longer.

Certain commercial system designs can demand a minimum of 45°C of preheat which, due to annual variation in production, could preclude the use of solar thermal as a lone preheat source. This does match the minimum working flow temperature for preheat that would be designed into a system utilising the current generation of air source heat pump.

Under such conditions, a typical sustainable application would see a cylinder sized to meet the storage requirements of the building’s hot water demands with the heat coming from a combination of an air source heat pump and solar thermal collectors working in conjunction to guarantee the preheat temperature. The heat pump, operating at optimal efficiency at lower temperatures will preheat the 5°C cold feed to 45°C at which point the solar thermal is employed to further raise temperature to 50 or 60°C depending on the time of year. Working together the renewables can offset the majority of the electrical costs otherwise required to heat the water, even during periods of peak demand.

Using the sun to provide energy to preheat a hot water application or top-up preheat in a hybrid hot water application is truly advantageous, but is not a singular response for the total hot water demand in commercial organisations.  In the third and final part of this blog series we will we consider the future of gas and the adaptation to all-electric applications…

 

 

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Sustainability & Water Heating

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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 to offset energy use in gas-fired systems as well as offsetting costs in electric/ASHP applications.

We will discuss this further in part 2

noise pollution

Noise Pollution – What You Need To Hear

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Noise pollution is a serious problem that can cause a variety of health problems and also be damaging to the wider environment. As such, its prevention will be a consideration for any design & build project in the commercial sector.

Noise management is a complex issue and at times requires complex solutions. Unlike air quality, there are currently no European or national noise limits which have to be met, although there can be specific local limits for specific developments. Furthermore, sound only becomes noise when it exists in the wrong place or at the wrong time such that it causes or contributes to some harmful or otherwise unwanted effect.

Unlike many other pollutants, noise pollution depends not just on the physical aspects of the sound itself, but also on the human reaction to it. Consequently, there is a range of legislation that addresses everything from clearly identifying sound levels of products to those regulating construction quality and setting acceptable noise sound levels within the working environment.

There are many causes of noise pollution. Traffic & construction noise is the most recognised sources of loud noise, but commercial machinery & equipment also contribute and are more likely to be a consistent generator of sound that over time becomes identified as a noise pollutant.

Noise pollution can have a number of negative effects on human health. It can cause hearing loss due to exposure to loud noise over a long period of time, but stress, anxiety and irritability, often associated with sleep disturbances is more common as will be a typical issue raised against commercial operations, especially if located close to residential land use. The disruption of local ecosystems and the impact on wildlife due to loud noise can also become an issue for a business.

The provision of hot water to commercial buildings is very often a business-critical function of daily operations and this can well be 365 days a year, so its important to give consideration to sound levels generated by the domestic hot water (DHW) plant. Fortunately, a typical gas-fired commercial water heater emits a conversational 55-65 decibels. This is further reduced with electric units, such as Adveco’s ARDENT electric boilers that produce just 35-58 decibels – quieter than an average conversation. To put that into perspective a domestic fridge will average at about 45 decibels, typical road traffic, heard from inside a car will rate at around 85 decibels.

Located within the plant room, this level of noise should prove to be of little concern. Many plant rooms will be located in basements or on separate floors, where noise is naturally muffled, or can be more acoustically controlled. The growing popularity of offsite constructed plant rooms, does mean these appliances are increasingly being located to maximise space in car parks, unused alleys and especially rooftops. This reduces the potential for noise pollution for the building’s users but could become an issue with neighbours as the GRP structures offer less capability to reduce sound. For boilers and water heaters, the noise as indicated is minimal and should not be an issue, but external baffles can be erected to deflect noise from any neighbouring structures.

Sound carries further when unimpeded, so the external location of commercial equipment is where there are likely to be issues, if any. With the drive to attain greater sustainability of systems, reducing carbon and offsetting more expensive electric energy costs, new DHW systems will take advantage of technology such as air source heat pumps (ASHP) or solar thermal to provide system pre-heat. Unlike gas and electric water heaters, this green technology must be located outside to operate. There is a major push for the UK to adopt ASHPs as a way to generate low-carbon heating, but concerns over noise remain one of the key stumbling blocks to their wider adoption, especially when applied to residential applications, whether domestic or across the leisure and hotel sectors.

