Janne Hirvonen

To achieve carbon neutrality in the EU, it is important to renovate the existing EU residential buildings for a higher building energy efficiency. This study examines the impacts of several novel renovation technologies on energy consumption, CO2 emissions and indoor climates in southern European residential buildings through building-level simulations. Three typical residential buildings in South Europe were chosen as the demo buildings to implement the novel technologies. The technologies were classified into passive, ventilation and generation packages, and then simulated independently under the intermittent and continuous heating schedules. Additionally, two final combinations of renovation technologies were also simulated to demonstrate the maximum energy and CO2 emissions reduction potential of the demo buildings. All novel retrofit technologies manifested obvious effects on the energy consumption and CO2 emissions. Nevertheless, the effects were significantly affected by the ...

Tämä raportti käsittää hukkalämpöjen hyödyntämisen nykytilanteen ja kehitysnäkymät, HUKATON-hankkeen tarkastelukohteiden simulointi- ja yhteiskehittämistyön tulokset, laajan liiketoiminnan kyselyn ja selvityksen liiketoiminnan näkymistä sekä suositukset tarkastelukohteisiin ja liiketoiminnan edistämiseen. Hankkeessa tutkittiin ja kehitettiin yhteensä kuutta kohdetta, joista kaksi on Helsingin kaupungin omistuksessa ja neljä yksityisomistuksessa Turun seudulla. Helsingin tarkastelukohteet valittiin yhteispäätöksellä, jonka tekoon osallistuivat asiantuntijat Helsingin kaupungin ympäristötiimistä, Heleniltä ja Aalto-yliopistosta. HUKATON-hankkeen päätavoitteena oli kehittää optimointilaskentaan ja yhteiskehittämiseen pohjautuvia uusia hukkalämmön talteenottoon perustuvia kokonaisratkaisuja, jotka tuovat rakennukset osaksi älykästä energiajärjestelmää kulutusjouston näkökulmasta. HUKATON-hankkeen tavoitteena oli lisäksi tuoda markkinoille täysin uusia digitaalisuuteen perustuvia palvelu...

In countries with high heating demand, waste heat from industrial processes should be carefully utilized in buildings. Finland already has an extensive district heating grid and large amounts of combined heat and power generation. However, despite the average climate, there is little use for excess heat in summer. Waste incineration plants need to be running regardless of weather, so long-term storage of heat requires consideration. However, no seasonal energy storage systems are currently in operation in connection with Finnish waste incineration plants. This study used dynamic energy simulation performed with the TRNSYS 17 software to analyze the case of utilizing excess heat from waste incineration to supplement conventional district heating of a new residential area. Seasonal energy storage was utilized through a borehole thermal energy storage (BTES) system. Parametric runs using 36 different storage configurations were performed to find out the cost and performance range of su...

This study examines how the energy renovation of old detached houses affects the hourly power consumption of heating and electricity in Finland. As electrification of heating through heat pumps becomes more common, the effects on the grid need to be quantified. Increased fluctuation and peak power demand could increase the need for fossil-based peaking power plants or call for new investments to the distribution infrastructure. The novelty in this study is the focus on hourly power demand instead of just annual energy consumption. Identifying the influence of building energy retrofits on the instantaneous power demand can help guide policy and investments into building retrofits and related technology. The work was done through dynamic building simulation and utilized building configurations obtained through multi-objective optimization. Deep energy retrofits decreased both the total and peak heating power consumption. However, the use of air-source heat pumps increased the peak pow...

Most Finnish residential buildings have been built before ventilation heat recovery options became mandatory. Exhaust air heat pumps are an effective way to reduce emissions, but they cannot cover all heating demand. Ground-source heat pumps can be designed to meet all loads, but they require corresponding amounts of space both above and below ground. This simulation study combines residential ventilation and sewage waste heat with a ground-source heat pump system to improve system sustainability and cost-effectiveness. A hybrid waste heat and ground-source heat pump system was shown to have 20% lower life cycle costs compared to a pure ground-source heat pump system. It also maintained sustainable ground temperature levels over the long term, while reducing above-ground space requirements by 95%.

In Finland, old apartments (1980s) contribute toward emissions. The objective is to reduce CO2 emissions to reach Europe’s targets of 2050. Three different centralized solar-based district heating systems integrated either with non-renovated or renovated old buildings in the community were simulated and compared against the reference city-level district heating system. The three proposed centralized systems were: Case 1: photovoltaic (PV) with a ground source heat pump (GSHP); Case 2: PV with an air-water heat pump (A2WHP); and Case 3: PV with A2WHPs, seasonal storage, and GSHPs. TRNSYS simulation software was used for dynamic simulation of the systems. Life cycle cost (LCC), CO2 emissions and purchased electricity were calculated and compared. The results show that the community-level district heating system (Case 3) outperformed Case 1, Case 2, and the city-level district heating. With non-renovated buildings, the relative emissions reduction was 83% when the reference energy syst...

Energy retrofitting of buildings shows great potential in reducing CO2 emissions. However, most retrofitting studies only focus on a single building type. This paper shows the relative potential in six Finnish building types, to identify possible focus areas for future retrofits in Finland. Data from previous optimization studies was used to provide optimal cases for comparison. Energy demand of the buildings was generated through dynamic simulation with the IDA-ICE software. The cases were compared according to emissions reduction, investment and life cycle cost. It was found that, in all buildings, it was possible to reduce emissions cost-neutrally by 20% to 70% in buildings with district heating and by 70% to 95% using heat pumps. Single-family homes with oil or wood boilers switching to heat pumps had the greatest emission reduction potential. More stringent requirements for energy efficiency could be mandated during building renovation.

