The wellbeing and environmental effects of agile working

September 22, 2020 by 2 Comments

by David Bleicher, BSRIA Publications Manager

How many times in the last few months have you started a sentence with “When things get back to normal…”? For those of us whose work mostly involves tapping keys on a keyboard, “normal” implies commuting to an office building five days a week and staying there for eight or more hours a day.

When lockdown restrictions were imposed, things that were previously unthinkable, such as working from home every day, conducting all our meetings by video call, and not having easy access to a printer, became “the new normal”.

One thing the pandemic has taught us is that changes to our work habits are possible – we don’t have to do things the way we’ve always done them. Since lockdown, agile working has been high on companies’ agendas; but agile working has a broader scope than flexible working. It is defined as “bringing people, processes, connectivity and technology, time and place together to find the most appropriate and effective way of working to carry out a particular task.”

Working from home with a cat

The triple bottom line

Agile working is indeed about much more than changing people’s working hours and locations. It’s about how people work – becoming focused on the outcome rather than the process. It’s about making the best use of technology to achieve those outcomes and it’s also about reconfiguring workplaces to better suit the new ways of working. But, when considering these outcomes, we should be looking further than the financial bottom line. The term triple bottom line is a framework that also brings social and environmental aspects into consideration.

How, when and where people work has a major impact on their wellbeing. The past few months have served as an unintentional experiment in the wellbeing effects of mass home working. Some people are less stressed and more productive working from home, providing they have regular contact with their colleagues. Other people – particularly those who don’t have a dedicated home working space – returned to their offices as soon as it was safe to do so. It depends on the individual’s preferences, personal circumstances and the nature of the work they do.

On the face of it, it would seem that increased working from home or from local coworking spaces would be a win-win for the environment. Less commuting means fewer CO2 emissions and less urban air pollution. But a study by global consulting firm and BSRIA member, WSP, found that year-round home working could result in an overall increase in CO2 emissions.

In short, it reduces office air conditioning energy use in the summer, but greatly increases home heating energy use in the winter – more than offsetting carbon savings from reduced commuting. Perhaps what this highlights most is just how inefficient the UK’s housing stock is. If we all lived in low energy homes with good level insulation and electric heat pumps, the equation would be very different. Perhaps a flexible solution allowing home working in summer and promoting office working in winter would be best from an environmental perspective.

A possible long-term effect of increased home working is that some people may move further away from their offices. For example, someone might choose to swap a five-days-a-week 20 km commute for a one-day-a-week 100 km commute. If that is also a move to a more suburban or rural location with more scattered development, less public transport and fewer amenities within walking distance, then (for that individual at least) there’ll be an increased carbon footprint. Not very agile.

Impact of technology

There’s another aspect that may not yet come high up in public awareness. Remote working is dependent on technology – in particular, the video calls that so many of us have become adept at over the past few months. All this processing burns up energy. The effect on home and office electricity bills may be negligible because the processing is done in the cloud. This isn’t some imaginary, nebulous place. The cloud is really a network of data centres around the world, churning data at lightning speed and, despite ongoing efforts, still generating a whole lot of CO2 emissions in the process. Videoconferencing definitely makes sense from both an economic and environmental perspective when it reduces the need for business travel, but if those people would “normally” be working in the same building, isn’t it just adding to global CO2 emissions?

We don’t yet know what “the new normal” is going to look like. Undoubtedly, we’re going to see more remote working, but responsible employers should weigh up the pros and cons economically, environmentally and socially. Terminating the lease on an office building may seem like a sensible cost saving, but can a workforce really be productive when they never meet face-to-face? Does an activity that seemingly reduces CO2 emissions actually just increase emissions elsewhere? Any agile working solution must take all of these things into account, and not attempt a one-size-fits-all approach to productivity, environmental good practice and employee wellbeing.

For more information on how BSRIA can support your business with energy advice and related services, visit us here: BSRIA Energy Advice.