Heat pumps will generate noise, due to the pump and fan rotation, and this can be a particular concern during night-time operation. At Adveco, we strive to research and manage our products to meet and exceed the criteria set by our customers, and much attention has been paid to the acoustics of our ASHP ranges. For example, at 52 dB(A), the Adveco FPi32 heat pumps are extremely quiet during normal daily operation, but also feature ‘quiet time operation’ to reduce noise pollution at night. This helps to address concerns, reducing outdoor noise pollution and improving the comfort of the working environment.

Decibel scale

 

Better still is Adveco’s near-silent solar thermal with drain back. An excellent way to achieve as much as 30% of the annual energy demands to run commercial DHW applications, solar thermal collectors required placement on the rooftop or external walls of a business. Because solar thermal drain back uses gravity flow for a large proportion of its operation, the system’s only mechanical aid is a small, near-silent pump. This makes solar thermal an excellent option for introducing cost-effective, sustainable water heating to a building without any concerns of generating noise pollution or having a project stall due to enforcement of noise regulations for external systems.

With the ever-increasing need for commercial companies to be more environmentally friendly, reduction of carbon and NOₓ emissions from the hot water application are going to top the agenda when it comes to new build or refurbishment, but addressing noise pollution should also be a consideration.

Gas & Sustainable Buildings

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The UK commercial sector is still very much in the early process of adapting to more sustainable working, with many still reliant on fossil fuels. Despite the calls to change to more renewable forms of energy many are continuing to refit with familiar gas technology, so what is the current state of play between gas and sustainable buildings?

Decarbonising UK commercial properties is an immense challenge. They are directly responsible for nearly one-fifth of the UK’s carbon emissions and, since domestic hot water (DHW) can account for as much as a third of a business’s routine energy demands, addressing emissions from hot water generation should be on an organisation sustainability agenda.

In response there are two broad UK-wide strategies: either installation of heat pumps to drive electrification, or, for properties on the existing gas network, switch over to hydrogen as a low-carbon alternative to natural gas.

In 2020 according to the Department for Business, Energy, & Industry Strategy (BEIS) more than 1,656,000 non-domestic buildings in England and Wales, the large majority of which were connected to the gas grid, were consuming more than 172 TWh of gas. The number of commercial properties is set to continue to grow, and though these new builds are opting for electric-only applications, existing buildings face a number of issues, not least the capital expenditure required to modernise services and the increased operational costs from implementation.

For this reason, unlocking the potential of hydrogen represents a familiar, easier and more cost-effective way to transition to more sustainable heating practices in buildings. The International Renewable Energy Agency (IRENA), recently estimated Hydrogen will cover up to 12% of global energy demand by 2050 from virtually nothing today. At least two-thirds of total production will be green hydrogen (produced with renewable electricity) with the remainder covered by blue hydrogen production (derived from natural gas) so long as the carbon capture and storage (CCS) is proved viable.

In the UK, the status of hydrogen remains to be confirmed as part of the government’s push towards attaining net zero by 2050. The Heating and Buildings Strategy published in late 2021 does, however, give an indication of the growing support for hydrogen-based technologies, as does continued government investment in its feasibility. Hydrogen, as a result, is increasingly seen as a core shift in the energy trade and critically, in the wake of demands to reduce dependency on Russian oil and gas, the future for regionalisation of energy supply.

Currently, when comparing average non-domestic gas to electricity tariffs, electricity will cost as much as four and a half times that of gas, making gas the more cost-effective option. Yet it fails to deliver a clear investment in sustainability unless hydrogen is used to decarbonise. That also comes with a number of advantages given the equipment remains familiar to operate and manage. It should ensure capital costs remain lower, while decarbonisation can be accelerated within a property.

For those wishing to adopt the hydrogen approach, there remains a question mark over how quickly, where and in what proportion hydrogen will be introduced into the gas grid. With the ultimate aim of introducing 100% green hydrogen via the existing gas network, gas water heaters and boilers will need to be factory configured to burn hydrogen only. Or be hydrogen-ready, whereby natural gas-compliant appliances can be converted to operate on hydrogen only in the future. These appliances, with the exception of some regional test deployments of hydrogen, are not expected to be actively used with 100% hydrogen until well into the 2030s at the earliest, with a potential national roll-out predicted for the 2040s.

