This section explains what is known around here as ‘the boring bit’; it’s all about managing energy to make sure we are using it efficiently and wisely. It’s not quite as glitzy as windmills but is the best place to start; as with packaging, first see how you can reduce.
Energy is often not really considered and certainly in smaller organisations not as closely managed as other resources. In fact I would challenge anyone who spends a little time investigating their home or place of work not to find some kind of energy squandering, whether a corridor lights left on all night, or an air conditioned room with the windows open in the height of summer.
At Riverford we use some oil for heating (although hopefully not for much longer – wood chip is on the agenda) and electricity for all sorts of things. The biggest energy user is refrigeration; we have a number of cold stores of varying ages and sizes doing various jobs. Combined they are responsible for around 70% of our electricity demand, and so indirectly make up for about 7% of our carbon footprint.
appointing our own Tsar
Given the significance of refrigeration to our energy use on site we appointed a ‘fridge tsar’ responsible for day to day monitoring of the cold stores and looking into further ways to reduce energy use.
dusting: By routinely cleaning the dust off our heat exchangers (farms are dusty places) we estimate that we have reduced fridge-associated electricity use by around 10%. We also found that simply setting the thermostat lower when the store is not getting to temperature doesn’t work, it just makes everything work harder and use more energy. Adjusting the thermostats to where they were supposed to be, combined with cleaning, means our stores now stay at the right temperature and use less energy.
insulation: Once you have a system working properly, you can start to look at ways of improving it either by tweaking controls or technical improvements. One of the most obvious ports of call for us was to look at the insulation in some of our stores, which have evolved over the years from long-term potato stores to general stores accessed daily; bits have been bolted-on and shifted around as the company grew. A morning walking round with a thermal imaging camera revealed a number of weak spots in our insulation where we were simply letting in the heat from outside. This has been easily remedied and we expect it to knock at least 1% off our annual use.
shutting doors: it can be a pain but it certainly makes a difference;we have been monitoring our doors and found some of them to be open for 60% of the working day! Even with a good strip curtain this will represent a significant additional load on the cold stores. Raising staff awareness of the importance of this has improved the situation somewhat but in some cases it is simply not practical to stop what you are doing, haul the door closed, put down your pallet, open the door again, go out, close it again. Some of our newer stores have self closing doors which open just long enough to let you through and we will be looking at getting more of these over the next couple of years.
technical tweaks: a couple of the older stores have fans circulating air in them 24/7, again a legacy of once being a long term store where this would have prevented decay. This is no longer needed and by tweaking the controls a little these fans will shut down when the stores are at the right temperature. This, combined with some fan speed regulation, and a couple of other little adjustments, will reduce our electricity use by around 5%.
Sometimes it’s the simple things. We direct waste heat from one of our stores into a small shed used to dry onions, thereby negating the need for separate heating and additional CO2 emissions. When there are no onions in the store we open a vent which sends the warm air into the workshops, just enough to take the chill off the air.
In the newer buildings we have an under floor heating system which uses the low grade heat reclaimed from one of our other refrigeration units. Although it produces most heat in the summer when we don’t really need it, it produces enough to keep us warm all winter. The same system is used to pre-heat boiler water for our farm restaurant, The Field Kitchen, meaning it only has to be raised by 30°C rather than say 60°C, halving the energy required.
the 'black box'
At the beginning of August we installed our biggest energy saving project to date; a voltage regulation device which we expect to reduce electricity use by 13% over the whole site. This is because of the mismatch between the design voltage of much of our equipment and the voltage with which we are supplied by the electricity board (although it is still within the legal limits within which they are required to supply).
It has always struck me as idiotic that fan motors are situated inside cold stores; devices that produce waste heat, put somewhere specifically designed to house products sensitive to ambient temperatures, let alone heat. You pay for it twice, once to run the motor and once to remove its waste heat. Running motors on too high a voltage further increases the waste heat generated by motors. With this in mind we expect to make a secondary saving when we reduce our voltage.
Someone specified a smart lighting system for our new offices; it switches banks of lights on and off depending on who is in the office, it also regulates the amount of light provided depending on how much natural light there is. Someone didn’t commission it however, so for the first 10 months we were all sat in blinding light with no way of turning it off. It also stayed on for an hour after everyone went home. That wasn’t the plan. We finally got hold of the controls and now lights switch off if you don’t move around enough, and when it’s sunny we know because the lights go off. It provides a much nicer working environment and reduces our electricity use. We will look at this for our pack house which has many more skylights.