Over the past 18 months we have been working with a national care home provider who has constructed 150 new buildings over the past 10 years. Of those 150, 65 were identified as having significant heating and hot water issues, including in buildings only months old. Confused and concerned about this statistic the organisation commissioned us to investigate, make recommendations and resolve the issues found at these sites. Through our work on these sites and many others like them, we have compiled a list of 10 top tips to ensure optimum efficiency of a new-build.
1. Ensure optimal water temperature
Many new-builds will have high efficiency condensing boilers, however in order for these to operate in condensing mode the return temperature of the water from the building must be below 55°C. If the boiler is not operating in condensing mode, the high efficiencies the manufacturers suggest you should be getting will not be achieved. Many systems are only designed, commissioned or controlled to deliver condensing temperatures at peak winter temperatures. In order to deliver year-round efficiency ensure your system has been designed and commissioned so that the return water temperature is below 55°C at all times.
2. Ensure pumps are commissioned and installed correctly
If you opt for a variable speed pump, ensure the system has been designed, commissioned and installed so that you get variable speed pumping. For this to happen the system needs to detect when each space comes to temperature, at which point the system should stop the flow (not divert it), the pump therefore sees an increase in pressure and backs off. Systems shutting down in this way also has the benefit of preventing heating water from short-circuiting back to the boilers and elevating the return temperatures (which as we’ve seen above prevents condensing taking place in your boiler), this means having a two port control strategy as opposed to a three port.
3. Fill your new system with clean (treated) water
We recommend keeping oxygen, bacteria and hardness (scale) out of the water system from the very start. The industry standard is to fill, pressure test and flush new pipework systems with approximately 20 system volumes worth of water from the tap, straight into the drain. Not only is this wasteful and polluting but it also introduces oxygen, bacteria and scale to your brand new system. A build-up of any of these on heat exchanges, pumps or any other system component will mean a reduction in efficiency and potential damage to your system which, if treated correctly, should last decades.
An alternative method to the industry standard is a re-circulatory filtration system which involves filling the system from day one (before pressure testing) with treated water. Your new system can then be flushed by passing the treated water through a filtration and pumping station and back around the system. This method means no water wasted, no polluted water put into the drain and no oxygen, bacteria or scale in your system at any point.
Once your system is up and running you should ensure you clean the air and dirt separators and strainers regularly. In a new system these components should be cleaned weekly/monthly until they are no longer picking up contaminants, at which point, you can reduce the cleaning schedule to 6 monthly. If these components aren’t being cleaned regularly then the flow can be restricted and damage can be caused to the system.
Finally, in relation to water, don’t be tempted to cut costs with an aluminium boiler. The mixing of metals (i.e. an aluminium boiler with steel pipework) makes dosing the system (adding chemicals to the water to reduce oxygen and bacteria) much more difficult. The reason for this is that different metals require different pH levels to prevent corrosion. Our advice therefore is to go for steel throughout so that dosing is much easier and your system will last longer.
4. Don’t over-specify your boiler
When your system is being designed a boiler will be chosen based on peak winter conditions, a safety factor is then added followed by up to an additional 60% for heat up. At this point the specification is given to a contractor who may also top up the size of the boiler. The resulting system will be 2-3 times larger than your requirement even on a peak winter day with no one in the building. The problem with this is that boilers can only be turned down to approximately 20% of their usual output, after which they will turn on and off which is highly inefficient. Question your designer to ensure the capacity of your system has been carefully specified.
5. Consider your metering strategy
Think carefully about your metering strategy, not just for electricity meters but heat and gas meters as well. Ensure meters are installed correctly and that they are connected to your BMS (Building Energy Management System). Also ensure you collect data from day one as this will help with future energy efficiency improvement projects. If you have a communal or district heating system, ensure are you compliant with the Heat Network Metering and Billing Regulations 2014 (HNMBR). Consider the types of information you may want collect, how often you may want to collect it and for how long the data is stored.
6. Insulate thoroughly
Ensure all the difficult components of the system are insulated as well as the straightforward pipework. This includes flange and valves, air and dirt separators and strainers. Each of these, if left uninsulated, could be costing your users £20-30 a year in wasted heat, compared with an insulation jacket which could cost as little as £10. We’re not just talking about the plant room here, also consider ceiling voids.
7. Install and optimise LED lighting
Make sure you are getting a good quality LED system which retains colour throughout its life. If you have daylight dimming, ensure it is commissioned properly. We also recommend installing constant luminance controls so the system dims the lights to begin with (when typically a lamp will omit 20% more light than its specification) and then over time as the lights degrade the system increases the brightness, the result of this is constant luminance of lighting and energy savings early on. We also recommend (where appropriate for the users) absence detection as opposed to presence detection so that lights turn off when someone exits a room but do not automatically turn on if not needed.
8. Get to know your Building Energy Management System (BMS)
Although your designer may have specified a particular BMS early on in the planning process, we often see this information getting lost at some point along the way and the contractors who are responsible for installing the BMS making a decision at point of installation which may not fall in line with the designer’s original specification.
Ask your designer/contractor to explain what you’re going to get with your BMS and how it’s going to be controlled, are you wanting remote monitoring? Will you be tied into expensive maintenance contracts with the manufacturer? And crucially, make sure you end up with what was originally specified.
9. Beware of overheating plantrooms
We see this all too often and it can be down to a number of issues. Perhaps the most common is a lack of appropriate ventilation. The British standard requires both high and low level vents to allow buoyancy driven ventilation throughout the plantroom. Other factors which could contribute to overheating in the plantroom may be poorly insulated equipment or boilers running at too high a temperature. Our advice is to challenge your designer/contractor to ensure you aren’t going to have problems with an overheating plantroom, in extreme cases we’ve seen neighbouring accommodation uninhabitable which is obviously less than ideal for your business.
10. Keep a detailed operation and maintenance (O&M) manual
Having a full O&M manual is crucially important for both current maintenance and future works. We recommend this to include drawings, calculations, descriptions of how the system is meant to work, plus any commissioning data that has been carried out. It’s also beneficial to have digital copies of drawings, ideally in AutoCAD (DWG) format. And finally on the note of documentation, it’s really important to ensure that the information in the O&M manual is accessible to all, avoid heavily technical content so that staff, management and maintenance teams, current and future can understand the system and how it should operate.
Need a little more advice?
By following the above advice your new building should achieve a minimum level of efficiency and your users shouldn’t experience any issues with heating or how water supply. However, this is only the tip of the iceberg in terms of potential energy, carbon and cost reduction. For more detailed advice please get in touch and one of our expert engineers or consultants will be happy to help.