As an interim, the UK is assessing the potential for introducing hydrogen into the existing gas network as a blend at 20% volume to deliver a safer, greener gas alternative that reduces carbon emissions. A blended gas grid has the potential to become a reality by the late 2020s, enabling organisations to become used to working with hydrogen as an energy source with less disruption and no noticeable change in how gas is used within the property.

Can gas & sustainable buildings still co-exist?

For commercial organisations which have recently invested in, or plan to refurbish, existing non-hydrogen-ready gas appliances, the most recent condensing gas-fired models currently on the market should already be able to burn natural gas with a blend of up to 20% hydrogen without requiring any modification.

For example, Adveco’s current ranges of high efficiency, ultra-low emission gas-fired condensing water heater, the instantaneous ADplus and semi-instantaneous AD, as well as the MD boiler range, are all hydrogen 20% blend ready. Such appliances give customers peace of mind when investing in gas-fired water heating applications. With the latest generation of gas water heaters and boilers offering more rugged construction and technology that better manages operation the working life of the appliance is further extended, meaning if purchased today they should continue to operate well into the 2030s. As hydrogen blending becomes commonplace, this then delivers on the desire to decarbonise operations in the easiest and most cost-effective manner as a business user. When these require replacement a wider choice of more advanced, proven and lower-cost hydrogen-ready and 100% hydrogen appliances for commercial applications will be available on the market as the gas network matures and greens.

Gas-fired commercial water heating, therefore, remains a proven and future-proof choice for the working lifespan of current-generation appliances. Not only practical and lower cost to operate, these also deliver a way to introduce a degree of sustainability in the interim before hydrogen can make a real impact so gas and sustainable buildings will develop hand in hand.

With modern building regulations, it is likely that a commercial hot water system, whether it uses gas or electricity, will still also require a low-carbon preheat source to reduce carbon emissions. For properties with an existing gas connection employing solar thermal can be extremely effective in reducing reliance on the existing gas boiler, cutting as much as 30% of the annual energy demands for water heating.

Fortunately, solar thermal also lends itself to working in conjunction with not only conventional or blended gas heating but also other renewable technologies including air source heat pumps. This enables a variety of bespoke, hybrid applications to be considered to meet the varied demands of existing commercial buildings.

Despite the reliance on fossil fuel, the latest generation of gas water heaters and boilers provide a realistic and lower cost option for organisations already connected to the gas grid to leverage technology that offers higher efficiency operation for lower energy consumption and critically ultra-low carbon and NOₓ emissions. Through integration with renewables, they offer a way to further reduce a building’s energy demands and emissions today, as well as the potential to act as a gateway technology to future greener hydrogen blend energy sources at no further cost.  For the next decade or so, they still have an important role to play meaning gas & sustainable buildings will remain a reality, especially if gas supplies can successfully transform from its fossil fuel origins to green hydrogen.

Solar thermal for commercial building projects requiring DHW

Solar Thermal For Hot Water Generation In Commercial Properties

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Adveco takes a look at the advantages of deploying solar thermal for hot water generation in commercial properties.  As part of an organisation’s wider sustainability plans, solar thermal offers a proven renewable technology that reduces emissions whilst able to integrate with other sustainable technology including air source heat pumps, direct electric and ultimately, through retained gas connections, hydrogen.

Commercial properties have traditionally sourced domestic hot water (DHW) from systems that have relied on gas boilers or water heaters because of the necessary high temperatures required for safe operation and the cost-effective operation it offers businesses. More recently there has been a trend toward all-electric systems in commercial new builds, driven by calls to support the government’s net zero strategy and cessation of new gas grid connections.

In 2020, according to the Department for Business, Energy, & Industry Strategy (BEIS), there were more than 1,656,000 non-domestic buildings in England and Wales. These properties are directly responsible for nearly one-fifth of the UK’s carbon emissions and, since DHW can account for as much as 30% of a business’s routine energy demands, addressing emissions from hot water generation becomes a key issue.

