In the trenches for energy efficiency
The search for energy efficient heating and cooling solutions needn’t take us towards new technologies. Established systems such as trench heating can offer the ideal solution for projects, as David Taylor explains.
The quest for energy efficient buildings can be in direct conflict with comfortable working conditions for the occupier. Issues surrounding poor air quality, as well as disappointing returns on investments through performance gaps in renewable technologies, have on occasion disappointed the asset owner and end user alike.
At the same time boiler and chiller technologies have improved considerably and manufacturers’ published efficiencies of these products are being realised in the field. This is good news at the point of generation, however if this energy is not harnessed and controlled correctly, the benefits can be lost.
Whether traditional or modern, trench heating can be applied in a range of building types.
How systems are controlled is clearly integral to the design process, whilst selecting the appropriate heating and cooling emitters for specific applications makes a vital contribution to both efficiency and the environmental comfort of the occupier. Good air quality, comfortable ambient temperatures, low noise levels and appropriate lighting are known to enhance the performance of the people working within the building.
A major consideration when selecting heat emitters for a building must be the variable occupancy, building usage, building orientation and the possibility of having four seasons’ weather in one day, which is common in the UK climate. These considerations are of particular importance in buildings with large glazed areas, where solar gains and losses are common.
Heat emitters that respond quickly to these changes can increase the seasonal efficiency of a building substantially, reduce CO2 and NOx emissions and at the same time increase the well-being of occupants and enhance their performance.
Trench heating systems provide a highly effective, tried and tested solution for countering down draughts on cold surfaces, helping to prevent unsightly condensation on large glazed areas and outside walls. Trench heating works well in a wide variety of commercial and institutional buildings, for example, high-rise offices, car showrooms, airports, universities and exhibition centres, where extensive glazed areas are a common feature.
Natural convection heating trench systems have no moving parts and are effectively silent, making them ideal for acoustically reverberant spaces. Low temperature hot water is the most commonly used heating medium, however electric trench emitters are available for certain applications. Fan assisted trench or forced convection systems are a compact alternative when higher outputs are required and space is restricted. In addition, fan assisted trench emitters can incorporate a cooling coil and drip tray, typically available as either a 2-pipe or 4-pipe application, similar to fan coil units.
Natural convection units require little if any maintenance, whilst fan assisted units are, by their very nature, readily accessible for routine maintenance with no need to consider the dangers of working at heights. All electrically-powered heated trench emitters must comply fully with EN 60335-2-30 (Heaters intended to be built into floor areas and having a grille or opening at or near floor level shall be constructed so that any water spillage does not present a hazard).
Trench heating systems using low temperature hot water have inherent low water content, making them extremely efficient and responsive to the solar heating gain experienced in large glazed facades. Fan-assisted trench units with cooling coils can be used to offset these solar gains still further during the summer months, again with no additional grilles or systems, other than making chilled water available.
Trench heating can provide an excellent solution to heating, cooling and ventilation in buildings with heavily glazed facades.
These systems can integrate with building management systems to meet both comfort and time schedule requirements, and on forced convection units the warm-up times can be reduced by increasing the fan speed, supporting greater efficiency. Trench heaters can be modified to integrate with a ventilation system, thus allowing primary or fresh air to be distributed with no additional floor grilles required and local tempering of the air if required.
Not requiring any wall space, yet providing an even distribution of heat along the entire length of the emitter, trench systems provide an effective, aesthetically attractive, none-intrusive heat emitter solution to the architect, engineer and client, delivering comfort in hard-to-serve areas.
Another benefit of trench heating is that modern methods of design mean that today’s systems can be standard or bespoke to the client’s required dimensions and outputs. It’s also possible to add design features such as stainless steel, anodised aluminium, cast iron or even sustainable wood finishes that match an architectural brief. Trench heating emitters can provide the perfect solution to heating, cooling and ventilation for both traditional and contemporary buildings.
David Taylor is regional sales manager at Dunham Bush