Abstract
Wood stoves constitute an important component of residential space-heating in cold-climate countries, particularly in Norway, where a substantial proportion of households are equipped with a wood stove.These stoves are used as a primary or supplementary heating source. In Norway, wood stoves often complement electricity-based systems for space heating (which dominate Norwegian residential heating due to historically cheap electricity from hydropower). Wood stoves influence both the electric power and the energy use of buildings. From a household perspective, wood stoves reduce electric energy consumption. Although the price of wood is highly variable (e.g., correlated with the electricity price, depending on the location and the supply chain), wood stoves can be less expensive to operate than electric panel heaters. This can lead to reduced heating energy costs. From an electricity production and grid perspective, wood stoves help reduce the stress on electricity generation, particularly during cold periods when the need for electricity is at its maximum. By substituting for electric space heating, which represents the substantial use of electricity in Norwegian homes, wood stoves can lower household electricity bills and reduce peak loads on the grid, helping prevent overloads or blackouts. Finally, wood stoves have a direct impact on the indoor thermal environment and occupant comfort, providing additional flexibility in managing the indoor climate and improving thermal satisfaction.
The widespread presence of wood stoves in Norwegian homes has the potential to play a decisive role in shaping the overall profile of residential electric power consumption. Although the impact of wood stoves on building electrical energy consumption has been extensively studied and well documented, the role of wood stoves in residential electrical power consumption has not yet been fully quantified empirically using measured data. Therefore, it is necessary to understand how wood stoves interact with electric heating and household appliances under varying outdoor temperatures. Empirical experiments capable of capturing these interactions can provide valuable insights into the real-time substitution effects between wood stoves and electric heating. This understanding is particularly important for quantifying the flexibility potential of residential buildings during peak times, when the electric grid operates at its highest capacity.
Wood stoves function as powerful point-source heating devices, typically providing a nominal heating capacity of 6–8 kW, allowing rapid reheating of indoor spaces. This capability, combined with older heating habits, can lead households to maintain lower indoor temperatures when the stove is not in use and higher temperatures when it is operating. The full impact of wood stoves on household thermal comfort depends on multiple factors, including occupant behavior and building characteristics, which cannot be fully captured through simulations and therefore require empirical data. Another limitation of building energy simulations is that they generally assume that the indoor temperature and comfortare independent of the heating system. Consequently, while simulations provide valuable insight, they may overlook certain comfort-related dynamics observed in real households. In addition, simulation-based studies have raised concerns about the integration of wood stoves into modern, highly insulated buildings, particularly regarding their thermal performance and implications for occupant comfort. In such energy-efficient and airtight building envelopes, excess heat from wood stoves can easily lead to overheating if the stove is oversized. This may cause users to modulate the heat output by reducing the air supply or the amount of wood, resulting in lower combustion quality, increased emissions, and reduced energy efficiency, highlighting the importance of appropriate stove sizing.
In this regard, the present study investigates the influence of wood-burning stoves on Norwegian households, with a dual focus on reducing electric power and improving the indoor environment. To address these objectives, two complementary approaches are employed. The first approach utilizes real measurements in two ways: high-resolution data from individual houses, including smart meter readings, space heating power, wood stove surface temperature, and indoor and outdoor temperature; and aggregated hourly electricity load data from smart meters of households within regions, accompanied by outdoor temperature and general information about households. The second approach relies on data from a nationwide questionnaire survey, designed to complement the measured data by capturing variables that are not easily quantifiable by sensors, such as thermal sensation and comfort, allowing a broader, more general, and cost-effective analysis. To analyze the impact of wood stoves on both household electricity demand and thermal comfort, a baseline was established using the dominant heating system in Norwegian buildings, electric panel heaters, and then the comparison was extended to other technologies, particularly heat pumps, to account for interactions between different heating strategies.
The impact of a wood stove on the electricity consumption of a single Norwegian household was analyzed using detailed room-level data from a semi-detached building in Trondheim, Norway, equipped with both electric panel heaters and a wood stove for space heating. The analysis revealed a temporal coincidence between the operation of the wood stove and the use of electrical appliances throughout the day. Since wood stoves are manually operated, occupants tend to use them during periods of high activity when electric appliances are also in use. Consequently, the peak power of electric appliances does not coincide with the peak power of the electric radiators, leading to a reduction in the maximum total household electricity demand equivalent to the nominal power of the electric radiator installed in the same room as the wood stove (here, approximately 1 kW). Specifically, the maximum total power decreased from 5 kW when the wood stove was not allowed to be used to 4 kW when the stove as allowed to be used. In conclusion, this positive correlation between the use of electric appliances and wood stoves should make the reduction of the household’s total electric power more important during peak hours.
The influence of wood stoves on aggregated electricity use was based on the analysis of smart meter data from more than 300 detached houses equipped with electric panel heaters. The sample was divided into two statistically comparable groups: those with wood stoves and those without. To compare the aggregated hourly demand between the two groups, a linear regression was performed with the average specific power (power divided by the gross floor area of the house) as the dependent variable and the outdoor temperature as the independent variable. The findings indicate a substantial impact of wood stoves on residential electricity demand, with reductions of up to approximately 10 W/m2 at outdoor temperatures around −10 ◦C. These effects are most pronounced during peak hours, when households are typically occupied, though reductions are also observed at night, when stoves are unlikely to be in active use. This suggests that ownership of wood stoves, as data on stove usage frequency was unavailable, has a significant influence on the reduction of aggregated electric power. Then, the analysis was extended to detached houses with an air-to-air heat pump supplemented by electric panels. The influence of the wood stove on the electric power is shown to be significantly lowered when an air-to-air heat pump is present, demonstrating the influence of the main heating system on the stove’s power reduction potential. In conclusion, when considered on a larger scale, wood stoves therefore contribute to reducing stress on the electrical grid by substituting biomass for electricity during critical periods.
Finally, a questionnaire survey was developed to provide complementary information on indoor thermal conditions (including temperature, thermal sensation, and comfort in living rooms and bedrooms), wood energy use and stove operation patterns, as well as motivations for using wood stoves. The responses comprised more than 400 respondents from all over Norway. To analyze and model the responses, generalized linear models (GLMs) and cumulative link models (CLMs) were applied to examine wood stove use patterns, seasonal dependence, user motivations, perceived comfort, and indoor temperature. The results confirm previous measurement-based findings, revealing a pronounced evening peak in wood stove usage that coincided with the highest grid loads, along with substantial variability between households in the frequency and intensity of wood stove operation. When different heating systems were compared, living rooms in homes with wood stoves exhibited greater temperature fluctuations: lower in periods without stove operation, higher in periods when the stove is in use. This can explain why the electric power of buildings equipped with a wood stove is, on average, also lower outside periods when the stove is used. Furthermore, higher thermal comfort was reported when the stove was operated, particularly in homes primarily heated by electric panels. However, overheating affects about 25% of respondents and increases to nearly 50% in highly-insulated buildings, highlighting the importance of proper stove sizing and thermal energy storage in the stove envelope.
Together, these findings provide robust empirical evidence on the role of wood stoves in shaping household electricity demand, heating practices, and the indoor thermal environment and comfort in Norwegian dwellings. The results have important implications for building energy modeling, residential energy policy, energy planning, and the design and integration of biomass-based heating systems, particularly with respect to reducing peak electricity demand and improving energy flexibility in coldclimate regions.