Whether a commercial hot water system uses gas or electricity, it will require a preheat source to reduce carbon emissions. Today there are realistically two main choices, either heat pumps or solar thermal. Neither technology offers a standalone response for the hot water system that will also require an alternate top-up heat source to meet minimum safe working flows of 60°C, peak demands and periods of low ambient temperatures or poor solar availability during winter months.

As a rule of thumb, new builds will invariably default to heat pumps, whereas properties with an existing gas connection will see greater advantages from the installation of solar thermal for hot water generation.

Currently, when comparing average non-domestic gas to electricity tariffs, electricity will cost as much as four and a half times that of gas. Even if a heat pump can demonstrate a 3 to 1 coefficient of performance (COP), and that needs to be for water with working flow temperatures of at least 45°C, that is not going to be enough to offset the difference in the cost of the gas-alone-fired alternative. Consider also that if direct electric is being used to top up the heat pump system and you are looking at an even wider divergence in operational costs.

Ideally allowing for approximately 20% solar fraction, or the percentage of the total thermal load satisfied by solar energy, employing solar thermal for hot water generation can be extremely effective in reducing reliance on the gas boiler.

Sizing Solar Thermal

Accurately assessing the demands and limitations of a building is critical for the correct sizing of the solar thermal system as the real world always seems to add unforeseen complexity. For instance, up to 25% of the total flat roof space available for solar panels will be limited by the allowance for access and prevention of shade which would otherwise compromise system efficiency. As building footprints become more compact and high-rise, especially in the case of city centres, available roof space to demand sharply decreases and solar thermal will come into competition with other heating and ventilation systems using the roof as real estate for installation. This is where solar thermal is more advantageous than solar photovoltaics (PV). Both approaches are directly comparable when used to offset direct electric water heating, with similar installation costs and annual savings. But in order to match three solar thermal panels taking up 6.6m² of roof space, a 4kW solar PV system will require 25m² to accommodate up to 16 panels in its system.

In general terms, each room in a hotel, care facility or education accommodation within an application design will require a 0.5 m² aperture, which is the area over which the solar radiation enters the collector. For flat plate collectors, the gross area and the aperture will be the same, with Adveco collectors, for example, each measuring 2.24 m². When sized and installed correctly, each solar thermal collector can contribute up to 1400kWh per annum, providing electricity savings of £300 electric and more importantly reducing emissions of CO² by 322kg. A commercial system sized to support an occupancy of 50 will typically require 12-24 panels, whilst smaller systems servicing up to 12 occupants will employ three to four panels. Collectively the panels deliver significant savings on the running costs that are not gained by using heat pumps.

There are also additional advantages that come with using solar thermal compared to heat pumps. Solar thermal operates silently meaning no sound pollution; there are no high global warming potential (GWP) refrigerants; and no specialist registration, such as F-gas, is needed for installation, although installers should be solar trained. A correctly installed and maintained solar thermal system will outlast a heat pump, and maintenance is low, especially if systems are deployed with a drainback capability.

Drainback

Using solar thermal for hot water generation works but capturing solar energy in a fluid that transfers heat indirectly to the DHW system. The solar fluid must be correctly managed, if left in the panel it can overheat, stagnating into a tar-like consistency which can leave collectors irreparable. Drainback is particularly important for preventing such overheating and resultant damage. It works by draining the fluid out of the system when not in use. This functionality is incorporated into all panels in Adveco solar system designs. Should the power be cut, the system naturally drains the fluid back to the reservoir, without the need for working components, providing guaranteed, low maintenance overheat protection. With such a system in place, solar fluid will last at least eight years before requiring a refresh. Drainback does require a 3m drop from the collector to the plant room to successfully operate, so the location of the plant room and the presence of flat or sloped roofs all come into play when calculating the most effective installation.

Hybrid Future

Fortunately, solar thermal also lends itself to working in conjunction with not only conventional gas heating but also other renewable technologies including air source heat pumps. This enables a variety of bespoke, hybrid applications to be considered to meet the varied demands of commercial buildings.  As solar thermal is (at times) a high-temperature renewable source, the heat pump should be used to supply the initial water heating from cold to 45°C. Solar thermal is then used after the heat pump to top up water temperature from 45°C. Any additional required energy would then be supplied by an immersion heater. This allows the solar to offset the immersion consumption, instead of offsetting the heat pump which already benefits from the COP. Although the solar will lose some efficiency operating at higher temperatures it is better because the COP is higher than the loss of efficiency.

