Cold Winter Days Research Articles

Exploratory Analysis of a Novel Modular Green Wall’s Impact on Indoor Temperature and Energy Consumption in Residential Buildings: A Case Study from Belgium

One possible solution that mitigates the effects of climate change is the implementation of vertical greenery systems, which have the potential to reduce the need for cooling and provide energy savings for heating. This paper evaluates the effects of an innovative modular green wall on indoor temperature and energy use in a residential case study building. This research was carried out on a residential house in the city of Ghent, Belgium, whose southwest facade is covered with a specific type of modular green wall (a structure with a specific substrate and plants that have the ability to purify water so that it can be reused in the house). The monitoring process included four different temperatures (in front of and behind the green wall, in the substrate, and on the wall without greenery) during winter and summer periods. To analyze the effect on the internal temperature and energy use, a DesignBuilder simulation model was built and validated against these experimental results. This green wall has proven to have the greatest effect during the hottest summer days by reducing the indoor temperature by up to 3.5 °C. It also effectively increases the indoor temperature by up to 1.4 °C on a cold winter day, leading to energy savings of 6% on an annual basis.

The association between short-term temperature variability and mortality in Virginia

The objective of this study is to determine the relationship between short-term temperature variability on neighboring days and mortality. The change in maximum temperature in Northern Virginia, Richmond, Roanoke, and Norfolk, Virginia, on neighboring days was calculated from airport observations and associated with total mortality over a multi-county area surrounding each weather station. The association between day-to-day temperature change and mortality, lagged over a 28-day period, was analyzed using distributed lag non-linear models that controlled for air quality, temporal trends, and other factors. Days following large temperature declines were associated with an increased risk of mortality in three of the four locations, and temperature increases were linked to higher mortality risk in two cities. For example, the relative risk of mortality for a 12°C daily temperature decline (1st percentile) was 1.74 [0.92, 3.27] in Roanoke and 1.16 [0.70, 1.92] in Richmond. The net effect of short-term temperature increases was smaller, with the largest relative risk of 1.03 [0.58, 1.83] for a 12°C increase (99th percentile) in maximum temperature in Norfolk. In Richmond and Roanoke, there was an observed lagged effect of increased mortality (maximum relative risks varying from 1.08 to 1.10) that extended from 5 to 25 days associated with large temperature declines of 15°C or more. In contrast, there was a strong and immediate (lag 0–3 day) increase in the risk of mortality (1.10 to 1.15) in northern Virginia and Norfolk when the temperature increase exceeded 10°C (short-term warming). In general, consecutive day warming had a more immediate mortality impact than short-term cooling, when the peak mortality is lagged by one week or more. However, cooling of at least 10°C after a hot (summer) day reduced mortality relative to comparable cooling following a cold (winter) day, which is associated with high mortality. This differential mortality response as a function of temperature suggests that there is some relationship between average temperature, temperature variability, and season. The findings of this study may be useful to public health officials in developing mitigation strategies to reduce the adverse health risks associated with short-term temperature variability.

Should end-users take their clothes off inside on a cold winter's day? Sustainability pressures on district heating professionals in Denmark

This research explores how district heating (DH) sector professionals /employees experience the low-carbon energy transitions-related change processes in the Danish heat supply sector. Enquiry draws upon mixed data collected among DH employees from 148 utilities. Geels’ triple embeddedness framework conceptualizes the connections between regime-level actor experiences of niche- and landscape-level pressures, sustainability imperatives, and the associated change processes. This neo-institutionalist perspective finds that the historically stable DH regime-level institutions are being destabilised. It also reveals the tensions and change inertia associated with, for example, sunk costs, infrastructural path dependencies, and professional culture. For the DH professionals, and regime-level actors, these destabilization processes challenge what were previously core regime-level professional practices, skills and taken-for-granted standards for a job well done. Indeed, professional identity and pride may be at stake. Paradoxically, the identified DH sector norms for stable, affordable, and invisible heat supply service provision may not necessarily motivate DH end-users /customers towards more sustainable heat-use behaviours: DH end-users in Denmark have come to expect these DH community heat supply provision as taken-for-granted societal goods, and the topics of space heating and thermal comfort are increasingly dissociated from consumption-related debates within public, and political realms. This DH case study shows how landscape, regime, and actor-level socio-technical trajectories interact, and it exemplifies actor-structure relationships in situations of regime stress. Perhaps it proves an exemplary case for exploring the lock-in mechanisms, inertia, restraints, and potentials of change-processes within also other societal domains and institutional realms.

