How To Heat An Industrial Building

such as a warehouse or factory

This guide will help you navigate through the various choices and decisions you will be faced with in selecting the ideal design and installation for a heating system in an existing or new industrial building such as a factory, warehouse or workshop.

Background

There are many external factors to bear in mind when selecting the heating system that you will be installing into your industrial building. There is some legislation and guidance governing Health & Safety at Work and suitable operating temperatures for employees. Additionally your, or your employer/client’s attitude to environmental issues and Corporate Social Responsibility may influence your selection criteria at some stages of the process. These will generally be at the fuel source and building usage stages which we will discuss first. Additionally there are various government schemes designed to encourage uptake of green energy technologies (Feed in Tariffs, Renewable Heat Incentive etc.)

Contents

  1. Building type and usage
  2. Heat Loss calculation
  3. Heat fuel source
  4. Heater product selection
  5. Radiant ‘spot’ heating

 


Building type and usage

The building type and its intended usage is the primary driver of heating system selection. It is important at the outset to clearly establish this with your manager/client, and consideration should be given not just to the current plans but any possible future changes in usage. The key point to ascertain is what the primary driver in trying to heat the property is.

Heating people

In most cases this will be to provide comfortable working conditions for staff and visitors. This can vary from simple working conditions, but could also impact on the business’s turnover if customers visiting the property made buying decisions based on the customer journey. In any case it is important to establish what kind of activity the people in the building will be performing as this will determine the temperature required according to the following table

ActivityRecommended temperature
Rigorous physical effort13⁰C
Moderate moving about16⁰C
Seated at a desk18⁰C

factory industrial worker

It is also worth establishing where these activities will take place as the option to ‘spot heat’ limited areas of the industrial building could provide a very economical solution, though of course future proofing the solution will require some certainty that this won’t change over time.

Heating building contents

In some cases the heating requirement may not be based on the building occupants, but rather it’s contents.

We recently installed a steam based heating system into a 200,000 sq. ft. warehouse which was storing wine worth millions of pounds. In this case the primary design criteria was to ensure a stable moderate temperature to preserve the wine quality.

Constant or regular use

If the building is not in constant use then it is important to establish working patterns and when heat will be required. If, however, the requirement is to heat the building is a 24/7 then concerns about heat up time don’t apply.

Building internal purpose

It is also important to understand the works or processes being undertaken in the building as many industrial machines generate significant heat when operating and this can impact on the heat load required. Conversely heat can be lost in a building where delivery doors are frequently opened with a resulting loss of warm air.

Consideration should also be given to any process specific requirements of the system such as air movement restrictions, noise level limitations, any flame proof or explosive proof stipulations, moisture or dust protection factors and so forth.

factory doors impact heat loss

Ownership

Finally, consider whether the building is owned or leased by your firm/client and whether this, or other factors, affect the appetite for capital expenditure over operating costs. You should properly understand the pay-back period required for energy saving investment options.

These considerations will impact on your choices and so it is important to establish these at the outset.

 

 


Heat Loss calculation

The first step in preparing design options for evaluation is to calculate the ‘heat loss’ of the building.

The heat loss is the amount of energy required to heat a building from an external ambient temperature, usually a worst-case estimate, to a required internal temperature.

This is known as the temperature lift or more commonly the Δt (delta t).

The calculation is based on the size of the building in volume of m³, thus you require the length, width and height of the building.

The next important factor is the fabric of the building: what are the floor, walls and roof constructed from, are they all external walls, how much glazing/windows is present and how many access doors and how often are these opened? Using this information many companies can attribute U-values to the building and from there convert the Δt into a kilowatt (kW) requirement. At Turnbull & Scott we can easily provide this calculation to assist your project.

glazing impacts heat loss

A small house/cottage would typically have a heat loss of 18–25kW. Obviously an industrial building could be significantly greater but generally speaking any heat loss less than 50kW can be satisfied by domestic style equipment and contractors. From 50kW to 1Mw heat loads it is generally seen as an Industrial HVAC style project.

