Spending more to save even more
Saving money at the start of a project by trimming the BMS specification will condemn a building to long-term higher energy bills, explains David Smithson of Siemens Building Technologies Division.
When faced with tight budgets, there can be a temptation to scrutinise the initial capital expenditure required to install an effective building energy management system (BEMS). This may mean some of its features that are crucial for ensuring optimum efficiency are removed simply to reduce the capital outlay. This short-term approach may save some costs at the start of a project, but may prove to be a false economy.
Instead, it is essential to consider the lifecycle cost benefits provided by a BEMS operating at full efficiency levels when specifying a system. This will ensure the end user receives an ongoing tangible payback,
Getting the specification right is the essential first step for an effective long-term BEMS. This will save time and money. When a BEMS is specified, it must meet the current needs of a site, and be flexible enough to provide a foundation for ongoing development or changes to the building. For example, the hiring of new staff may mean a previously empty office in a building is suddenly required and therefore requires efficient heating and lighting. Alternatively, a change in operations could see a room left empty, so it is crucial energy is not wasted unnecessarily through heating or lighting this empty space.
However, to keep upfront costs down some installers may not include certain elements of a BEMS in the initial specification. For example, one area that can be overlooked is room-occupancy sensors, which ensure the system’s heating and/or lighting settings are adjusted to the specific requirements of their environment. This means savings are achieved due to demand-based control as empty rooms are not heated or lit unnecessarily. Not including these sensors in a BEMS can really impact potential energy savings. For example, BEMS from Siemens are capable of achieving the highest energy efficiency level of the BS EN 15232 standard, but removing elements such as room occupancy sensors can mean this level is significantly reduced.
Complete integration of the technologies within a system is also crucial for achieving long-term efficiencies. By fully integrating lighting and heating, ventilation and air-conditioning (HVAC) systems within a BEMS and using room-occupancy sensors to ensure the levels of heat and light suit the specific requirements of the environment, significant savings can be achieved. For example, if there is a lot of natural light in an occupied room, the lighting system should be controlled to dim as required. In addition, sophisticated HVAC systems incorporating automatic opening and closing of vents to exploit natural cool air from outside can help control the temperature in a room without the need for air conditioning. Open communication protocols including BACnet and KNX enable these technologies to be fully integrated through a BEMS.
Once a BEMS has been specified to the highest efficiency levels, it is crucial users are fully trained on how to use it and how to ensure it continues to perform at optimum efficiency for the long-term. Users who fully understand their system and how to interact with it effectively can help ensure it performs to its best.
Making the energy use of a building visible to all staff and visitors can help drive further savings and build on efficiencies delivered by an effective BEMS. The Green Building Monitor from Siemens provides a visible presentation of a site’s energy consumption and can be displayed in reception areas to make everyone aware of the site’s performance compared to targets. Engaging building users in this way can encourage energy-saving behaviour to increase savings across an organisation.
As with most capital expenditure, the specification and installation of a BEMS needs to be viewed as a long-term purchase. By ensuring the highest levels of functionality, flexibility and performance, building users can be sure to benefit from a long-term solution — achieving energy savings and providing a superior environment for staff and visitors.
David Smithson is business unit head, UK & Ireland, for control products and systems within the Siemens Building Technologies division.