Analyzing the Energy Usage of a Community and the Benefits of Energy Storage

Understanding the energy usage of a community is crucial for policymaking, energy planning, and achieving sustainable development. The advent of the smart grid has made it feasible to gather fine-grain energy usage data at large-scales, providing us with new opportunities to understand demand patterns at different spatial and temporal scales. In this paper, we conduct a large-scale empirical study of energy usage of 14,849 residential and commercial energy consumers from a small city in the United States. We conduct a wide ranging analysis of energy usage at multiple granularities—citywide, transformer-level, and individual home levels. In doing so, we demonstrate how city-wide smart meter datasets can answer a variety of questions on energy consumption, such as the impact of weather on energy usage. For example, we show that extreme weather events significantly increase energy usage, e.g., by 36% and 11.5% on hot summer and cold winter days, respectively. As another example, we show 19.2% of transformers in the grid get overloaded during peak load periods. Finally, we evaluate the impact of incorporating varying amounts of energy storage within the distribution grid and the impact such deployments will have on the peak demand patterns seen by the grid as well as the ability to reduce overloads seen by distribution transformers during peak periods.

Winter Carbon Dioxide Measurement in Honeybee Hives

Sensor technologies have sufficiently advanced to provide low-cost devices that can quantify carbon dioxide levels in honeybee hives with high temporal resolution and in a small enough package for hive deployment. Recent publications have shown that summer carbon dioxide levels vary throughout the day and night over ranges that typically exceed 5000 ppm. Such dramatic changes in a measurable parameter associated with bee physiology are likely to convey information about the colony health. In this work, we present data from four UK-based hives collected through the winter of 2022/2023, with a focus on seeing if carbon dioxide can indicate when colonies are at risk of failure. These hives have been fitted with two Sensirion SCD41 photoacoustic non-dispersive infrared (NDIR) carbon dioxide sensors, one in the queen excluder, at the top of the brood box, and one in the crown board, at the top of the hive. Hive scales have been used to monitor the hive mass, and internal and external temperature sensors have been included. Embedded accelerometers in the central frame of the brood box have been used to measure vibrations. Data showed that the high daily variation in carbon dioxide continued throughout the coldest days of winter, and the vibrational data suggested that daily fanning may be responsible for restoring lower carbon dioxide levels. The process of fanning will draw in colder air to the hive at a time when the bees should be using their energy to maintain the colony temperature. Monitoring carbon dioxide may provide feedback, prompting human intervention when the colony is close to collapse, and a better understanding may contribute to discussions on future hive design.

Drowning incidents in urban rivers: An underestimated issue with future challenges in need of an interdisciplinary database to characterise its epidemiology

In recent decades, the recreational use of urban rivers has become popular, and public access to riverbanks has improved. However, in the context of global warming, the risk of drowning in urban rivers may increase. The objective of this study is to examine drownings in the Rhone and Saone rivers in Lyon (France) and to identify risk factors, hot spots and high-risk moments using an environmental database.A total of 386 fatal and non-fatal drownings occurred in Lyon on the Rhone and Saone rivers between 2015 and 2021. The analyses identify that, universally, most drowning victims are men (68 %) and young adults (37 %). More drownings occur in the summer period (45 %). There are also hot spots near the city centre and in urban river parks. Three types of drownings are characterised by using principal component analysis (PCA) and hierarchical clustering on principal components (HCPC) methods. These groups are distinguished by hydrological and meteorological conditions, as well as by the seasonality and circumstances of the incident. The first group (G1) corresponds to drownings that occur on cold winter days, with high water flows and turbidity. The second group (G2) corresponds to drownings that resulted from bridge jumping in a festive context or a challenge between friends. These drownings occur on autumn days with interesting hydrological conditions (low flow and clear water). The last group (G3) groups together drownings that occurred while a victim is swimming in an unsupervised area. These drownings occur during the summer on very hot days. Finally, a multiple logistic regression method showed that the average daily outdoor temperature was positively correlated with the occurrence of drowning in Lyon (p < 0.05) and that daily rainfall was negatively correlated with the occurrence of drowning (p < 0.05).

