Author: Conor Clarke, head of energy conservation unit/senior engineer, mechanical and electrical section, Office of Public Works
When tasked with improving the energy efficiency of a building, most engineers instinctively turn their thoughts towards refurbishment projects. Whether it be upgrades to the building fabric, lighting or boilers, engineers are usually most comfortable where the feasibility of a project can be assessed by comparing the required capital outlay to the calculated savings.
An area that is often overlooked is the savings that can be achieved by encouraging behavioural change of the building occupants, optimising the existing control systems and eliminating energy wastage. Over the past number of years the Office of Public Works (OPW) has been targeting these savings in its portfolio of buildings.
The results have been extremely impressive (currently approximately 20 per cent energy savings per annum) with a very high return on investment (four to one). This article explores how the OPW's energy efficiency programme evolved and how substantial energy and cost savings have been achieved with limited expenditure.
Most members of the public associate the OPW with heritage buildings and flood relief schemes, however one of its main functions is property management. The OPW manages one of the largest property portfolios in the state comprising more than 2,500 buildings. Of these, there are approximately 270 large buildings (>1,000m2) providing accommodation for staff in central government departments and some state agencies.
Primarily these are office buildings but there are also laboratories, garda stations, data centres and heritage buildings. The OPW is responsible for the maintenance of the majority of the buildings, but the occupying departments pay for their own energy.
OPW actively involved in energy conservation for a long time
The OPW has been actively involved in energy conservation for a long time. Going back to the early 1990s, in conjunction with the Irish Energy Centre (now SEAI), a large-scale energy conservation campaign for staff in approximately 200 buildings was launched. An energy officer was appointed in each building. Each energy officer was provided with information on energy conservation measures that could be implemented in a typical office.
In order for a behavioural change campaign to be successful, it is necessary to provide the participants with reliable and up-to-date feedback on the results of their efforts. Energy consumption was measured from data obtained from utility bills. Although this seemed like a practical way of obtaining consumption information, it ultimately proved unsuccessful due to the large administrative burden in collecting and processing the data and the inherent historical nature of the bills.
The arrival of cost-effective Building Management Systems (BMS) in the mid-1990s presented an excellent opportunity to both remotely control and monitor heating, ventilation and air conditioning (HVAC) systems in buildings. This was an enormous advantage to the OPW with its portfolio located in diverse geographical locations throughout the country.
BMS proved to be excellent at controlling the plant in buildings, but energy data collection was more problematic. The priority at the time was also more aligned to maintenance than to energy; no one was screaming for their energy report; however, if there was no heat on a cold winter morning, that was a different matter.
Early 2000s saw emergence of dedicated Energy Monitoring Systems
The early 2000s saw the emergence of dedicated Energy Monitoring Systems (EMS). These systems typically consisted of a logging device connected to energy meters. The systems had much larger local data storage capacity than BMS and were completely tailored to energy monitoring and reporting.
A decision was made to separate the functions of control (BMS) and energy data collection (EMS). EMS were installed in each large building and typically connected to the main utility meters.
With the availability of up-to-date and reliable energy data for almost 250 buildings, in 2007 the OPW ran a pilot study to ascertain the potential energy savings in a typical office building by engaging with the staff, optimising the existing controls and eliminating energy waste. Ten buildings were chosen at random for the pilot study.
It was noted that in all the participating buildings there was very significant electrical consumption during unoccupied periods, that is, at night and at the weekends. Typically this 'out of hours' consumption was about 50 per cent, in other words approximately half of the electrical energy in the buildings was being consumed when the buildings were unoccupied. The graphs below illustrate the electrical consumption in five of the pilot study buildings during occupied and unoccupied periods. It can been seen that the breakdown for each building is very consistent.
Electrical consumption in five pilot study buildings during occupied and unoccupied periods
Staff in the buildings were able to have a direct influence on electrical consumption. The simple messages of 'switch off' and if it can’t be switched off 'turn it off as soon as possible', were the key messages for behavioural change. It was observed that there was a high base load in most buildings, that is, the electrical load that is constantly on.
Out-of-hours audits were carried out and it was found that there were substantial savings possible from switching off equipment that was running unnecessarily. Savings of up to 19 per cent were achieved in the pilot study buildings.