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Building Sustainability Into Commercial DHW

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For more than fifty years, Adveco has been a leading innovator providing domestic hot water (DHW) applications for commercial-scale projects across the UK. Today its focus is shifting to encompass a blend of traditional and new, more renewable technologies in the form of solar thermal and especially heat pumps building sustainability into commercial DHW systems.

With a predicted one-third rise in non-domestic floor space by 2050, much of the current focus resides on new builds, but this still leaves more than 1.6 million pre-existing non-domestic buildings in England and Wales, generating almost one-fifth of the UK’s carbon emissions, needing expert, practical support.

Air source heat pumps (ASHP) have become the poster child technology for the government’s net zero strategy and therefore a core tool for building sustainability into commercial DHW systems.  The advantage of ASHPs is that, with performance greater than 100%, they can extract additional energy from outside of the building’s metered systems delivering significant carbon savings. For a commercial DHW system, it is recommended that a working water temperature from the ASHP, such as Adveco’s FPi32 or L70, must be at least 55°C. This is certainly attainable from current generation ASHPs when deployed in a hybrid approach. This uses the ASHP as preheat and combines it with either gas-fired or more preferably an electric top-up to achieve the required hot water temperature. This is where the additional system complexity and cost can creep in. But by correctly balancing a system through a mix of physical spacing in the vessel and system monitoring with dedicated controls, as developed for the Adveco FUSION, the system no longer fights itself, working seamlessly to deliver the highest operational efficiencies

In line with the European Commission’s proposal for a tightening of F-Gas regulations, development work continues at pace to support the introduction of R290, or propane as it is more commonly known. This refrigerant offers a coefficient of performance (COP) that enables working flow temperatures from an ASHP of up to 75°C and potentially much higher. This means future commercial systems can be less complex, without the need for additional electric immersion for high-temperature top-up and flushing for legionella protection. That said, immersions remain perfectly suitable for low-demand backup applications in boiler-fed indirect cylinders, ensuring business-critical DHW demands are met.

What we have seen more recently though is a shift in use, where immersions are used ‘directly’ in high-demand commercial applications as the primary heat source. An electric immersion heater has a high heat intensity compared to gas or indirect and, when coupled with high operating temperatures and hard water will increase the rate of scale formation which, over time, will cause the element to rupture.

In response, protecting a system from limescale is often only addressed by a vigorous cleaning regime. This method has a cost and downtime associated with it that is not acceptable for many commercial buildings.  For this reason, minimisation of scale formation with a water softener or a scale inhibitor may be adopted, but for many sites neither provides a satisfactory response because of space, maintenance, downtime, or cost.  A better option for these sites would be to replace the immersion heaters with a low-scale forming hot water system.

The new Adveco ARDENT electric boiler range provides a proven and cost-effective answer. Electric boilers still utilise immersion heaters located in a small tank heat exchanger within the boiler housing. This electric boiler supplies a sealed ‘primary’ loop to an indirect coil in the cylinder. The electric boiler heats the same water continuously so there is only a finite amount of scale in the system which will not damage the elements. The heat exchanger in the cylinder is a large coil operating at relatively low temperatures. Adveco’s extensive experience with indirect coil use in the UK has shown that scale is not a significant problem in these systems. The electric boiler operates at the same efficiency as an electric immersion heater (100%) so the only overall difference in system efficiency is the minimal pump electrical consumption and a small amount of heat loss in the pipework.

An electric boiler hot water system will take up a little more space than an all-in-one electric cylinder, but it has more versatility and requires less clearance for the cylinder. Similarly priced to an immersion heater, an electric boiler-based system will cost slightly more due to the small amount of additional installation work. But with virtually no maintenance and the cylinder forming significantly less scale, vastly improving reliability, the operational and maintenance savings will offset these additional capital costs. The electric boiler additionally offers a level of redundancy that is not achieved with a single immersion heater.

As the limitation on new gas grid connections for heating systems becomes effective this year, it will become critical for system longevity to recognise the new challenges electric-only presents over more familiar gas-based applications. If a business already uses gas, then it can still upgrade to new gas appliances until 2035, with 100% hydrogen-ready options extending that window well into the 2040s based on current appliance lifespan.

