Congratulations to B&NES Council in helping all 78 state schools in the area reduce their gas consumption by a total of 18% last winter. Although much of this reduction came from the mild winter, a significant proportion was as a result of project work carried out over the course of the last year with involvement from Transition Bath.
The work started with professional energy surveys of 71 schools carried out by local energy consultancy Verco between January 2013 and April 2013. A follow-on project involving 34 schools had their heating controls adjusted and training given to their caretakers in how to better manage their boiler rooms. This has led to a 23% reduction in consumption last winter (2013/2014), adjusting this figure for the mild winter, the real impact is about a 6% reduction in consumption. Gas consumption at the 34 schools reduced from 9,000,000 kWh (£250K) to 7,400,000 kWh (£210K) saving the schools £40k. Although £40K might not seem much, if it was maintained for the next 10 years it would result in a £400,000 saving.
These 18% reductions are significantly better than that of the 12% reduction from homes in the UK this year as a result of the mild winter.
Transition Bath has been working with schools for 4 years to help them reduce their energy consumption. The rest of this article provides more information on the background to the project and more recent findings on how schools can be helped to reduce their gas consumption. We will write a subsequent article at a later date outlining similar opportunities for the reduction in electricity consumption.
Background & History of Project
2010: DECC Releases Public Building Data
4 years ago DECC released energy consumption data for public buildings data via CSE which sparked interest at Transition Bath. We looked at the data for Bath and noticed there was quite a large difference in gas consumption data between the 78 schools in Bath. It ranged from 40 kWh/m2 to 300 kWh/m2; illustrated below by the histogram:
Our initial question was, how could one school consume 40 kWh/m2/year while another 300 kWh/m2/year – 7.5 times more? These figures compare with an average of 110 kWh/m2/year consumption across all schools in the South West of England; the distribution of consumption patterns in B&NES also seems consistent with schools nationally.
The most obvious explanation was that the difference might be down to school ‘fabric’ i.e. solid walled, single glazed Victorian schools required a lot more heating than more recently built schools with insulated cavity walls and double glazing.
Plotting the construction date of the school, versus this gas consumption per floor area (kWh/m2/year) suggests this is not the case:
Each of the blue dots represents a single school, the blue line is the trend line plotted through the blue dots and the red line is the theoretical gas consumption you might expect given a school with fabric based on its age of construction.
The fact that the blue trend line is horizontal indicates that in Bath & North East Somerset there is no apparent correlation between the quality of a schools fabric from an insulation perspective and its actual gas consumption.
We felt that this discrepancy required further investigation.
2011-2012: Investigating individual schools
As a result of this information we set up a project to try and understand the reasons for these differences. This resulted in Transition Bath providing a number of energy surveys to local schools and subsequently working with them to try to reduce demand. We were helped by B&NES’s foresight to install ‘Smart Meters’ in many of the schools; these ‘Automatic Meter Reading’ (AMR) meters provided us with half hourly gas readings over a period of a number of years and was very helpful in diagnosing problems with the control of school boilers.
It transpired from this data that an average 41% of gas consumption was out of school hours:
Based on experience from the schools we provided energy surveys to there were a number of issues:
- Boilers left on at weekends and holidays – generally as a result of mis-programmed controllers
- Boilers starting too early in the morning largely because of poorly located thermostats
DECC LEAF funded project with BWCE
Subsequent to this Transition Bath was involved in a DECC LEAF funded project to look in more detail at 5 schools to see whether capital investment could be paid for in energy savings. The conclusion of the project was that although there were opportunities for savings to be made because of the relatively small size of some of the primary schools and the complexity of ownership patterns in schools (Diocesan, B&NES, Academies) an investment was going to be difficult.
2012-2014: B&NES employ a schools energy officer and 71 schools get professional energy surveys
In May 2012 the council created a new post of ‘Schools Energy Officer’ and hired Amy Dartington to address the problems highlighted by the LEAF project, and to help deliver their commitment of a 30% reduction in the council’s carbon footprint as stated in the 2009-2014 Carbon Management Plan. The Schools Carbon Management Programme was created and Resource Futures was contracted to support behaviour change and the Eco-Schools programme in Schools.
In the Autumn of 2012 the council let a contract to Verco to professionally survey all the schools in B&NES. In the end 71 of 78 schools signed up to the project and over the course of the first 4 months of 2013 every school was surveyed and received an energy report.
A common theme emerged, which replicated Transition Bath’s earlier findings that there were significant opportunities to save energy in schools through:
- Improved boiler controls
- Cavity wall insulation
- Upgrading lighting to modern more efficient fluorescents
Autumn 2013: Verco fix the controls on schools boilers
Last autumn a small contract was let to Verco to go around to many of the schools and correct some of the boiler settings which were identified during the energy surveys earlier in the year. This is something that Transition Bath had been doing at a small number of schools prior to 2013.
2014: 23% reduction in energy consumption and bulk purchasing of energy saving materials
Over the winter 34 schools who had has their controls improved used 23% less gas than previous years and on a weather/temperature adjusted basis this is about 6% – which not only beneficial to the schools but good news for the environment. This is more than the reduction across the whole schools estate of 18% and a 6% weather corrected reduction. Electricity has also reduced across all schools by 2.5%, which has reversed the trend for annual increases over the last few years.
Currently B&NES is supporting schools with an energy efficient lighting replacement bulk purchase and is also investigating whether the boiler controllers at many of the schools can be replaced with something which is better tailored to the schools’ requirements.