It is worth mentioning at this stage that if you occupy a large building such as a warehouse but only require heat in a small area where people are working –at a bench for example – you should consider radiant heat, which directs heat exclusively at the workspace. If this is a suitable solution your heat loss will be calculated somewhat differently.

 

 


Heat fuel source

Having established the heat loss requirement you should now consider the fuel source. In an existing building being refurbished this may already be dictated by the existing system, however if not this is an important consideration.

The options can be grouped into:

ElectricHeavy-Duty-Unit-Heater

Smaller buildings/units may lend themselves to an electric heating system which is usually cheaper to install but less efficient to run. Electricity costs tend to range in the £0.10–0.15 per kW. For this reason, and the lack of availability of high voltage electricity supply, it is unlikely to be suitable for larger buildings or kW requirements. Typically electric heating systems are not an option beyond 200 kW.

 

Natural gas

The most common fuel source for industrial properties is natural gas. Most industrial estates will already have a gas supply available in close proximity to the buildings and at a cost per kW natural gas is the cheapest fuel source at c£0.04 per kW. The natural gas can be used to fire a burner on a boiler to generate hot water or steam which is then piped to heat emitters or radiators within the building much like a domestic central heating system.

Alternatively the gas can be piped directly to what are known as ‘direct fired warm air heaters’. These are typically ceiling mounted or floor standing and consist of a burner from which a naked flame is used to heat air which is then expelled at force by an integral fan. Direct fired systems are generally cheaper to install than a boiler system but are more expensive to run and require individual ventilation solutions, gas safety requirements and regular servicing.

Heating oil or LPG

Where an industrial unit is located ‘off grid’ (i.e. there is no natural gas available) the use of heating oil or LPG will need to be considered. These work similar to the natural gas options but will require the installation of a storage tank and regular monitoring and refilling. These days many fuel suppliers offer remote monitoring and automatic re-ordering of oil or LPG. Cost per kW of heating oil or LPG are higher as delivery to remote locations raises costs.

Biomass or other renewables

The UK government supports the use of biomass boilers through the Renewable Heat Incentive (RHI) scheme. The scheme is designed to make biomass competitive with natural gas. However it is more likely to be adopted for off grid industrial buildings as an alternative to heating oil or LPG. In a biomass system a special boiler is required. These boilers are fed wood (logs, wood chip or wood pellets) from a fuel store via a system of augurs or other mechanical system. The wood is burned within the boiler from which hot water or steam is generated. Thereafter the system operates like any boiler system. Biomass has the benefits of reducing operating costs (subject to RHI), reducing CO2 emissions and enhancing a company’s ecological reputation. They are however more expensive to install.

The use of other renewable technologies is also supported by the UK government. Combined Heat and Power (CHP) machines are becoming increasingly popular for industrial applications as they generate both heat and electricity. If your process requires substantial electrical power it may be worth considering a CHP unit as a solution.

Other renewable technologies include solar thermal panels or ground source heat pumps both of which generate hot water, though the latter would be at a much lower temperature than a normal heating system and thus requires greater heat emitters (see later) within the building. Either of these options can be used in conjunction with a traditional boiler system to reduce running costs. Ground source heat pumps may also qualify for RHI payments from the UK Government.

 

 


Heater product selection

The selection of the internal heat emitters or heaters is usually driven by the choice of heating fuel source and the layout of the building. Having calculated the heat loss in kW required to heat your building and chosen a heat source such as a boiler or CHP it is important to select heat emitters sufficient to consume and distribute the correct amount of heat to the correct location.

Building shape and layout

Building shape and layout will dictate the number and location of the heaters. If, for instance, your building requires 200kW of heat you could select a 200kW direct fired gas heater and place it in the centre of the building. If the ‘throw’ of the heater is not sufficient to reach all four walls, or there are obstacles such as racking, this may not be effective and you may need to select four 50kW heaters and locate them strategically around the building. Four heaters will obviously require more installation and servicing costs and so the choice of heating source and heater product can often be an iterative process.