Adveco continues to support the refurbishment of existing buildings, recently extending its ranges of direct-fired condensing water heaters – the AD and the ADplus. Both ranges provide a compact, floor-standing design that is easy to introduce into an existing plant room to provide high-demand semi-instantaneous and instantaneous hot water applications.  Improved combustion efficiency means the burner requires less gas, delivering up to 30% savings in fuel consumption, making it more cost-effective, while reducing emissions.  For smaller on-demand needs, ADplus heats only what is necessary, with no ignition for smaller withdrawals providing considerable additional energy savings. Both AD and ADplus as a result exhibit ultra-low NOX (Class 6 appliance at 27 mg/kWh) and CO emissions (19ppm). With the government already committed to enabling the blending of hydrogen in the gas grid, it is also worth noting that these latest generation direct-fired condensing water heaters will already support the initial 20% hydrogen/natural gas blend.

Together, these technologies offer actual development arcs right now for existing commercial properties that are currently on gas, or new builds seeking to embrace low or no emission choices building sustainability into commercial DHW systems for more environmentally friendly operations that will help organisations achieve net zero by 2050.

Heat Pumps – The Cost Of Reducing Emissions

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With the government strongly advocating the use of heat pumps as a method of delivering net zero targets for commercial properties, we have noticed the trend for broad statements implying that while cutting emissions, heat pumps also reduce the energy costs for a building. It’s just not that simple argues Adveco’s UK sales manager Greg Brushett. So what is the cost of reducing emissions?

We strongly support the advantages of heat pumps as part of an all-electric or hybrid domestic hot water (DHW) system to achieve carbon savings. With DHW equating to as much as 20% of the total energy demand for domestic buildings and anywhere from 10-70% for commercial properties, it is important to clarify how heat pumps are being employed in a building’s system.

With a gas-fired system, you can achieve a safe DHW storage temperature without a significant impact on the overall efficiency but with a heat pump you need to either force the compressor to work very hard, which will reduce the Coefficient of Performance (COP) or, in a lot of cases, use the heat pump to partially heat the hot water and then use an immersion heater  – which has a COP of just 1.0 and therefore higher energy costs – to do the remaining work. If you are willing to accept this extra cost, working flow temperatures of 50- 55°C from the heat pump to an electric or hybrid DHW system are more than achievable year-round in the UK, and emissions will be dramatically reduced.

However, broad statements such as “heat pumps reduce costs” or “gas boilers remain more economic to run than heat pumps” are inherently misleading.

A heat pump can supply a properly insulated building’s heating system completely, and if designed well enough, can achieve a COP of 3.0, or slightly more, giving a similar yearly cost (within 10%) to that of a gas-fired heating system This would also be more attainable with the recent change in gas and electricity prices.

The same is not true of a hot water system. Following initial modelling and analysing reports from live systems a hot water hybrid system that achieves 50°C with an overall COP of 2.76 and uses an immersion heater to top up to 60°C has an overall efficiency of 2.4 based on the weighted average. Using these results, the running costs of the system are seen to be significantly higher than a gas system. However, the argument does demonstrate that incorporating heat pumps into an electric-only DHW system shows considerable savings over a COP of 1.0. Partnering this with other technologies such as solar thermal will only increase the benefits.

Benefits or efficiency?

Making the right choice between heat pump or gas depends on what an organisation is intending – whether seeking active emission reduction now, or, if already on gas, securing cost-saving operation until sustainable technology further matures, and costs fall.

Heat pumps can give incredible carbon emission savings for existing buildings, but as a way to reduce energy costs, replacing a gas-fired boiler/water heater with a heat pump doesn’t always add up. Commercial properties have unique demands, especially for DHW, making better application design and installation all the more important when it comes to specifying the right technology. Be wary of claims being made regarding the application of heat pumps, especially for the provision of DHW when it comes to calculating the cost of reducing emissions.

ADPlus instantaneous commercial water heating

Adveco ADplus Instantaneous Commercial Water Heaters

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  • A range of three compact floor-standing commercial instantaneous gas-fired condensing water heaters with built-in storage tank
  • Perfect for all water qualities with a 5-year warranty on burner and heat exchangers

Commercial hot water specialist Adveco, announces the Adveco ADplus range of high-power gas-fired condensing water heaters featuring an integrated 120-litre stainless steel water storage tank for instantaneous continuous and on-demand domestic hot water (DHW). The ADplus is available in three variants – 70 kW, 115 kW and 140 kW rated heat output.