The remainder of this article focuses on problems relating to boiler controls and how they can be resolved. Hopefully other schools from outside B&NES can learn from our experience.
Problems with boiler controls
Optimum start, early starting problems
Most school boilers are controlled by sophisticated commercial boiler controllers; for Bath schools this is most commonly the Drayton/Satchwell DC1100 controller.
One of the features of this type of control is something called ‘Optimum Start’, which automatically varies when the boiler starts each morning based on previous knowledge of how long it takes to heat up the school up given differing outside temperatures. In practise this mean on milder mornings the boiler might start at 7.00am in order to get the school up to temperature at 8.00am, and on colder mornings it might for example start earlier at 5.30am. This optimisation is designed to save energy while always getting the school up to the correct temperature by the time it opens in the morning whatever the outside temperature.
From Transition Bath’s earlier investigations at a few schools it appeared that this feature of the boiler controllers wasn’t working well, and this was confirmed as being a wider problem during Verco’s subsequent surveys of 71 schools.
The graph below, using AMR (Smart Meter) data shows gas consumption by time of day for a school where the Optimum Start feature of the boiler controller is not working well:
The boiler is starting at about 01:00am most days, 7 hours before the schools opens.
It appears that the problem is caused by poorly sited thermostats, generally in the schools’ halls. Although their siting follows the typical convention used by heating engineers (most domestic thermostats are equivalently sited in hallways), their location appears incompatible with the ‘Optimum Start’.
What seems to happen is that the heating in most poorly insulated school halls is unable on cold days to get the room up to temperature, so the boiler controller does its best by starting the boiler as early as possible. The consequence of this is that although the hall might get up to temperature exactly on time, the rest of the school, typically classrooms get up to temperature several hours early, quite often at 3.00am!
Solving this problem is quite difficult as it involves capital investment. The ideal solution is to
- insulate the school, so it takes less time to get up to temperature and loses less heat overnight
- split the heating into zones, so the hall and the classrooms are on separate circuits and therefore the heating for the classrooms starts later in the morning than the hall
Insulating and rezoning can be expensive, so a cheaper alternative is to relocate the thermostat to a classroom at the risk that the hall is a little cold in the mornings.
Weekend and holiday usage
In the previous section we dealt with some of excess gas consumption during school days in the early hours of the morning, which amounted to about 17% of Bath schools’ consumption. A further 22% of gas is consumed during weekends and holidays:
Some of this is legitimate:
- Weekend and holiday activities
- Frost protection (boiler starting up when temperature drops below 4C outside and there is a risk of frozen pipes)
However, based on more detailed investigations at individual schools it transpires that some of this consumption is less than legitimate. Holiday periods are not programmed into the boiler controller so boilers are left on throughout all holidays, the graph below shows typical weekly heating patterns of a school which doesn’t manages holiday heating and hot water well::
At no point in the year is the heating and hot water turned off during the holidays (in red), fixing this would save this example school up to 30% of its annual consumption
- Historically there might have been a weekend event for which heating was required, but this no longer happens but no one has remembered to turn the boiler off
- Heating is required for staff working over the holidays; but we would argue it is cheaper to heat a single 40 m2 classroom using electric fan heaters than leave the heating on for the whole of a 2000 m2 school
Managing weekend and holiday heating in schools is perhaps the cheapest way for them to save energy. Ensuring that holiday schedules are setup each year and providing training and access for schools to their AMR (Smart Meter) data could make a big difference. B&NES have been going through such a program with a number of schools during 2014.
Hot water issues
Hot water accounts for an average of 17% of schools’ gas consumption in Bath. Most of the hot water is heated centrally, typically off the schools main heating boilers or separate specialist gas heating. The hot water is then circulated continuously around a hot water ‘loop’ within the school, to reduce risks of legionella and to ensure hot water is immediately available at a tap when it is turned on, rather than having to travel hundreds of meters from the boiler room. Unfortunately many of the pipes circulating the hot water are poorly insulated leading to hot water systems which are typically between 10% and 50% efficient – when they should be in the 70% to 90% range.
An example of this (which is very common) is illustrated by the graph below:
The blue part of the graph is the heat loss in the system – which was particularly obvious during the school holidays when the hot water was accidently left on but the school was empty. In this example the hot water system is only perhaps 30% efficient.
The solution to this problem is to try to follow CIBSE guidelines and to move away from centrally heated, recirculating hot water systems, to simpler point of use electric heating. Although electric heating is more carbon intensive than gas, it has the advantage that inline electric water heaters can be sited within a few meters of a tap and not have to transport hot water across long lengths of poorly insulated pipework as is currently common in schools.
The problems described in this article appear to be common to all schools in the UK. Transition Bath has surveyed a number of schools outside B&NES and there is published evidence that many schools suffer from the same problems. B&NES have however taken an enlightened approach to dealing with the problem:
- They have installed AMR/Smart Meters in the majority of the schools making it much easier to diagnose problems
- They have employed a Schools Energy Officer, surveyed the majority of schools and are going ahead with a bulk-buying program to support schools in making reductions in their energy consumption
We are hoping that other local authorities and community groups can learn from this project.
Electricity consumption in schools also suffers from similar issues in that 45% of schools’ electricity consumption is out of hours. We will provide an analysis of this and how it can be addressed in a subsequent article.
If you have any questions or would like further information on Transition Bath’s Schools Energy Program – please contact us at firstname.lastname@example.org . We have much extensive documentation on other issues associated with boiler control which we would be happy to share but have omitted for brevity! We can also make spreadsheets available which automatically analyse both electricity and gas Smart Meter data on request.