Biomass boiler district heating applications are where several buildings or zones are heated by a single biomass boiler (or wood burning boiler, log boiler, wood chip boiler or wood pellet boiler) via a heat 'network'.
This involves circulating hot water to several buildings or 'Zones' via underground, pre-insulated pipes (also called 'heat main').
The heating circuit within each building or zone is isolated from the biomass boiler which provides the main source of heat, with no combustion occurring at the point of use. Instead, a control system such as a Treco Heat Interface Unit (HIU) is used in place of a biomass boiler, which offers all the control that a full boiler would give at the point of use, but in a far smaller package.
There are a number of advantages to biomass district heating.
Fuel cost and CO² savings magnified
Biomass per se offers CO² savings of up to 96% and fuel cost savings of up to 80% versus fossil fuels. District heating with biomass can drive further economies of scale and exponentially lower emissions than with multiple localized boilers. Where the installation can be on a scale of 50-400kW, this can become highly environmentally and economically beneficial with savings multiplied across multiple units, buildings or zones.
Building Regulations, RHI and Code for Sustainable Homes Compliance
For housing developers, these CO2 savings will give a significant advantage in Code for Sustainable Homes Developments and easy compliance with Document J of the Building Regulations (Combustion appliances and fuel storage systems) and Document L of the Building Regulations (the Conservation of fuel and power).
The lower carbon footprint synergies of a high efficiency biomass boiler heating several zones of buildings, the use of renewable fuel and district heating combined can also ensure easy compliance maximum emission levels. The tougher maximum emission levels soon to be introduced in the Building Regulations and the accreditation criteria for entry into the Renewable Heat Incentive are due to come in during summer 2013 will specify maximum emissions of 30g/GJ particulate matter and 150g/GJ nitrogen oxides.
Commercial landlord advantages
Biomass district heating offers commercial landlords the opportunity to sell low cost heat to tenants or to sell biomass heat at a profit.
These stem from the heating circuit within each building or zone being isolated from the biomass boiler providing the main source of heat.
Heat usage levels can be monitored by the quantity of hot water used in the relevant zone being measured via a heat meter. This allows delivered heat to be accurately and easily billed.
Tenanted properties which are heated by renewable energy can also be easier to let and to keep let, with less time left unoccupied and not generating rental income.
Control and safety at the point of use
With combustion only occurring centrally, the occupants or tenants in each individual zone are given a safe environment in which to live or work, with no annual safety checks, carbon monoxide alarms or health and safety provisions required at the point of use. This gives tenants all of the controls they would expect from a full boiler system, but in a smaller and safer package.
This makes biomass district heating advantageous for use in care homes, social landlords, hospitals, schools or any other applications where the owners, Energy Service Company (ESCO) or maintenance provider will have a legal duty of care and safety to building occupants.
Ease/lower costs of maintenance and servicing
In addition, district heating offers a range of administrative benefits, time and cost savings, as well as huge potential maintenance and servicing advantages.
Money for Green Heat: The RHI
Available for domestic properties now
Installations featuring a single boiler serving a single domestic property will not be eligible for the Renewable Heat Incentive (RHI) until April 2014.
However, district heating can offer homeowners access to the fuel security and generous payments that commercial, non-profit, public sector and charitable organisations currently enjoy. Where a single boiler serves more than one property (i.e., with more than one Council Tax Account), the installation will be deemed as commercial and will be eligible for 20 years of payments from the commercial RHI, which has been available since November 2011.
Remote meter reading and heating control by web based applications or GSM are possible, as are remote diagnostics to ensure reliable operation. This can provide landlords (who have multiple tenanted properties) with ease of management, particularly if their properties are in different geographic locations. This can offer time and financial savings from not having to travel to remote locations.
In addition, with no fuel usage at the point of use, landlords can continue to provide warmth and comfort to tenants during extreme weather conditions, when a fuel delivery may not be possible and to provide a service to tenants which avoids the effort of them handling fuel.
Key features and components
Some of the key components of district heating schemes include:
- Buffer tanks
- Fuel stores
- Boiler houses
- Expansion vessels/tanks
- Pre-insulated underground pipe
- Flue systems
- Heat meters
- Remote monitoring systems
- All associated electric and plumbing connections, pumps, valves