“Designed to provide a compact, high capacity and reliable method for delivering instantaneous hot water to a commercial building, ADplus is a tough all-rounder,” said Bill Sinclair, technical director, Adveco. “It is perfect for a wide range of applications – from small instant demands to large-scale continuous DHW needs. With minimal NOX and CO emissions, the ADplus range is an eco-friendly way to serve your building’s DHW system. The rugged construction, supported by Adveco’s in-house warranty engineers, provides real peace of mind for your investment.”

The 115 kW and 140 kW ADplus variants offer two high-quality heat exchangers. Constructed from corrosive-resistant continuous run titanium-stabilised stainless steel, these provide balanced highly efficient operation and built-in redundancy. Heat is provided by the patented Fecralloy premix burner fed by a consistent balanced air/gas ratio at each point of turndown. The high modulation ratio results in high combustion efficiency with ultra-low NOX and CO emissions. A built-in flue back preventer on the combustion circuit prevents possible flue gas recirculation between different exchangers.

The tough, stainless steel 120-litre storage tank is provided with electronic anodic protection and high-quality polyurethane thermal insulation. This enables the ADplus to serve as a semi-storage system, providing always available and instantaneous supply with quick recovery times for continuous provision of DHW. For on-demand needs, ADplus heats what is necessary, with no ignition for smaller withdrawals providing considerable energy savings. When heat is required, the condensing technology provides up to 30% savings in fuel consumption. To reduce acidity build-up caused by the condensing process, the ADplus is equipped with a condensate acidity neutraliser, specifically sized to restore tolerable pH values. With the anti-corrosive construction, ADplus can be used with soft and softened water. For harder water, the recirculating pump regulates the correct water flow according to inlet water hardness helping to prevent the formation of limescale on the heat exchanger surface, ensuring high performance throughout its life cycle.

The extremely compact Adveco ADplus is designed to pass through a standard 65cm wide door for trouble-free installation and offers front access to all inner components for quick, easy maintenance. The integrated cascade controller supports full temperature control and self-check maintenance functions for up to 8 units. The controller accommodates 0-10 input, MODBUS communication, and alarm output for seamless BMS integration.

Additional Information

  • High capacity DHW production
  • Compact floor-standing arrangement
  • High-efficiency pre-mix burner with a five-year warranty
  • Extremely high-quality AISI 316Ti heat exchangers with a five-year warranty
  • Ultra-low NOX emissions, class 6 appliance at 27 mg/kWh
  • CO emissions 19ppm
  • High maximum run pressure up to 11 bar
  • Flue gas non-return valve for overpressure cascade flue systems
  • Standard flue systems using low-cost 110mm diameter PP
  • Available using natural gas or LPG

Read more about the Adveco ADplus instantaneous commercial water heater range 

keeping hot water flowing commercial buildings

Keeping Hot Water Flowing

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Keeping hot water flowing is critical in the commercial sector, where domestic hot water (DHW) appliances will be subjected to extremely hostile conditions, with high temperatures, thermal stress and flue gas condensate on the combustion side and oxygen, minerals and chemical attacks leading to potential corrosion on the waterside. Given this harsh daily treatment, regular servicing and maintenance are key if business-critical service is to be observed. Ensuring consistent operations and prolonging the life of a commercial hot water and heating system should therefore be a key factor when specifying and costing out these business-critical systems.

Once an application is sized correctly and installed, that maintenance process begins with commissioning. This choice falls to the customer, but Adveco advises that it should be engaged to commission its own appliances. This ensures product warranty commences from the date of commissioning, rather than the date of delivery which may be months before a system eventually goes live. If not commissioned by Adveco, it will also fall to the customer to fault find, order the new part and return the faulty part, which can be a painful, time-consuming process for any facility manager who is already time-poor.

