With the bosses of the UK's leading energy companies telling the Energy Committee recently that bills are likely to rise significantly in the coming years (see BBC News website for more details), it seems that 'energy efficiency', 'carbon footprint' and 'energy reduction' are likely to remain buzz words for many businesses for the forseeable future!
So, we wanted to use this opporunity to discusses the ways in which Verco is aiming to help retailers reduce energy consumption by using the latest environmental technologies such as hydrocarbons and energy efficient fans and properly installing and maintaining a cabinet.
According to the Carbon Trust, the retail sector comprises about 7% of the total UK building energy consumption and emits over five million tonnes of carbon dioxide per year. It also estimates that annual savings of up to 20% across the sector are possible; and that refrigeration represents a significant and growing electrical load, currently accounting for 14% of the total electrical energy consumed in the UK. With energy prices increasing at rates not seen for decades, improving energy efficiency in retail refrigeration is therefore a good place to make cost savings and improve retailers’ carbon footprint.
In an attempt to improve the energy efficiency of refrigerated cabinets and related equipment and appear more environmentally friendly, many retailers are adopting high-performance hydrocarbons over traditional refrigerants such as R404a. In fact we estimate that a third of enquiries for its glass-door and open-chill cabinets specify hydrocarbons – a figure that has grown significantly in recent years.
Verco’s hydrocarbon of choice is BOC’s CARE 45 (R1270), a high-purity, single component substance, which is ideal for use in many industrial and commercial refrigeration applications and offers high performance without any of the issues associated with temperature glide.
The use of hydrocarbons as refrigerants not only produces zero ODP (ozone depletion) and minimal GWP (global warming), but also helps to reduce the energy consumption of the compressor and provides energy savings that are not to be ignored.
Hydrocarbon refrigerant producers claim savings of 10-15% of the compressor energy depending on application but, as Verco development director Mike Nicholls explains, users should expect between 7% and 9%. “Many hydrocarbon and compressor trials are not conducted under normal operating conditions. The reality is that not all of the cabinet energy is compressor energy, and the compressor does not run all the time. For example, a compressor operates more during a store’s opening hours than it does when the store and the cabinet’s night blinds, are closed.”
In addition, the difference in engineering costs between a cabinet running on R404a and one running on R1270 are minimal. Using Verco’s 1.25m open-chill Kingston as an example, the increased cost in engineering is approximately £100.00.
As the main characteristic of a hydrocarbon refrigerant such as R1270 is its high flammability, most of the engineering changes concentrate on reducing the possibility of ignition to ensure the safe operation of the cabinet. Electrical components (relays, switches, etc.) that are not IP67 rated therefore have to be spark proofed or placed within an enclosure to ensure they cannot ignite a potential leak. These engineering changes ensure that cabinets comply with the latest European Standard EN 378:2008 (Refrigerating Systems & Heat Pumps - Safety and Environmental Requirements).
SO WHAT ELSE CAN BE DONE TO IMPROVE ENERGY EFFICIENCY?
Looking beyond the refrigerant and focusing on the technology available to retailers, savings can be achieved by fitting the latest energy efficient, electrically commutated (EC) fans, which use 60% less energy in operation compared with conventional fans and also reduce the amount of heat being transferred to the refrigerated space.
Further savings can also be achieved in a typical store environment by properly installing, locating and regularly maintaining cabinets. Combine this with using hydrocarbons and EC fans and it is possible to reduce energy consumption by more than 20%.
What’s more, retailers can also reduce their carbon footprint by buying Verco cabinets, simply because they are manufactured in the UK and can claim the lowest ‘carbon miles’ of any UK-specification cabinet.
Shelving is a key design factor in ensuring a cabinet’s performance and reliability. It plays an important role in stabilising the air curtain. Cold air is kept within the cabinet by an air curtain, which flows from the honeycomb at the top of the cabinet to the air return grille at the lower front. Without shelving the air curtain would simply collapse to the rear of the cabinet.
Although a sloping shelf can improve merchandising, it has a detrimental effect on airflow, raising shelf temperatures and in turn increasing energy consumption. Sloping shelves with acrylic shelf risers and indeed merchandise that protrude into the air curtain can further reduce cabinet performance.
When a cabinet is delivered to site, shelving should therefore be positioned to achieve optimum performance, with horizontal, evenly spaced shelves. If sloping shelves are a merchandising requirement, fitting smaller shelves that stay within the air curtain can restore some of the lost performance.
LOCATION LOCATION LOCATION
The location of refrigerated cabinets is one of the most important factors affecting energy efficiency and should be given a great deal of thought when planning the store environment. For example, and from the point of view of cabinet efficiency, the worst position is immediately opposite the store entrance, which exposes the cabinet to drafts, dust and litter, fluctuations in temperature and humidity, and radiant heat.
Open-chill cabinets are particularly vulnerable to drafts. The EU standard specifies that cabinets are subject to a cross draft of between 0.1 to 0.2m/sec (i.e. 1m of air movement in 6.6sec). This is obviously very low and means that if a draft can be felt in the region of a cabinet, it is too much!
Cabinets are typically tested in ISO 3 conditions, which defines the maximum ambient temperature near the top of the cabinet as 25°C. A lower ambient temperature will result in lower shelf temperatures and therefore lower running costs. Conversely an increase in ambient temperature will result in higher temperatures and increased running costs.
High ambient air humidity is also a hidden load on the cooling system because any moisture entering the cabinet will initially condense as water before forming frost on the cooling coil. The energy used in forming the condensate is therefore no longer available for cooling the display. ISO 3 conditions specify that the ambient air humidity should be a maximum of 60%.
Unlike many glass-door cabinets that are fitted with UV-resistant glass, radiant heat from the sun and other light sources such as spotlights, passes unhindered through the air curtain of an open-chill cabinet and impacts directly on the merchandise. Cabinets should therefore be sited away from direct sunlight and where possible, in environments that do not use spotlights.
Regular servicing and maintenance is essential to maintain optimum operating efficiencies and ensure long-term reliability.
A condenser obstructed by dirt and litter has to work much harder to remove heat from the cabinet, which means it is uses more electricity. Frequent cleaning of the condenser – which is normally located just behind the grille at the base of a cabinet – can easily be carried out by the end-user and is important to ensure it is free from obstruction and working efficiently.
With properly managed maintenance a cabinet should give excellent service for years. In fact, Verco has recently exchanged two cabinets that are over 25 years old and still in good working order.
Verco also offers an optional one-year labour warranty, which is available on all open-chill and glass-door cabinets in the Verco range including the new-generation Cambridge and recently launched Inline Merchandiser.
The optional labour warranty, which is being offered for a nominal charge, has been introduced in addition to the company’s existing parts cover to offer peace of mind to our customers in the event of a breakdown.