The positive findings from the pilot study provided a solid case for expanding the programme into all of the 250 large buildings in the portfolio. The campaign, entitled 'Optimising Power @ Work (OP@W)' was launched in 2008 and has three key fundamentals:
- Technology: energy logging equipment is installed in each building before the campaign commences. The electrical and thermal energy consumption data is recorded every 15 minutes and is stored on the OPW’s Central Energy Data Repository (CEDaR). The database is open source and can collect data from various different types of logging equipment. Once the data is collected there are different data analysis packages used to generate energy reports.
- Staff engagement: the success of the campaign in a particular building or facility is highly dependent on the level of staff participation. It is essential that the campaign is endorsed by senior management. An energy officer is appointed in each building and they become the key contact person to drive the campaign. Working with the energy officer an energy team is established in each building. The energy team is comprised of multiple stakeholders from different areas, for example, a typical energy team might have a representative from IT, from the cleaning staff (as these are usually the last out of the building), from security staff and also representatives from the various departments within the building.
- Specialist expertise: one of the key features which differentiates Optimising Power @ Work from other behavioural change campaigns is the provision of expert advice from an energy specialist who works with the energy teams in each building for the entire duration of the campaign. The energy specialist prepares regular energy reports and presents recommendations at each energy team meeting (typically monthly). The specialist will arrange for out-of-hours energy audits, Building Management System (BMS) audits, staff lectures/workshops and so on.
In the first year of OP@W the savings were relatively modest. However, as the energy teams in each building became established, the savings started to improve. By the end of the second year the average savings were 14.75 per cent. The average savings have continued to improve and the buildings are consuming approximately 20 per cent less now per annum (using the 12 months before the campaign commenced as the benchmark for comparison).
After the first two years of the campaign, each building was categorised as to the level of engagement (energy team, senior management and general staff). This was then compared to the savings being achieved in the building. The graph below illustrates the findings.
Where the level of engagement in the buildings was classed as 'Excellent', the annual savings were on average 19 per cent. The average annual savings then decreased to 12 per cent and two per cent where the engagement was deemed to be 'Good' and 'Fair' respectively. However, the most interesting observation was that in buildings that were not participating, but were being monitored, the energy consumption actually increased by 11 per cent.
The graph below shows the energy and carbon dioxide savings that have been achieved in the campaign each year to date. Although they have fluctuated from year to year, the general trend has been towards increased savings.
OPW prepares Display Energy Certificates for each building participating in Optimising Power @ Work
The OPW prepares Display Energy Certificates (DECs) for each building participating in Optimising Power @ Work. The DEC is calculated from the actual energy consumption in each building and normalised for building type, floor area and weather. The DECs are revised annually. An 'average' building will have a rating on the line between 'D' & 'E' rating.
The graph below shows the distribution of ratings for 200 buildings for the years 2013 and 2015.
It can be seen that the vast majority of buildings are better than the average i.e. 'D2' or better. It is also noted that there are a greater number of buildings rated above average in 2015 compared with 2013, showing that there has been a continual improvement in the operational energy performance.
The success of the Optimising Power @ Work campaign in central government buildings was noted by both the Department of Public Expenditure and Reform (DPER) and the Department of Communications, Energy and Natural Resources (DCENR) and this led to a government decision in 2013 to expand the programme into the wider public sector.
Although the campaign is tailored for each specific type of facility, the core principles of technology, specialist resources and staff engagement remain the same. The programme is now operating in hospitals, institutes of technology, universities, prisons and local authority HQ buildings. Initial indications are that savings will be in line with those achieved in the central government buildings.
The government's 33 per cent energy efficiency target for the public sector by 2020 is ambitious. The OPW's campaign, however, demonstrates that savings of 20 per cent are possible. It should be noted that the private sector energy efficiency target is 20 per cent.
With regard to energy efficiency, the best return on investment will be achieved through a programme of behavioural change, control optimisation and elimination of energy wastage. In terms of cost benefit these measures are an essential first step to improving energy efficiency. Capital projects should be considered secondary and the next step in any cohesive energy efficiency plan.