Filed under BPE, BSRIA, building energy management systems, Building Performance Evaluation, Building services, carbon dioxide, Climate Change, covid-19, Electricity, Energy, energy consumption, energy management, energy perfomance, energy-efficiency, Environment, environmental, global warming, Heating, human comfort, offices, wellbeing, work culture, Workforce Tagged with , , , , , , , , , , , ,

What makes a good PICV?

September 22, 2020 by Leave a comment

by Andrew Pender, National Sales Manager at FloControl Ltd.

Over the last 5 years, PICVs have been widely accepted as the best method of terminal control in variable flow systems due to their energy saving potential.  The surge in popularity has led to an influx of products with varying designs, features and functionality.  This article reviews some of the mechanical PICV design elements and how they can impact on the PICV’s performance in an applicational context.

Where do we start?

To help specifiers and project engineers assess which PICV is best suited for an application, the BSRIA BTS1/2019 standard has been developed to provide a consistent test method for PICV manufacturer’s products to be benchmarked against.

Manufacturers should be able to provide test results in line with this technical standard which covers:

  • measured flow vs nominal flow
  • pressure independency or flow limitation
  • control characteristics, both linear and equal percentage
  • seat leakage test

Repeatability & Accuracy are central to the tests and they are key to good temperature control and realising the full energy saving potential of a PICV installation.

An accurate PICV means the measured results will be equal or very close to the manufacturer’s published nominal flow rate each time it is measured, known as low hysteresis.

Accuracy has a positive impact on a building’s energy consumption.  “Measured over time, a 1% increase in the accuracy of a PICV can result in a reduction of around 0.5% in the building’s overall hydronic energy consumption” (FlowCon International).

Valve accuracy is driven by the design, manufacturing process and material used for the internals of the valve.

  • The design of the PICV should allow for Full Stroke Modulating Control at all flow settings without any stroke limitation.  The flow setting and temperature control components should operate independently.  Some PICV designs use the stroke of the actuator stem to set the flow rate resulting in limited stroke and control.  This can cause issues at low flow rates whereby the PICV effectively becomes on/off irrespective of actuator selection.  
  • The manufacturing process and the component materials also contribute to accuracy. For example, injection-moulded, glass-reinforced composite materials cope better with water conditions that valves can be exposed to.  They also have less material shrinkage than other materials, delivering higher accuracy than valves that use alloy components.

What else should be considered?

The importance of accuracy and repeatability are paramount when selecting a PICV however there are other factors that should be considered:

  • Wide flow rate range – including low flow rates for heating applications, ideally covered by a small number of valves.
  • Setting the flow rate – setting the PICV can influence the accuracy. There are various scales used including set points related to flow rates and percentages. PICVs with very detailed scales with small increments between set points are more difficult to set accurately, leading to higher tolerances than the BSRIA standard recommended + 10%.
  • Wide ΔP Range – low start up pressure. To operate satisfactorily, the PICV requires a minimum pressure differential to overcome the initial spring resistance within the PICV, enabling the spring to move and take control. Care should be taken to ensure the minimum pressure differential is as low as possible to maximise the energy saving potential of the system.  The maximum DP should also be considered to ensure the PICV operates effectively under part load conditions.
  • Dirt tolerance – the Valve Control Opening Area [A] on all PICVs, irrespective of the manufacturer, is identical for each flow rate. The shape of the Control Area can be different depending on the valve design. A Rectangular flow aperture is more tolerant than an Annular flow aperture. Debris will pass through the rectangular aperture more easily.
  • Removable inserts – deliver the greatest flexibility and serviceability.  Products can be easily serviced in line without disruption. This is especially of value when water quality is poor or when flow requirements change due to changes in space usage.  Inserts can also be removed during flushing.  Valve bodies can be installed with blank caps eliminating the risk of damaging or contaminating the PICV element, whilst having a full-bore flushing capacity.
  • Installation – PICVs in general have no installation restrictions however in line with BSRIA BG29/20, it is recommended that PICVs should be installed in the return branch as small bore PICVs will have a high resistance which will hinder the flushing velocity during the forward flushing of terminal units.

