Providing effective and efficient heating for a warehouse presents a number of challenges which need to be addressed, with reference to both the nature of the building and the layout of the storage facilities within it.
Getting it wrong can result in poor heat distribution throughout the space, to the detriment of the comfort of people working in the building. It may also lead to wasting energy, thereby increasing running costs and carbon footprint. So if you want to know how to heat a warehouse, read the detailed blog on the various warehouse heating solutions.
There are essentially two options for heating warehouses – radiant heating and warm air heating. As explained below, using warm air heating (of which there are several types) is usually the most efficient option for warehouses, particularly those with high racking.
As its name suggests, a warm air heater warms the air in the space and this, in turn, warms the people working there.
To achieve this, air is drawn across a heat exchanger to increase its temperature. The warmed air is then distributed through the space by a fan. The selected heating system therefore needs to ensure that the warmed air is distributed evenly throughout the space to maintain consistent temperatures.
There are several choices of heat source for warm air heaters. These include a gas or oil fired burner located within the body of the heater (direct-fired), hot water piped to the heater from central heating plant such as a boiler (indirect-fired) or an electric element.
Modern direct-fired warm air heaters are now available in condensing versions, which operate in the same way as condensing boilers to deliver very high energy efficiency.
Warm air heaters may be suspended from the roof, mounted on a wall or they can stand on the floor.
In the case of floor-standing models it is important to be aware that they will occupy some of the floor space that could otherwise be used for other purposes. However, their positioning makes them easier to access for maintenance.
A special type of floor-standing heater, developed specifically for warehousing by Powrmatic Inc. In the USA, is air rotation heating. Air rotation heaters use large, high-efficiency axial fans to move large volumes of air through the space at relatively low temperatures. In operating with low temperatures these heaters can also make use of condensing technology to optimise energy efficiency.
Radiant heating is typically provided either by suspended radiant tubes or, less commonly, by radiant plaque heaters which may be suspended or wall-mounted.
All types of radiant heating emit infrared radiation from hot surfaces and it is this radiated heat that warms people and other objects. Radiant heating does not warm the air that it passes through.
A well-designed warm air heating system will distribute warm air throughout the space, so that there is hardly any temperature variation from one area to another. The key to ensuring this is the positioning of the warm air heaters to ensure that the warmed air is able to travel freely throughout the space so that there are no ‘cold spots’.
One of the limitations of radiant heating is that for people to be warmed by it, they need to be in ‘direct line of sight’. In a warehouse with tall structures such as racking this may prove difficult to achieve as the racking will effectively ‘shade’ people from the heat source.
However radiant heating may be suitable if there are no such tall structures. It may also be the best option for areas frequently open to outside air, such as a loading bay.
In any building with a high roof it is inevitable that some of the warmed air will rise the top of the building, potentially wasting energy. The answer is to combine warm air heating with suspended fans that re-circulate the warm air from the roof to the occupied space at floor level.
This is discussed in more detail in our blog on destratification.
Coping with dense racking
As logistics and warehousing companies seek to maximise the use of floor space there is a growing trend towards positioning racking closer together, making it more difficult to achieve effective warm air distribution from suspended, wall-mounted or floor-standing warm air heaters.
Similarly, radiant heaters would be unable to provide even heating in such circumstances.
In these situations, the solution is air rotation heating (described above) as the higher powered fans are able to move the air effectively throughout the space, including through dense racking. Also, with air rotation heating there is no need for destratification.
A further benefit of air rotation heating is that it is effective irrespective of the configuration of the space, so that any future changes in layout of the warehouse space do not necessitate changes to the heating system.
Achieving optimum energy efficiency involves both selecting efficient heating plant and controlling it effectively to ensure that no energy is wasted.
The control strategy will need to be aligned to both the layout of the space and the ways in which different areas are used.
For example, if there are some areas of the space that are used very occasionally it may be beneficial to zone the heating system so that those occasionally occupied spaces are not heated to the same temperature as areas where people are working all day.
There will also be benefits to using timed control to bring the heating on before work starts to ensure the building is warm when people arrive and turn it off at the end of the working day.
The morning pre-heat period can be combined with weather compensation control to adjust the pre-heating period in line with outdoor temperatures – the colder it is outside the longer the pre-heat period.
As every warehouse is different it follows that there is no ‘off-the-shelf’ heating solution that will provide best performance and best value for every warehouse. Instead, it is important that heating system is designed to suit the specific requirements of each project, taking account of all of the factors discussed above.
It will also pay to work with specialists in this field who have the experience and knowledge to deliver the most appropriate solution.