Keeping hot water flowing to support consistent operations, we specialise in both commissioning and proactive warranty service to the manufacturer’s recommendations. This is crucial for the consistent and efficient operation of an appliance which can be affected by a range of environmental factors, water condition most notably, but air quality can also harm operation. The UK is broadly split between hard and soft water conditions. In naturally soft water conditions, despite the use of sacrificial anodes, glass-lined vessels can rapidly succumb to critical corrosive damage, making stainless steel the optimal choice, with longevity countering higher purchase costs. Commercial glass-lined steel water heaters and tanks are usually the more cost-attractive proposition in the UK, especially in harder water areas, where, given the right conditions, they are generally resistant to attack from most chemicals and less-corrosive materials. However, the deposition of calcium carbonate, or scale, found in harder water remains a key issue, whether opting for glass-lined or stainless steel vessels.

The latest generation of water heaters may incorporate recirculation pumps to balance the flow of water through the appliance’s heat exchanger. That balance is critical as higher flows can reduce calcification, but it can also lead to corrosion where that flow is interrupted or broken. This is why internal forms should default to curves within the design to provide consistent, unbroken flows.

In typical operation in harder waters, in our experience, it is almost impossible to completely avoid the build-up of scale. Magnets simply do not work properly, so the use of an inhibitor fluid is critical alongside regular annual servicing. This can be of a representative number of appliances on a premise, with conditions that reduce or extend that service period. Low levels of scale may allow for units to be serviced in alternate years for example reducing costs. That annual service must however be thorough.

Too many times an ‘annual service’ will be a quick test with an analyser and issue of a landlord’s certificate. Such activity is relatively low cost, as it avoids the purchase of a service kit, but is ultimately a false economy. It will miss the early onset of calcification and means the water heater or boiler is more likely to suffer early, terminal blockage. For a thorough annual service, we would advocate appliances be fully drained, visually examined and any scale be removed. The process involves disassembly which requires the replacement of rubbers and gaskets, hence the requirement to purchase a service kit. Though more costly, such full services are substantially cheaper than the cost of replacing blocked heat exchangers, burners and even the entire appliance.

If scale build-up is not addressed, then within five years any descaler fluid introduced will simply wash over the surface, which will also easily resist the most concerted of hammer blows. At this stage, the descaler will also not pass through the heat exchanger, requiring its complete replacement. This is seen when servicing or preventative maintenance has been avoided or forgotten, at which point the manufacturer’s warranty will be void.

Annual monitoring of the inhibitor system used for boilers is also key, especially if heating facilities have been refurbished within a building. It is not uncommon to see boilers damaged after radiators are replaced, and new water introduced into the system without replacing lost inhibitor fluid. Monitoring and replacement as part of the annual service activity will again protect the heat exchangers.

The other key failure point is the burner in gas-fired appliances. Condensing boilers and water heaters will draw air from the plant room and if that is dusty, it will be sucked in, reducing the efficiency. If not cleaned regularly, the burner will soot up and eventually become blocked often requiring full replacement at some cost. Even if located in an open space, or exterior to the building the burner should be thoroughly inspected. Nearby building works can cause high levels of dust, and in dense urban areas, pollutants from vehicles can also be drawn into the appliance causing build-up of dirt on the burner.

Serviced thoroughly and regularly, commercial water heaters and boilers should have an efficient operational lifespan of at least ten years (depending on location), and we do see appliances still operating for twice that length of time. The caveat in these cases though is that the overall efficiency of legacy units operating for more than 10 years will be far lower than current generations of appliances and will almost certainly fail to meet current ERP regulations on emissions introduced in 2018 for new water heaters and boilers. So continued maintenance of such units would not only be a false economy in terms of running costs but will certainly not be contributing to any efforts to introduce better sustainability in a building.

In short, failure to descale, flush sediment, clean burners, check anodes or test for corrosion will reduce the operational longevity of any appliance, but also severely impact the efficient operation. That has negative implications on operational costs and unwarranted capital implications if there is a catastrophic failure. Under such conditions, this will almost certainly invalidate any manufacturer warranty that exists. Reactive service providers will only check gas pressures and overall condition, they will then wait for breakdowns and call outs.  Only by keeping hot water flowing through proactive servicing can you ensure any costly downtime of business-critical hot water is absolutely minimised.

Keeping hot water flowing. Visit our warranty service page or contact us to arrange for your service.