Welcome to the Adveco February 2023 newsletter covering Net Zero in review, healthcare hot water, and more award wins for our work with heat pumps for hot water applications designed for commercial properties…
Welcome to the Adveco February 2023 newsletter covering Net Zero in review, healthcare hot water, and more award wins for our work with heat pumps for hot water applications designed for commercial properties…
As a leader in the design and supply of solar thermal applications for the commercial built environment, Adveco looks at why the technology remains one of the best ways to decarbonise hot water without driving up operational costs.
Solar thermal applications deploy panels with fluid that captures and efficiently transfers solar energy as heat indirectly to the domestic hot water (DHW) system. As a high-temperature renewable source of DHW, Adveco solar thermal lends itself to working in conjunction with not only conventional gas heating but also other renewable technologies including Adveco’s air source heat pumps which can be used to provide pre-heat to solar thermal. This enables a variety of bespoke, hybrid applications to be considered to meet the varied demands of commercial buildings.
Whether a commercial hot water system uses gas or electricity, it will require a preheat source to reduce carbon emissions.
As a rule of thumb, new builds will invariably default to heat pumps. In contrast, properties with an existing gas connection will see greater advantages from the installation of solar thermal which can be extremely effective in reducing reliance on the gas boiler. Even so, offsetting costs in direct electric systems through use of solar thermal applications remains extremely advantageous.
Neither heat pumps nor solar thermal technology currently offers a standalone response for the year-round high temperatures, high volume and peak demands seen in commercial systems. Solar thermal can be combined with a heat pump (which is used to supply initial preheat) to top up heat to a minimum of 60°C required for commercial applications without using direct electric immersions.
A more compact alternative to solar PV for DHW, solar thermal is extremely advantageous where roof space is at a premium due to competition with other heating and ventilation systems on a project. This is especially true of urban projects where solar thermal’s silent operation is also desirable.
Whichever approach is chosen, making an accurate assessment of the needs and limitations of a building first is critical for the correct sizing of the solar thermal system.
A commercial system sized to support an occupancy of 50 will typically require 12-24 Rugged 2.24 m² flat plate collectors, whilst smaller systems servicing up to 12 occupants will employ just three to four panels.
Sized and installed correctly, each Adveco solar thermal collector can contribute up to 1400kWh per annum, providing electricity savings of £300 and more importantly reducing emissions of CO² by 322kg.
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. Adveco solar thermal systems avoid this by incorporating drain back into all its 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 drainback low maintenance with long operational lifespans. Fluid refresh is, on average, required every eight years but may last much longer.
With more than 800 systems deployed across the UK, Adveco’s solar thermal applications are an effective renewable which today offers clear cost savings for more rapid return on investment and a proven path to incorporating sustainability into the annual operation of commercial properties.
Discover more at https://adveco.co/products/water-heating/solar-thermal/
Building & Construction Review, is a print and digital magazine in the UK supporting more than 15,000 readers monthly. These readers include Specifiers, Facilities Managers, Directors, Senior Buyers, Project Managers, Site Managers, and individuals involved in Buildings Management.
Shortlisted by the editorial team for technical development and product innovation throughout 2022, as well as industry engagement through sales and field service support, Adveco has been recognised for its down-to-earth, practical response to the call for carbon reduction in buildings if the UK is to achieve the government’s target of net zero by 2050.
With more than 50 years of heritage in the design, supply, and servicing of robust, efficient, and cost-effective business-critical hot water systems, Adveco has risen to the challenge of helping the construction industry deliver sustainability into new commercial buildings as well as supporting the complex demands of refurbishing existing, outdated building stock.
With a proudly independent approach to innovation of sustainable hot water for commercial and public sector organisations, Adveco’s systems encompass a range of hybrid approaches that consist of heat pumps, solar thermal, direct electric water heating as well as high-efficiency gas-fired systems. All backed by a comprehensive range of hot water cylinders, ancillaries, controls, and the option for offsite construction.
“We are extremely pleased to receive this heating & ventilation award and be named one of Building & Construction Review’s companies of the year,” said Greg Brushett, UK sales manager, Adveco. “We are a tightly focused and highly competent team of application, sales and service engineers with unprecedented heritage in the commercial hot water field. We take great pride in the close working relationships we build with the specifiers, mechanical and health engineers who help create sustainable systems and the many facility and energy managers that use them. This award recognises all their hard work over the past year to help communicate the best and most cost-effective means of addressing carbon reduction across a host of varied sites with often unique demands.”