Making the right choice

There are many aspects for specifiers and project engineers to consider when selecting the right PICV for an application.  The BTS1/2019 standard provides an excellent benchmark, but the individual designs also need to be carefully considered.  A correctly selected PICV will ultimately lead to a more comfortable indoor climate with better control of the space heating and cooling as well as potentially reducing the pump energy consumption in a building by up to 35%.

This post was authored by Andrew Pender, National Sales Manager at FloControl Ltd. All views expressed are those of the author. If you belong to a BSRIA Member company and wish to contribute to the BSRIA Blog, please contact marketing@bsria.co.uk

Filed under air conditioning, BEMS, best practice, BSRIA, BSRIA Member Post, Building services, buildings, Cooling, Design, Engineering, Heating, human comfort, HVAC, Technology Tagged with , , , , , , , , , , , , ,

District Heating and Cooling and Heat Interface Units are still closely tied markets

July 28, 2020 by Leave a comment

Socrates Christidis
BSRIA Research Manager – Heating and Renewables

District Heating and Cooling networks have witnessed significant growth in many European countries in the last five years and this is set to continue in the coming decade. Significant European policy initiatives, such as the Green Deal, country government promotions, alongside increased public and private investment are supporting new business models such as utilities selling heat as a service and not as a commodity, which will drive the market forward.

BSRIA research indicates that the share of heat pumps and Energy-from-Waste in district heating and cooling systems is increasing. This trend is in line with the development of the concept of 5th generation heat networks. These are demand driven and low-temperature networks, using locally available low-grade waste heat (A/C, datacentres, underground stations, etc.), low temperature renewable energy in bodies of water and solar energy instead of a central energy centre. In principle, such systems favour the use of substations at building level, but no heat interface units at the dwelling level, as these are likely to be replaced by heat pumps.

Currently industrial boilers and CHPs remain the main source of heating in District Heating networks. For instance, 85% of planned heat networks in the UK, will have a CHP as the primary source of heating and 50% will have a gas boiler as a backup. The remaining 15% will use geothermal, ground source or water source heat pumps.

Thus, in the short-term Heat Interface Units (HIUs) will remain the link between the apartment and the network.

Going forward, reducing demand for heating and increasing need for hot water and cooling imply that the market will see the uptake of:

  • All-in-one units (heating or cooling and hot water)
  • Cooling units
  • Hybrid units, with integrated electric water heating
Graph showing European HIUs market growth

The main threats for HIUs market progress are the currently lack of consistent quality of installation and COVID-19.

Heat interface units have a major impact on the overall performance of a heat network and successful operation and performance both depend on correct system design and specification, followed by competent installation and maintenance. This has been problematic, with systems inadequately designed and quite often oversized. We see some signs of improvements as the industry becomes more sensitised towards good quality district heating. Documentation is improving as well as codes of practice, testing of HIUs, and further testing on site; however, under tight budgets the emphasis is often for the lowest cost, specification compliant technology. Testing the unit in a lab and then onsite is optional but critical to ensure performance.

Closing of construction sites was the main impact of the Coronavirus pandemic, including lack of cash flow, as the invoicing is done when products are delivered onsite. The industry has also witnessed a lack of new orders from April to June, with some signs of recovery observed just after. Overall, the European sales in the first 6 months of 2020 were between 15% and 30% down, depending on country, when compared to the 6 first months of 2019.

Going forwards, new construction presents a slightly positive picture. During COVID-19 there has been delays but not cancellations in planning permissions; delays as sites operate under social distancing guidelines and some delays for new investment to come through. However, governments and authorities are still eager to go ahead with programs and incentives, with renewed emphasis on the environmental agenda.

Looking at estimations for completions of flats before and after the outbreak, the recovery is likely to accelerate in 2022, and the market is unlikely to recover before. The end of financial support schemes by governments (VAT deferral, loan schemes or furlough) is likely to have a negative impact on many businesses, including contractors. Indications are, that new build and residential sales will be hit harder than commercial ones. Southern Europe is also likely to struggle more, although recession is expected across most of European countries.

