When it comes to specifying woodburning stoves, the ‘eco-equation’ doesn’t stop at the appliance’s efficiency rating, says Calvin May of HETAS. He explains how the layout of a room itself can be a game-changer, and delves into how to pair strategic appliance selection with optimal room placement
Modern homes are designed to be energy-efficient and are more air-tight than those of yesteryear – resulting in less of the necessary ventilation being available for solid fuel burning. Despite this, a wood-burning stove can still be a viable heating option in new builds or redeveloped properties – but only when specifying the right appliance for the space; and then positioning it in the optimum place for effective heating.
CHOOSING AN APPLIANCE
Traditional or convector open fires are not recommended in new build properties due to their low efficiency (37% and 60%, respectively) and impact this may have on the building’s overall energy efficiency. Freestanding or inset room heaters using solid fuel, including wood pellets, are ideal for maximum efficiency, with the added advantage of modern stoves producing around 90% fewer emissions than an open fireplace.
As of January 2022, the UK took significant steps to improve the sustainability and efficiency of solid fuel appliances. Under the new Ecodesign legislation, all new stoves and fireplaces must meet stricter efficiency and emission limits, including those for particulate matter (PM), organic gaseous compounds (OGC), carbon monoxide (CO), and nitrogen dioxide (NOx). Ecodesign rules complement existing air quality requirements for smoke control areas (SCA); however with SCA conditions being more stringent for particulates, it’s crucial to check with the relevant local authority or HETAS for any additional guidelines.
In line with ongoing government strategies to promote cleaner air and to better support consumer decisions in the purchase of environmentally responsible products, the HETAS ‘Cleaner Choice Approval Scheme’ offers a comprehensive register of those appliances meeting the most stringent performance limits for particulate emissions, with verified improvements of over 50% against the most robust requirements within the UK for particulates, and which appliances can be installed and operated within UK smoke control areas.
Having said that, do take advice from approved retailers and/or a registered heating engineer to make sure the appliance meets the necessary conditions required when burning the required fuel. Accurate sizing is also critical when choosing a heating appliance. Oversizing to fit a larger recess can lead to operating the stove outside of the manufacturer’s prescribed guidelines, which increases the risks of incomplete combustion and flue blockages, as well as increasing the overall operational costs for the user.
ROOM PLACEMENT CONSIDERATIONS
The positioning of a solid fuel stove in a room is crucial for optimum efficiency, safety and heat distribution. The ideal location is, generally, centrally within the room or home, where it can radiate heat evenly across the space. Placing the stove against an interior wall can assist in retaining warmth, while positioning it too close to an exterior wall may result in heat loss (particularly for restorations) however this is less of a concern with new builds where modern wall cavities and insulation work hard to retain heat within the building.
It’s essential to consider the flue design; a more straightforward, vertical flue is generally more optimal than a complex, angled one and will provide better flue draught to disperse products of combustion effectively. This makes it easier for engineers to service and maintain the appliance against the relevant servicing schedules.
Underfloor heating (UFH) is a popular choice for new builds or restoration projects – but this can also influence the position of the stove. The additional weight and heat of a stove, as well as its hearth, could adversely affect the UFH system’s pipes or cables, making these two systems generally incompatible. In these cases, the UFH manufacturer should be consulted to understand any limitations which the installation of a solid fuel stove may have.
Lastly, always observe all Building Regulations and clearance specifications from flammable materials to guarantee safe operation and ensure appliance manufacturer guidelines are followed at all times. A pre-installation survey carried out by a registered installer will help identify whether the proposed space maintains the safety of the installation when in use. Taking these factors into account can help maximise the efficiency and effectiveness of the appliance.
For those housebuilders and developers who aren’t aware, the installation should be undertaken by a trained and registered installer who will verify that the works comply with Building Regulations and standards. This includes factoring in an adequate flue system, air vents and correctly fitting a carbon monoxide alarm in the designated location.
Once completed, a Certificate of Compliance is provided, demonstrating that the installation complies with Building Regs and notifying (in England & Wales) the Local Authority Building Control Department (LABC) of the work that has been undertaken. Failure to notify the local authority can be an offence resulting in enforcement action.
The inclusion of wood-burning stoves in new builds, when done correctly, marries tradition with modern sustainability. But from the new Ecodesign guidelines to Building Regs and Health & Safety, there is plenty to consider from both a legal and technical perspective. By consulting with certified installers and retailers, educated decisions about appliance type and placement can be made; and developers can confidently incorporate traditional heating in a responsible way for our homes of the future.
Calvin May is head of technical services for biomass and solid fuel body HETAS (Heating Equipment Testing and Approvals Scheme)