Granlund (Finland)

The recent COVID-19 pandemic has heightened awareness of how airborne pathogens spread in indoor environments. Room air cleaners, when properly selected, can increase the non-infectious airflow in a room and help control infection transmission by reducing the concentration of airborne pathogens in indoor air. In an intervention study, 45 portable air cleaners were installed in 40 rooms at two kindergartens in Helsinki, Finland, to investigate the effect of portable air cleaners (PACs). Their power consumption was continuously monitored using smart plugs. We compared the energy costs of the PACs with those of the HVAC system. The PACs consumed 5784 kWh and 3256 kWh of electricity annually in kindergarten A and B, respectively. At an electricity price of 0.16 €/kWh, their energy costs were 911 € and 524 €. To achieve the same increase in equivalent clean airflow rate with the HVAC system, we would need to spend 4831 € and 3114 € on electricity and heating energy in kindergarten A and B, respectively. We concluded that PACs can be a flexible and cost-effective way to reduce the concentration of airborne pathogens in indoor premises during sudden incidents, such as a pandemic.

To achieve a successful integration of fluctuating renewable power generation, the power-to-heat (P2H) conversion is seen as an efficient solution that remedies the issue of curtailments as well as reduces carbon emissions prevailing in the district heating (DH) sector. Concurrently, the need for storage is also increasing to maintain a continuous power supply. Hence, this paper presents a MILP-based model to optimize the size of thermal storage required to satisfy the annual DH demand of a community solely by P2H conversion employing renewable energy. The DH is supplied by the optimal operation of a novel 2-km deep well heat pump system (DWHP) equipped with thermal storage. To avoid computational intractability, representative time steps with varying time duration are chosen by employing hierarchical agglomerative clustering that aggregates adjacent hours chronologically. The value of demand response and the effect of interannual weather variability are also analyzed. Numerical results from a Finnish case study show that P2H conversion utilizing small thermal storage in tandem with the DWHP is able to cover the annual DH demand, thus leading to a carbon-neutral DH system and, at the same time, mitigating the curtailment of excessive wind generation. Compared with the annual DH demand, an average thermal storage size of 29.17 MWh (2.58%) and 13.99 MWh (1.24%) are required in the business-as-usual and the demand response cases, respectively.

Building energy efficiency, construction cost, life cycle cost, and carbon emission are the best interests of users, owners and different vendors. This study assessed the energy performance (EP) related investment and operational energy cost of Kouvola housing fair NZEB. Data from 12 new detached houses were collected, which fulfilled the energy certificate class of B according to the Finnish nearly zero energy building (NZEB) regulation. Besides, emission from building materials, construction and energy use during 50 years of one model building were estimated, aiming to compare the life cycle emission from wooden building, insulated concrete building, blockhouse and log house. The results showed that the total construction cost was independent to EP-value and even had a slightly negative correlation to the EP-value. The average EP-value of 12 buildings was slightly higher than that of buildings in Tampere housing fair 2012, which showed no improvement of nearly zero energy building (NZEB) guidelines since 2012. Energy performance related cost dependency in specific cost categories was shown so that EP-value improvement by 40 units increased less than 2% of construction cost. Electricity had a significant contribution to CO2emission while local district heating was based on renewables. Material emissions contribution was 32-48% of total emissions, and wooden buildings showed lower carbon footprint compared to other building structures.

The building sector plays a remarkable role in decreasing of the overall global CO2 emissions since as much as 30% from the total global CO2 emission are generated in buildings. Demand response provides one possibility to tackle the problem. It can be used to decrease CO2 emissions in entire energy system in addition to providing energy cost savings for building owners and energy companies. In this study, the demand response potential was estimated in an educational office building that was heated by district heating. The potential was defined in respect of energy cost savings, energy flexibility and thermal comfort. Model predictive control was developed, which utilized the dynamic hourly district heating prices. The MPC algorithm written in the Matlab software, predicted the future heating demand while the optimization algorithm NSGA-II minimized the heating energy cost, maximized the energy flexibility and maintained acceptable thermal comfort by changing the space heating temperature setpoints. The operation of the MPC algorithm was tested in the IDA ICE 4.8 simulation software. As a result, the annual district heating energy costs could be reduced by 4.2% compared to the reference case with constant space heating temperature setpoint of 21 °C. The maximum flexibility factor attained was 14%. Acceptable level of thermal comfort was maintained throughout the simulation time.