Sources of heat loss

In choosing the location for your heaters it is worth considering the sources of heat loss and installing measures to reduce or counteract these. For example if loading bay doors are left opened for long periods of time installing automatic closing mechanisms based on sensors, over door heaters or air curtains or simply poly-curtains. Similarly in a high building where heat can get trapped in the eaves the inclusion of de-stratification fans to circulate the warm air back to floor level can result in significant savings in both operating costs but also the number and size of heaters required from the capital expenditure budget.

 

In general there are four heat source categories which drive the choice of heat emitter type and building layout drives the size and quantity decision.

Electric: If you have chosen to heat the building using electric heaters the product selection is relatively straight forward. There is no boiler installation required and you simply need to select suitable heaters based on throw and building size. Generally speaking electric heaters tend to be small with a maximum output of c40kW.

Direct fired: Gas or oil burning direct fired heaters avoid the costs of installing boilers and provide quick and effective heat in high volume. They tend to have a high throw and so in an open environment where there are no obstacles to air movement a small number of powerful units can be very effective. They do require gas/oil pipework to each unit and will require ventilation to extract the fumes from the building as well as bring fresh air into the unit.

Wet system: The use of a boiler (oil, gas or biomass) will generate hot water at temperatures of c80⁰C or steam, which will then be piped to a series of heaters. The choice of heaters will be based on the space to be heated. Traditional radiators suitable for the home or office may not be optimum for a large space, and typically a fan assisted unit heater will be required. These consist of a heating battery or radiator typically housed in a metal enclosure, with air forced through it by a fan, which distributes the warm air outward from the front of the unit heater. Recent developments in synthetic materials has resulted in lightweight polypropylene casing being used to produce lightweight, easy to install unit heaters at a cheaper cost, such as the Sonniger Water Fan Heater.

Water-Fan-Heater

 

As an alternative to a number of unit heaters located throughout the building you can install a large heating battery and fan close to the boiler and use a duct system to transport the warm air around the building. In some cases this arrangement is achieved by installing an Air Handling Unit (AHU) on the roof of the building to perform the same task. One benefit of the AHU is it can provide chilled air during summer months.

Underfloor heating: This has so far had limited take up in industrial buildings, probably due to the age of our industrial building real estate and the harsh demands on floors from vehicle traffic or load bearing machinery. They are particularly suitable for use in conjunction with heat pumps. Heat pumps produce hot water at a much lower temperature than a boiler system (typically 50⁰C) and so require a much greater surface area of heat emitters. A combination of heat pump and underfloor heating can provide a constant supply of economical heat but capital costs of installation may be prohibitive.

 


Radiant ‘spot’ heating

In many large factories or warehouses there is a requirement to keep people working in a small area warm. They may be using computer terminals in a warehouse or performing light assembly tasks at a bench, for example. The use of a radiant heating solution allows you to achieve ‘spot’ heating as heat energy is emitted from a warm element, such as a wall or overhead panel, and warms people and other objects in rooms rather than directly heating the air. This is far more economical than heating the entire building.

The internal air temperature for radiant heated buildings may be lower than for a conventionally heated building to achieve the same level of body comfort, when adjusted so the perceived temperature is actually the same.

Decreased circulation of air inside the room

One of the key advantages of radiant heating systems is a much decreased circulation of air and the corresponding spreading of airborne particles. Radiant overhead panels are mostly used in production and warehousing facilities or sports centres; they hang a few meters above the floor and their surface temperatures are much higher. They are available in direct gas fired, water, steam and electric options.

No heat loss calculation required

Selecting your radiant heaters does not require a building heat loss calculation; simply refer to manufacturer’s technical specification to determine how many you require and at what height they should be installed.

 

Heating, ventilation and air conditioning (HVAC) suppliers can usually provide you with a free heat loss calculation and advice on the best heating solution to meet your exact requirements.

Get your free industrial heat loss calculation