Read more in this month’s edition of Building & Construction Review
Mission Zero is an official response to the November 2020 announcement by then Prime Minister Boris Johnson of a wide-ranging plan with ten key deliverables to drive what he described as “Our green industrial revolution”. This lay the groundwork for the government’s Net Zero programme to fully decarbonise the economy by 2050 and in 2021 the Heat and Building Strategy. The plan has received criticism, not least for the lack of financial support, with major failings highlighted in subsequent independent reviews.
Now, we have the official government-commissioned review, Mission Zero is a 340-page report chaired by Conservative MP Chris Skidmore. As with previous net zero documentation, the government and review focus is skewed toward the domestic, with much focus on the decarbonisation of homes. From the get-go, we have argued that if buildings – which are responsible for as much as 40% of UK carbon emissions – are to be successfully decarbonised there needs to be a holistic approach that evenly tackles energy demand in domestic, commercial and industrial properties. Unfortunately, the review follows the line of thinking laid out in the original documentation, so is a missed opportunity.
In terms of tackling the big issue of energy supplies, the Mission Zero review calls for the introduction of a “cross-sectoral infrastructure strategy” that will focus on building and adapting energy supplies and systems to look at improving the low-carbon production of electricity, hydrogen and other liquid and gaseous fuels. This is at least an admission that more needs to be done to address the sustainability of national energy supplies. The removal of coal-fired power stations has cleansed much of the grid electricity supply, and the addition of solar and offshore wind has meant carbon budgets have so far been achieved. This grid is less ‘dirty’ and our electric carbon footprint is on par and will soon fall below that of natural gas. Electricity still has its issues, not least the cost, which is why clear direction on the production of hydrogen and other gaseous fuels, which are seen as potentially quick and cheaper to roll out through the gas grid, is so vital for meeting future energy and heating needs, especially for heavy industry and commercial properties with high energy demands, as seen in hot water generation.
The government is to make a decision by 2026 on whether the gas should be considered as part of national heat decarbonisation plans, again this focus is domestic, but early reports suggest that hydrogen is best suited to more industrial needs, at least initially. The review does call for the government to update its analysis by the end of 2023, “Of the whole system costs of the mass roll-out of hydrogen for heating, in order to ensure that the case for economic optimality and feasibility still holds.” That said, it is perhaps telling that the review which focuses so heavily on the domestic fails to mention the development of hydrogen boilers for the UK market, although it does call for hydrogen heating community trials to continue.
This continues to place focus on an electric-led path to decarbonisation, with warnings that desired rollout of heat pumps risks being undermined without investment in grid infrastructure. As such, the review urges the government and regulator Ofgem to make sure plans are in place for the longer-term secure investment in the electricity grid to deliver sufficient capacity of cheaper, low-carbon sources of energy.
The comparable costs of wholesale gas and electricity remain problematic, with the latter on average still costing 3.8 times that of gas, creating clear running cost issues for those considering moving over from gas to direct electricity as a source for heating. The review rightly exerts pressure on the government to honour previous commitments to review the existing levies on electricity as they “adversely incentivise the use of gas”. Levying policy costs and taxes on electricity bills keeps the price of electricity artificially high, which counters the message to adopt low-carbon technologies. Of course, the application of renewables in the form of heat pumps and solar thermal can greatly reduce the need for expensive direct electric water heating. Using the technology to preheat water helps offset potentially crippling running costs. But it is worth remembering that the high temperatures required for domestic hot water (DHW) reduce the efficiency of heat pumps. The cited coefficient of performance (COP) of 4 in the review for heat pumps and their stated subsequent greater efficiency than gas alternatives has to be questioned. Operating at optimum ambient conditions and in a low-temperature space heating mode such efficiency is attainable, but it is not ‘real world’, and should a system be tasked with supplying heat and hot water combined, as most domestic boilers are required to do, you are not going to achieve that level of COP. That will require more electrical energy to be input, with consequential rises in running costs. For commercial scale systems this is further exacerbated as minimum working temperatures need to reach 60°C for safe operation, heat pumps will therefore be pushed as hard as they can to deliver preheat working temperatures of 45-50°C in order to reduce carbon. But this comes at a cost so long as electricity prices remain high.
