Due to the high heating demand, energy savings in residential buildings in cold climates has played an important role in reducing carbon emissions. This study aims to investigate differences between the United States and Finland regarding characteristics and energy retrofit practices of current multifamily buildings (MFBs). The study focuses on net zero energy or nearly zero energy performance in cold and very cold climatic conditions. First an overview is presented of the status of multifamily housing stocks in the two countries, followed by an explanation of energy use patterns of residential buildings in both countries. Then, building codes related to energy efficiency in Finland and the United States are examined as well as major differences between the codes. Lastly, to further understand the different strategies and techniques used in energy retrofit projects, a dataset of 57 MFBs from both countries, both net zero energy buildings (ZEB) and nearly zero energy buildings (nZEB), were collected and analyzed. The preliminary results indicate three differences: (1) For the existing national MFB stock, the United States has a higher average energy use (EUI), at 266 kWh/m(2) per year (cold and very cold regions), compared to that of Finland, at 235 kWh/m(2) per year, (2) Finland has more stringent energy code requirements that contribute to lower energy use in studied case projects with a mean EUI of 80 kWh/m(2) per year compared to 148 kWh/m(2) per year in the U.S. sample,(3) In the Finnish studied cases, the heating and ventilation systems play a more critical role in explaining the building energy use differences in the sample, while in the U.S. cases, building envelope thermal properties explained the energy use intensity variations in the sample. Overall, the comparison of the Finnish and American cases showed that good technical practices from Finland can be learned to reduce the heating demand in cold and very cold climate regions of the United States. (C) 2021 Elsevier B.V. All rights reserved.

This article presents the field test of the developed demand response system installed in the central heating systems of existing apartment buildings. The buildings are occupied by students and located in Tampere, Finland, which is within the northern climate zone. The studied buildings are connected to the local district heating network. The presented demand response system takes into account weather forecasts, indoor temperatures and decreases in space heating temperatures when demand for domestic hot water is the highest. The owner of the buildings benefits from peak demand control and can save in fixed fees. If enough buildings would have this kind of demand response control system, there would be a decreased need for utility companies to use peak power plants that typically use fossil fuels for heat production. In this field test, the peak load decrease was 14%–15% on average. During the test, the heating period of February and March, the normalized energy consumption of eight buildings was reduced by 11%, which represents a 9% annual cut in energy, costs and greenhouse gas emissions. Demand Response (DR) heating aims to help in reaching the objectives of the National Energy and Climate Strategy for 2030.

This article presents a field test of how deep renovation affects indoor climate quality. The studied apartment building was built in 1968 and is located in Finland, within the Nordic climate zone. The deep renovation included façade repair with extra insulation, new windows with trickle vents, new balcony glass and doors, and the installation of an exhaust air heat pump into the existing mechanical exhaust air ventilation. The indoor climate conditions and building envelope tightness were measured before and after the renovation. As a result of these energy renovation measures, the building envelope tightness improved by nearly 40% and the uncontrolled supply of air (draughts) decreased by approximately 24%. The overall energy consumption of the building decreased by 45%. Above all, the long testing period gives credibility to the study. The field test brought up the challenge of supplying an adequate amount of fresh air. This article highlights the fact that windows are part of a mechanical ventilation system if fresh air is not controlled by being led through inlet ducts. The supply air flow and volume must be ensured by correctly dimensioned valves, and therefore we stress the importance of the technical cooperation of technical designers.

Residential construction and land use planning are changing in many countries around the world. There is a clear need for comprehensive, energy-efficient, cost-effective and CO2-neutral concepts meeting the latest energy and climate policy goals. This opens up new opportunities for the industry. Northern Finland has strong expertise in the field of wooden architecture and wood construction industry. By combining the existing high-tech expertise of enterprises, and strengthening the cooperation between SMEs, new value networks with significant international business potential can be created. This paper presents the Life City-concept, a holistic approach for smart and sustainable built environment, which is being created in the ongoing Life City-project. The concept consists of energy-efficient and modern wooden buildings in CO2-neutral neighborhoods and includes decentralized energy infrastructure with multiple renewable energy sources and smart networks. Life City-concept is a comprehensive export concept that adapts to the local climate conditions, but also considers the social needs of different communities. Other targets of the Life City-project include enhancing the export business knowledge and technical prerequisites of the collaborating SME companies. In cooperation with the companies, the project aims to develop new design, manufacturing and construction methods that enable improving the cost-effectiveness, environmental impact, energy-economy, microclimate and other living comfort issues of wooden buildings in different climate zones, taking also the climate change and resiliency issues into account. Preliminary project results show that the wood construction industry in Finland is not quite ready for exporting holistic concepts such as the Life City-concept, as more product development, knowledge and resources for export are needed. This finding applies especially to SME companies in the industry.