Taking all this into account, BSRIA sees the numbers of heat interface units growing steadily but at a single digit compound annual growth rate of just over 4% on a Pan-European basis. The market will become more diverse and will look for more flexible options to cater for high-end, electricity-only heating, mixed-used and communal areas.

To find out more about BSRIA’s District Energy and Heat Interface unit market studies contact us at:

Filed under BSRIA, Building services, CHP, Construction, Cooling, Energy, Heating, Market intelligence, market research Tagged with , , , , , , , ,

Overheating in homes

August 4, 2015 by Leave a comment

This post was written by BSRIA's Saryu Vatal

This post was written by Saryu Vatal, Senior Consultant of BSRIA’s Sustainable Construction Group

BSRIA’s Residential Network organised an event on the 22nd of July focussing on the issue of overheating in homes with an excellent line up of speakers. Nicola O’Connor started the day summarising an extensive research project by the Zero Carbon Hub that brought together input from government, industry and academic experts to understand the challenges around tackling the risk of overheating in homes (http://www.zerocarbonhub.org/current-projects/tackling-overheating-buildings). Chris Yates from Johnson and Starley made an appraisal of the assumptions and requirements within the Building Regulations and associated guidance as well as the implications for mechanical ventilation system manufacturers. Neil Witney from DECC explained the challenges around defining and regulating of overheating within homes, current policies and mechanisms that may be introduced in the future in response to the growing body of evidence highlighting the issue. Paul Ciniglio from First Wessex shared the organisation’s findings from several research projects and experience from their own developments, which resonated with issues highlighted by members of the audience. Bill Gething of Sustainability + Architecture and professor at the University of West England brought into perspective how changes in the way homes have been designed and built over the recent years has led to a shift in the performance of homes. James Ford, partner at Hoare Lea discussed some key considerations for designers to address the issue at early stages, to help minimise risk and dependence on active cooling solutions.

Extent of overheating

Evidence indicates that up to 20% of homes in England may already be overheating. Areas where additional risks have been highlighted include:

  • Common areas in apartment blocks, especially where community heating is installed – these areas are not assessed using SAP as they are outside the dwelling envelope. In reality, being unoccupied spaces these are often not modelled for their thermal performance (and energy use) at all. Community heating is being incorporated in an increasing number of projects and the supply network remains live even in the summer to meet the domestic hot water demand. Ensuring that the specification and installation of insulation for the distribution pipework is adequate is becoming increasingly important as buildings are made more airtight. Often stairwells and circulation areas have a high proportion of glazing and, with recent improvements in the general standard of construction and materials, tend to retain a large proportion of the heat gains. It is now important to incorporate a ventilation strategy for these spaces so that the accumulated heat can escape.
  • Urban areas – the average temperatures in city centres can be more than 4°C higher than rural areas. Flats are more common to city centres and these are often close to sources of noise and air pollution and have limited, if any, potential for cross ventilation. All these factors can combine to limit the effectiveness of natural ventilation in addressing the build-up of heat and not just in the summer. Building designs that incorporate large proportions of glazing in their facades, such as penthouses, if not carefully designed, can require air change rates that are unrealistic to achieve, using natural or mechanical ventilation systems.

Need for a definition

A number of sources and definitions are being referred to currently when evaluating for the risk of overheating in homes. These include CIBSE’s Environmental Design Guide A (2006) which sets standards for comfort, although it is not mandatory to use this to demonstrate compliance with the Building Regulations. Dynamic modelling through tools such as TAS and IES offer the opportunity of making a more comprehensive evaluation than SAP, but this option is skill, time and cost intensive. Building Regulations do not relate to limiting overheating for thermal comfort, just limiting the use of fuel and power for air-conditioning. The minimum evaluation for demonstrating compliance with Criterion 3 of Approved Document Part L of the Building Regulations needs to be carried out using SAP. While SAP is not intended to be a design tool, it is accepted that it is the default tool the industry uses widely.