Better then to consider the application of solar thermal, a proven, robust renewable that once installed is essentially free to operate, ensuring a more rapid return on investment. When correctly installed and maintained, solar thermal will offset as much as 30% of the energy demands of a hot water system. This is where more support is required, with a replacement for the Non-Domestic Renewable Heat Incentive Scheme (NDRHI) which closed in March 2021. The review’s focus on heat pumps fails to address this situation, or the widely regarded failure of government-funded installation of heat pumps to jump-start wider adoption either domestically or across small businesses able to apply for support.
The Mission Zero review’s clear aims are to ensure a more rapid and effective strategy to move away from relying on fossil fuels for domestic heat in favour of heat pumps, to the detriment of alternatives and the wider impact of energy use in buildings outside of homes. That reflects the relative speed in which this review was conducted and published, so it is perhaps not surprising that much is skimmed over, whilst other elements feel partisan and certainly not independent.
This is most overtly communicated through the call to introduce a ban on the sale and installation of existing natural gas boilers on the market by 2033 to ensure the widespread adoption of heat pumps. Whilst this makes for good headlines and presents the review as making aggressive recommendations, as we have seen, it makes no mention of ‘hydrogen-blend’ or ‘hydrogen-ready’ appliances which are expected to circumvent such a ban, and account for almost all gas boilers and water heaters currently being sold, let alone ten years from now. On a commercial/industrial scale, high energy users will have to be exempt, simply due to the comparable electrical demands which would be needed for replacement and the punishing operational costs that would come with it. A ban would also effectively lead to the closure of gas-grid connections. The gas grid is both a relatively modern system of national energy deployment and the core, existing storage facility for future hydrogen production. The cost of closing and then reopening gas connections should hydrogen become a major tool in delivering net zero through the 2040s would be immense and counter-productive to the rapid and low-cost rollout imagined.
For commercial organisations seeking insight into the options for attaining net zero, the Mission Zero review unfortunately provides little impetus to generate greater support for the sector at a government level. The continued focus on domestic property is another missed opportunity to address the wider criticisms of how achieving net zero is to be realistically achieved.
If you are actively looking for approaches to introduce or increase the sustainability of your property, as well as controlling operational costs from energy consumption, addressing hot water demands is a good place to start. At Adveco we can provide accurate monitoring, correctly sized applications and provide a wealth of technology options from high-efficiency gas replacement through to heat pumps, solar thermal and electric water heating which can be optimised to your property’s specific daily needs.
The ‘Mission Zero’ review of net zero policy is available here.
Welcome to the New Year, read the Adveco January 2023 newsletter where we look at the trends for DHW in commercial properties, off-site constructions and meet Vince Ng.
Hot water specialist Adveco announces the appointment of Vince Ng as business development manager driving national sales accounts and Adveco’s continuing professional development (CPD) programme.
Vince will support Adveco’s portfolio of national accounts, including key brands across retail, hotels, restaurant chains and the public sector. Driven by government mandate and the increasing desire to decarbonise operations as part of a wider corporate policy that embraces the advantages of net zero for staff and customers, organisations can use the specialist knowledge Adveco can provide to address energy demands for business-critical hot water supply.
“Whether building brand new facilities or refurbishing existing buildings, Adveco’s application design services, specialist product portfolio and service contracts can help national organisations to control capital and operational expenses,” said Vince Ng, business development manager. “Critically by working in partnership with us customers operating UK-wide can reduce global warming carbon and harmful NOₓ emissions from their hot water (DHW) systems.”
A guaranteed supply of DHW is typically a more complex provision for commercial projects, often requiring bespoke applications that leverage a hybrid technological approach to achieve the necessary quantities and temperatures demanded. To help understand this, Adveco offers a range of CPDs and hands-on training for consultants, specifiers, engineers, installers and energy managers.
Adveco’s existing CPDs already cover sizing domestic hot water systems and maximising contributions from solar thermal. These are now joined by a new CPD, Best Practices for Electric-Based Commercial Hot Water Systems.
As organisations look to alternatives for securing low-carbon hot water this CPD session considers the options of achieving net zero in buildings by cutting carbon emissions through the electrification of water heating. It covers the specification of electric water heating, direct electric and low carbon methods including solar thermal and, in particular, air source heat pumps. This will provide an understanding of the challenges and issues surrounding commercial electric water heating and the importance of pairing kW to litres when designing a system and provide a clear overview of the next stage in the technological development of heat pumps.