In the pursuit of mitigating the effects of climate change the European Union and the government of Finland have set targets for emission reductions for the near future. This study examined the carbon emission reduction potential in the Finnish energy system with power-to-heat (P2H) coupling of the electricity and heat sectors with different housing renovation levels. The measures conducted in the energy system were conducted as follows. Wind power generation was increased in the Finnish power system with 10 increments. For each of these, the operation of hydropower was optimized to maximize the utilization of new wind generation. The excess wind generation was used to replace electricity and heat from combined heat and power production for district heating. The P2H conversion was performed by either 2000 m deep borehole heat exchangers coupled to heat pumps, with possible priming of heat, or with electrode boilers. The housing stock renovated to different levels affected both the e...

To mitigate the effects of climate change, the European Union calls for major carbon emission reductions in the building sector through a deep renovation of the existing building stock. This study examines the cost-effective energy retrofit measures in Finnish detached houses. The Finnish detached house building stock was divided into four age classes according to the building code in effect at the time of their construction. Multi-objective optimization with a genetic algorithm was used to minimize the life cycle cost and CO2 emissions in each building type for five different main heating systems (district heating, wood/oil boiler, direct electric heating, and ground-source heat pump) by improving the building envelope and systems. Cost-effective emission reductions were possible with all heating systems, but especially with ground-source heat pumps. Replacing oil boilers with ground-source heat pumps (GSHPs), emissions could be reduced by 79% to 92% across all the studied detached...

This study examined the cost-optimality of energy renovation on Finnish apartment buildings of different ages, built according to different energy performance requirements. Multi-objective optimization was utilized to minimize both CO2 emissions and life cycle cost (LCC). IDA-ICE simulations were performed to obtain the hourly heating demand of the buildings. Four building age classes and three heating systems (district heating, exhaust air heat pump and ground-source heat pump) were separately optimized. With district heating, it was possible to reduce emissions by 11%, while also reducing LCC. With heat pumps cost-savings could be achieved while reducing emissions by over 49%. With maximal (not cost-effective) investments, emissions could be reduced by more than 70% in all examined cases. In all cases, the cheapest solutions included solar electricity and sewage heat recovery. In old buildings, window upgrades and additional roof insulation were cost-effective. In new buildings, d...

Demand response has been studied in district heating connected buildings since the rollout of smart, communicating devices has made it cost-effective to control buildings’ energy consumption externally. This research investigates optimal demand response control strategies from the district heating operator perspective. Based on earlier simulations on the building level, different case algorithms were simulated on a typical district heating system. The results show that even in the best case, heat production costs can be decreased by only 0.7%. However, by implementing hot water thermal storage in the system, demand response can become more profitable, resulting in 1.4% cost savings. It is concluded that the hot water storage tank can balance district heating peak loads for longer periods of time, which enhances the ability to use demand response strategies on a larger share of the building stock.

Solar electricity is growing very popular in the world, but it has some problems in matching of generation and demand both in hourly and seasonal levels. In northern latitudes the problem is especially significant, as the difference between solar availability in winter and summer is very large. Cooling needs do not increase electricity demand in summer as much as in southern locations, while there is a high demand for heating in the winter when solar power is not available.

ABSTRACT All over the world, including Japan, there are targets to decrease building energy consumption and increase renewable energy utilization. Combined heat and power (CHP) plants increase energy efficiency and are becoming popular in Japan. CHP plants produce both heat and power simultaneously, but there is not always a need for both. A cluster of several different buildings can increase total efficiency and reduce primary energy (PE) consumption by sharing excess heat and electricity between neighboring buildings. If the generated energy comes from renewable sources, energy sharing makes it easier to reach the net zero energy balance. By adjusting CHP sizes and operation patterns, the wasted heat and primary energy consumption can be minimized. Energy sharing has been explored in situations with identical buildings and centrally administered energy systems before, but not with different building types with separate systems. In this study, a cluster of Japanese office and residential buildings were combined to allow heat and electricity sharing based on cogeneration, using individually prioritized control (IPC) systems. TRNSYS simulation was used to match energy generation with pregenerated demand profiles. Absorption cooling was utilized to increase the benefits of local heat generation. Different CHP operation modes and plant sizes were tested. The benefit of surplus energy sharing depends on the CHP capacities and the fuel type. When using biogas, larger CHP plants provided lower total primary energy consumption, in the most extreme case lowering it by 71%, compared to the conventional case. Using natural gas provided only a 6% decrease. The savings resulting from energy sharing were between 1% and 9% with biogas and between 1% and 6% using natural gas. The least amount of PE was consumed by having large CHP plants with biogas, due to the value of renewable electricity. Using natural gas, thermal tracking had the lowest PE consumption.

ABSTRACT The objective of this study was to examine the effect of production-based support schemes on the economic feasibility of residential-scale PV systems (1–10 kW) in Finland. This was done by calculating the payback time for various sizes of newly installed PV systems for a Finnish detached house with district heating.

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