Research projects have highlighted that dwellings can demonstrate a risk of overheating when evaluated against the CIBSE standard but not when modelled in SAP. Surveys from the Zero Carbon Hub study showed that nearly 60% of the housing providers surveyed had checks in place to assess the risk of overheating. However, only 30% of these housing providers explicitly included the requirement for considering the risk of overheating as part of their employees’ requirements to architects and designers. This suggests a missed opportunity for the issue to be addressed early on in the process, when cost and energy efficient measures may be effectively incorporated.

There are several challenges around the definition of conditions under which overheating can be said to occur as several factors contribute to this, including but not limited to air and radiant temperatures, humidity, air velocity, level of activity the adaptability of the individual. There are several checks that can be built into the design process which can help identify the risk at an early stage and allow for a method for mitigating these to be set up and followed through.

Contributing factors
The energy efficiency of homes in the UK has improved significantly in terms of reduction of space heating loads. This has come about in new homes through Approved Document Part L 1A of the Building Regulations and in existing homes through schemes such as the Green Deal. Homes are now less leaky and better insulated to keep warmth in but attention and emphasis is needed on measures to facilitate the expelling excess heat adequately when temperatures rise.

Homes are expected to provide comfortable conditions for occupants all year round and through a range of different occupancy patterns, which may in reality be considerably different to the standard assumptions made in modelling tools like SAP. It is possible that if modelling for thermal comfort is carried out assuming worst case assumptions for occupant density, external conditions and hours of occupancy, many homes would require mechanical cooling. There are, however a number of common sense measures that can be applied to ensure the impact of key contributing factors are minimised. These include controlling solar gains from south and west facing glazing and making provisions for adequate, secure ventilation especially when thermal mass has been incorporated in the structure.
The current extent of overheating in homes must be seen in the context of the anticipated changes in climate. With external temperatures expected to rise with an increased frequency of extreme weather conditions, homes built today must be fit for purpose for warmer summers.

Mechanical cooling?
There has been a rise reported in the installation of mechanical cooling systems in homes in the UK, more noticeably so in the south. While this may be an expected feature in high end homes, the cost of running these systems can be prohibitive, or at least perceived as so, for households where minimising expenditure on energy and fuel is a priority.
There is potential to develop low carbon mechanical cooling systems such as reversible heat pumps. The large scale uptake of these can however have some serious implications for energy supply and the capacity of the grid to accommodate a draw in peak summer months.

Way forward
In addition to affecting comfort, exposure to high temperatures over prolonged periods can have a significant impact on the health and well-being of residents. It is critical therefore to agree on a set of parameters that can help define overheating in homes and this should be carried out with input from bodies such as Public Health England.
Until a definition and modelling strategy is developed, designers and housing providers can refer to several good practice guides and research studies that help embed a common sense approach to design. There is significant potential to mitigate the risk of overheating in homes if early stage design decisions are taken with due consideration for the issue. The limitations of mechanical ventilation systems to help achieve comfort in homes must be acknowledged so that the final burden of an ill-considered design does not rest with the occupants.

References and further reading
http://www.zerocarbonhub.org/sites/default/files/resources/reports/ZCH-OverheatingInHomes-TheBigPicture-01.1.pdf
Design for Climate Change, Bill Gething and Katie Puckett, RIBA Publishing Feb 2013
http://www.arcc-network.org.uk/wordpress/wp-content/D4FC/01_Design-for-Future-Climate-Bill-Gething-report.pdf
http://www.zerocarbonhub.org/sites/default/files/resources/reports/Understanding_Overheating-Where_to_Start_NF44.pdf

To find out more about our Residential Network and to download the presentations from this meeting check out BSRIA’s Network pages.  To find out more about all of BSRIA’s networks contact tracey.tilbry@bsria.co.uk.

Filed under buildings, domestic, domestic ventilation, dwellings, Heating, housing, operation and maintenance, overheating, residential network Tagged with , , , , , ,

Best & Worst Practices Please!