“As a provider of hot water technologies, Adveco is proud to have a commitment towards the continued growth of knowledge and experience of professionals in the energy and sustainability sector. All our CPDs, including Best Practices for Electric-based Commercial Hot Water Systems, can be booked now with the training team as face-to-face or remote sessions,” said Vince.
Adveco is accredited with CIBSE for the provision of CPD seminars designed to contribute towards an individual’s professional development.
Hydrogen Needs More Government Support
For net zero to be successful in the UK many feel hydrogen needs more government support. Hydrogen is perceived as the simplest, fastest and most cost-effective method for reducing carbon emissions from UK building stock prior to the 2050 net zero deadline. While the focus on heat pumps (ASHP) has captured the headlines as a sustainable alternative to fossil fuels they currently have their limitations in terms of delivering effective heating in legacy structures and high-temperature hot water required for commercial applications. Work continues at pace to improve the seasonal coefficient of performance (SCOP) and water temperatures required to meet commercial building standards on construction projects, but it is recognised across the industry that heat pumps alone cannot service all commercial low-carbon demands at a meaningful installation and operational price. Therefore many, especially those dealing with property refurbishment, are looking to hydrogen to fill the deficit.
Despite the calls for action, the government has not as yet made any firm commitments beyond the initial investment in research to understand the potentiality of hydrogen as an alternative to natural gas supplies.
Now, UK ministers have offered up a plan for considering all new domestic boilers be ‘hydrogen-ready’ from 2026. The Department for Business, Energy and Industrial Strategy (BEIS) has made a statement announcing with BEIS says such a strategy will reduce replacement costs but cautions there is no guarantee homes will ultimately run on the gas. The announcement also does not offer clarity on the types of boilers, but the expectation is that the ministerial consultation will focus on 100% hydrogen-ready boilers. These appliances are supplied as standard condensing natural gas boilers that can be easily refitted with a hydrogen-compliant burner in the future when 100% hydrogen supplies become available through the gas grid.
This follows the announcement of a ban on gas boilers in new homes that comes into force in 2025, although uncertainty remains over the timeframe for the phase-out of fossil gas in existing homes. A commercial ban on boilers in new builds is still set to come into play in 2035, which better aligns with the initial rollout of hydrogen services, with a blend of just 20%. Most early recipients of hydrogen blend are expected to be heavy industrial users and potentially the commercial space. Hence BEIS’ careful response about whether homes would even benefit from the installation of hydrogen-ready boilers, especially in the period from 2026 to 2040.
The consultation, which closes in late March, argues that the strategy will reduce ‘the costs associated with scrapping natural gas-only boilers before the end of their useful life. Mandating hydrogen-ready boilers will give the industry the confidence to prepare supply chains to ensure the benefits of the potential transition are maximised,” officials said.
Hydrogen needs more government support if it is expected to play a significant role in the decarbonisation of heavy industry and the transport network. But opinion remains split on the practicality of using it in Britain’s gas network and the resulting cost to households and businesses. The consultation is aimed at also delivering confidence that consumers will not face a premium for their purchase of hydrogen-ready boilers.
Adveco remains a strong proponent for replacing natural gas with hydrogen blends and then finally a truly green 100% hydrogen supply at a national level. Considerable technical and capital investment will be required to transform existing infrastructure, which we do not see occurring in the short term. With full ministerial support and investment, hydrogen would form a considerable portion of the technical delivery of net zero during the 2040s in advance of the 2050 deadline. Instigation of early bans on gas-fired boilers is likely to be counterproductive unless purchase costs remain on par with current appliances as we firmly believe most units purchased through the mid-2020s will never see conversion to hydrogen use, especially domestically. Better to commit to 20% blend projects and clarify that the current generation of gas appliances whether domestic or commercial must show the capability to burn the blended gas. Most, such as Adveco’s AD and MD ranges, already can without requiring any form of burner adaptation. This also has the advantage of countering claims of triallists being used as ‘lab rats’ for hydrogen rollout. The announcement of ministerial consideration may start to redress the lack of investment in the technology, as we have noted hydrogen needs more government support, but once again the focus is being placed on voter-friendly domestic responses, rather than addressing the considerable issue of carbon emissions from commercial buildings where arguably organisations are better positioned to make a difference starting today.
Read more about our hydrogen future here
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.
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.
Read the Adveco December 2022 newsletter featuring Build2Perform, best practices in electric water heating, solar thermal and guidance on maintenance and servicing…
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.
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.
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.
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.