Energy efficiency in non-domestic buildings - our insights and experiences
Author: Date: 05/04/2016
UK non-domestic buildings account for approximately 13% of final energy consumption. Disappointingly, the Committee on Climate Change’s 2015 report illustrated the need for better energy performance and energy savings: “Non-residential buildings emissions have stayed flat, with little evidence of any energy efficiency improvement.”
The root causes
The root causes of poor energy performance in buildings originate at all stages in the build delivery cycle. Our experience shows that a structured approach is needed – such as our Assured Performance Process. This whole-system approach identifies and eliminates energy ‘performance gap’ issues at each stage from planning through to handover, highlighting risks that can’t be eliminated, for extra attention in the detailing and construction stages. This close attention to potential risks pays dividends later and helps to avoid the kind of poor operating practices we see all too often:
- Building management systems not properly commissioned or set up at handover - complex controls, poor operating instructions, inadequate labelling and systems inappropriately programmed for their occupancy.
- Inadequate training on operating the building efficiently.
- No interlock on heating and cooling systems, allowing occupants to have both running simultaneously.
- Air-conditioning that is too high capacity for the areas it serves, and installed without calculating the relevant load.
- Heating and air-conditioning systems that are set either too high or too low, instead of providing a comfortable environment for most people while allowing them to dress according to their own personal comfort.
- Air-conditioning systems that are left on in unoccupied areas when sensors would solve the problem.
- Heat rejection pipes from portable coolers poked into the ceiling void or behind furniture - as if this can magic the heat away!
- Ventilation fans that run overnight, removing heat from the building and increasing the morning re-heat load. Either fit better controls or re-configure the operating hours.
- No natural light or inappropriate lighting. Lighting is often inefficient, has zoning deficiencies or uses poor controls. It can be too dim or too light, and is all too often left permanently on. Adjusting the amount of lighting, fitting LEDs with lux levels suited to the location and use, or installing motion sensor controls are often affordable, and offer short paybacks.
- Heating on, windows open. Fit window sensors that switch the heating off automatically when they are opened.
- Poor implementation of sub-metering, made worse by no clear understanding of how to use it properly and the benefits it can provide.
- Loading bay doors that are left open unnecessarily.
- Poorly maintained refrigeration – missing doors, broken hinges and worn seals.
- Doors in shops and offices either left permanently open or open/close too frequently.
- Uninsulated hot water tanks, pipework, valves, flanges and pumps.
- Hot water overheated to combat diseases such as legionella, but without doing a realistic risk assessment.
- South-facing, highly-glazed buildings, without shading - leading to overheating and an increased requirement for cooling. Solutions include blinds, window film or brise soleil shading.
Where to start?
A building procured to suit a specific client or need enables many of these issues to be considered at the specification stage and, with the right focus, can be followed through during delivery – using an Assured Performance Approach. However, many occupants and managers are faced with an existing building, not built to their specification. Here it’s important to understand the building and how it operates, and then to work within the scope available to optimise performance in relation to the activities it hosts. Where to start?
- Review the age, condition and performance of the building fabric, plant and equipment, and controls.
- Undertake site inspections (ideally using a tool such as CIBSE TM22) to identify and prioritise improvements. They should be carried out when the building is occupied and also when it’s not; in both winter and summer; and when there’s a change in use or key equipment is replaced.
- Get feedback from the occupants using a structured survey (Building Use Survey) or a home-grown version.
Our VolDEC scheme can help. It’s an operational energy performance certification scheme based on the methodology used with mandatory Display Energy Certificates. In particular, VolDECs solve the issues around the landlord and tenant energy split. They provide property owners and operators with energy ratings for the specific areas of a building that they control or manage, and are therefore able to improve.
Initially, it’s best to focus on the low-cost opportunities, often with short paybacks. These are generally operational and can often be implemented quickly. One property owner we worked with saved at least 20% of landlord energy use through basic, low-tech measures and improved procedures.
Next are the low and medium-cost opportunities, with paybacks typically between two and five years. These often include the replacement or enhancement of controls or smaller plant and equipment.
Lastly are those opportunities with the longest paybacks, including the replacement of lighting systems and HVAC plant.
Little excuse and every opportunity
The CCC’s finding might be disappointing but, with a common sense approach and easy-to-access tools, non-domestic Energy Managers can, and should, be more aggressive in their targeting of energy improvements. Despite there being less of a push from legislation, there’s both little excuse and every opportunity for reducing energy use and costs, as well as improving efficiency, occupant comfort and staff productivity.
This piece was originally written for MBS (Modern Building Services) and is reproduced here with permission from MBS Portico Publishing Ltd