June 23, 2014 by Leave a comment

Julia Evans, BSRIA Chief Executive

Julia Evans, BSRIA Chief Executive

BSRIA recently held a workshop on behalf of DECC identifying priorities to promote low carbon heating and cooling in non-domestic buildings as part of the development of its low carbon heat strategy.  Attendees were drawn from both the Young Engineers and Energy and Sustainability BSRIA networks.  Personal thanks to AECOM’s Ant Wilson for chairing the event.

It was a busy day.  It recognised that both new and existing buildings have a pivotal role in reducing greenhouse gas emissions, and by 2050 one of the key requirements will continue to be how we provide heating and cooling.

BSRIA’s Peter Tse and Ian Orme both gave excellent presentations which drew on both good and poor practices identified from more than 50 independently assessed case studies.  These, I felt, answered the questions “what does good practice look like”, as well as “what are the consequences when its not followed”.

The workshop session resulted in many suggestions as to priorities for the future.  There were a couple which caught my eye.

In response to the suggestion that one of the priorities for DECC should be identifying independently assessed best practice and developing exemplars of new technologies, a number of delegates felt that instances of “bad practice” were even more helpful.  It seemed to me that a priority for at least a part of the audience was to know what to avoid doing.  Perhaps this reflects the industry’s receptiveness to messages about risk, and that we often learn most when we make mistakes.  The emphasis on “independent assessment” also resonated.  Many have become sceptical about instances of self-identified “best practice”, and BSRIA’s independent guidance on what works, and what does not, is there to assist the industry do things better.

Another of the workshop themes was on “skills shortages”.  After many years of recession, construction companies have euphemistically “right sized”, and this means that we have lost a lot of great talent from the industry.  Now that there are green shoots of recovery in construction, there is already talk of an exacerbated “skills gap”.  This gap makes it even more challenging for the industry to deliver buildings which meet the needs of their occupiers and where innovation is required to help tackle climate change, and meet the UK’s commitment to “zero carbon” and “very low energy” buildings. This reminded me of another of BSRIA’s strengths – training provision.

BSRIA's 2014/15 Training Brochure

BSRIA’s 2014/15 Training Brochure

Finally there was an astute observation that our recent quest for low carbon buildings has meant that we have worried less about the efficient use of energy, with the net outcome that we can end up with an EPC A rating for carbon design, but a DEC G rating for energy in use.  The move to policies that move us to buildings which are both zero carbon and nearly zero energy use will hopefully remedy this, although I suspect this particular journey may contain further unintended consequences before we reach that goal.

The workshop identified many requirements if we are to create environmentally conscious buildings that meet user needs, and importantly maintain these elements over the life of the building.

BSRIA’s mission remains to “make buildings better”.  As part of my role, I’m listening to our members and the industry what they expect from BSRIA.  I’d like to extend this offer to you, so if you have ideas about BSRIA’s future role, please send them to me: Julia.evans@bsria.co.uk.

To learn more about the BSRIA workshop you can download all the presentations from our website. 

Filed under best practice, BSRIA, Building services, buildings, Construction, Cooling, Customer Satisfaction, DECC, DECs, Heating, low carbon, non-domestic, Occupant Satisfaction, skills, training Tagged with , , , , , , , , , ,

The hidden menace of corrosion in heating and cooling systems

February 21, 2014 by 1 Comment

Written by Reginald Brown, Senior Consultant at BSRIA

Written by Reginald Brown, Senior Consultant at BSRIA

Most buildings services engineers will have come across a heating or cooling system that has not received water treatment and still appears to function perfectly and another that has apparently been treated but experienced serious corrosion related failures. Why should one be vulnerable and the other not? The answer is that most common metals are subject to corrosion but the rate of corrosion and risk of failure depends on a variety of factors including the chemical and microbiological environment, temperature, flow rate and not least the thickness of the metal.

In many respects water is the ideal heat transfer medium for building services. It has a reasonably high specific heat, is liquid over a convenient temperature range and is non-flammable, non-toxic and freely available. The downside is that water is an electrolyte that facilitates corrosion in metallic pipework and components. One might think that the obvious solution is to use plastic pipework but this can actually increase the risk of corrosion of the corrodible components that remain.In a steel pipework system, the dissolved oxygen in the system water will rapidly be used up as it reacts with the large area of corrodible surface but the loss of metal thickness should be insignificant. In a plastic pipework system there are few corrodible components so oxygen concentration will remain higher for longer and the corrodible materials will continue to corrode at a high rate. This means that almost all water based heating and cooling systems should have some form of water treatment to control corrosion, and it may be even more important in plastic pipework systems.

The usual construction programme for large building projects involves installation and pressure testing of pipework followed by pre-commission cleaning and commissioning several months later. During the gap between pressure testing and pre-commission cleaning the system may be both stagnant and still contaminated with manufacturing and construction residues. This is an ideal environment for the development of biofilm and corrosion.

In traditional steel pipe systems (using BS 1387:1985 or BS EN 10255:2004 medium or heavy grade pipe) this is not too much of a problem. The relatively thick pipe (at least 3.2 mm for 1 inch nominal bore and larger) can tolerate the initial corrosion due to the oxygen in the fill water and biofilm development during subsequent stagnation conditions. Provided the pre-commissioning cleaning is carried out effectively, ideally with a biocide wash prior to chemical cleaning, there should be minimal impact on the lifetime of the system.

Thin wall steel pipes and steel panel radiators may not be so fortunate. The thickness of 25 mm nominal bore thin wall carbon steel pipe is only 1.5 mm while a typical steel panel radiator is only 1.3 mm thick. If the initial corrosion was spread uniformly across the metal surface it would not be problem but what tends to happen is that small patches of the surface become anodic relative to their surroundings and are preferentially corroded leading to rapid localised pitting. If dissolved oxygen levels persist or are replenished due air ingress, continuing additions of fresh water or permeation through non-metallic materials then the pitting can progress to perforation. Components that should last 25 years can be perforated in a few months. This is one of the most frequent types of corrosion failure reported to BSRIA and can result in expensive remedial works even before the building is occupied.

Water treatment chemicals work by inhibiting the corrosion process, either by coating the surface of the metal (anodic inhibitors) or otherwise blocking the corrosion reactions (cathodic inhibitors). However, inhibitors are not the solution to poor closed system design or operational deficiencies and certainly won’t work to best effect in a dirty system i.e. one with a high level of suspended solids and/or biological contamination. Also, the system operation must allow the inhibitors and other water treatment chemical to be maintained at an effective concentration and circulated throughout the year.

In summary, the factors necessary to avoid pitting corrosion of steel components in closed systems are:

  1. Minimise the delay between first fill and pre-commission cleaning.
  2. Carry out effective pre-commission cleaning of the pipework system.
  3. Establish, monitor and maintain effective water treatment and water quality as soon as possible in the life of the system.
  4. Circulate water throughout the system on a daily basis to avoid stagnation.
  5. Avoid ingress of oxygen from inadequate pressurisation or excessive fresh water additions.

What happens in the first few weeks of the system can prevent pipe corrosion like this over the next 25 years

What happens in the first few weeks of the system can prevent pipe corrosion like this over the next 25 years

What happens in the first few weeks of the life of the system will influence its fate over the next 25 years. You can’t easily see what is going on inside a pipe but get it wrong and you could be looking at major remedial works in a tenth of that time.

A detailed discussion of corrosion and the use of inhibitors and other chemicals is contained in BSRIA BG50 Water Treatment for Closed Heating and Cooling Systems. Pre-commissioning cleaning is described in BSRIA BG29 Pre-commission cleaning of pipework systems. Guidance on the monitoring of water quality in closed systems is contained in these documents and BS 8552 Sampling and monitoring of water from building services closed systems – Code of practice.

BSRIA also runs a Pre-commission cleaning of pipework systems training course and provides independent failure investigations for all types of building plant and systems including pipweork corrosion.

This article was first published in Modern Building Services.

Filed under BSRIA, commissioning, Compliance, Construction, Cooling, Heating, Pipework, Pressure testing, Water treatment Tagged with , , , , , , , , , , , ,

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