Dynamic cabin model of an urban bus in real driving conditions

The transport sector is a key sector to reduce the emission reduction targets. The main auxiliary load, the HVAC system, contributes significantly to the energy consumption and affects the driving range in electric vehicles. Accurate and dynamic models are needed to optimize these systems in urban environments. This research presents a dynamic thermal model of a cabin, including a detailed 3D urban model, a consistent weighted stochastic kinematic model, a climate model accounting for all bus surfaces and environment, and a transient thermal model of the cabin. A validation was performed against dynamic experimental tests. The most demanding mode is for cooling, with a mean cooling demand of 105 kWh/100 km in a warm summer day. The heating demand on a cold winter day is around 22 kWh/100 km. The components analysis reveals that the occupancy contributes to 33–45 % of the cooling demand in summer and the solar components account for 20–42 %. Air changes contribute to 20 % of the heating demand in winter, and conduction, convection, and internal infrared components represent 40 % of the negative load, except for summer when they account for 10–20 % of the positive load. A sensitivity analysis has also been performed to quantify the impact of different strategies.

An Investigation towards Optimizing the Construction Materials and Configurations of Buildings for Improving Energy Efficiency and Consumption in Morocco

In this paper, a thermal performance assessment of traditional building constructions and configurations in various Moroccan climates is carried out. This research focuses on enhancing conventional energy efficiency of buildings by investigating the thermal behavior of single clay walls, double clay walls, simple brick walls, and double brick walls based on long-term meteorological data using TRNSYS software. The roof pitch, thermal comfort and discomfort index, and building energy consumption are considered while selecting buildings for each temperature zone. It is noticed that the double brick construction is more efficient in all climatic zones of Morocco. Thus, this material reduces the yearly energy requirement of building by 22% to 25% compared to the usual brick building. On the coldest winter days, a 30° south-facing roof raises the internal temperature by 2.5 °C compared to a horizontal roof. Temperature increases could reduce the air conditioning energy usage by 7% to 32% and overcooling hours by 12% to 21% in cities above 30° N. In addition, the findings are interesting enough to inspire individuals to implement the recommended construction design and study energy efficiency and thermal comfort in Moroccan buildings. Consequently, reducing energy consumption, mitigating climate change, and lowering greenhouse gas emissions.

Investigation of marine temperature changes across temporal and spatial Gradients: Providing a fundament for studies on the effects of warming on marine ecosystem function and biodiversity

A current critical issue in climate change studies is how temperature changes and shifts on different spatial and temporal scales can affect organisms in terms of trends, variability and frequency of extremes. In this paper, we analysed marine temperature data on different temporal and spatial scales. We related the sea surface temperature data from the Helgoland Roads Time Series, one of the most important and detailed long-term in situ marine ecological time series, to the Sylt Roads, North Sea, Germany, Europe, North Atlantic and Northern Hemisphere surface temperatures. All time series showed a distinct upwards shift in temperature in the late 1980s, early 1990s, with positive trends in overall for the period between 1962 and 2019 ranging from 1 to 2 °C over 57 years. We quantified changes in temperature variability by comparing the years before and after 1990, on both long-term and seasonal scales. At Helgoland and Sylt, an increase in the number of warmer days in summer and a decrease in extremely cold days in winter are the new characteristics of the temperature pattern after 1990; higher than expected temperatures now also occur earlier during the year. For these locations, we observed the highest trends overall, i.e. of around 0.3 °C/decade. The observed bimodal shape of the probability density functions, characterized by winter and summer modes, had become more heterogeneous, with the cold mode peak moving to higher values and the steepness to the peak increasing, which is a consequence of a decrease in extremely cold days. North Atlantic Oscillation (NAO) and Multidecadal Oscillation (AMO) large-scale phenomena had no significant correlations or, for the NAO, were limited to the winter season at the regional and local scales. The closest landmass (mainland Germany) temperature was highly correlated with the North Sea sites. Taken together, our results suggest that marine pelagic ecosystems and their species are subject to temperature shifts with similar patterns but with variations in magnitude at the different scales. Temperature is one of the main drivers of species diversity and distribution, and this manifests on different spatial and temporal scales depending on population growth, life stages, cycles and habitat. Accordingly, we here present the temperature changes on the appropriate spatio-temporal scales, and thus provide the suitable and useful fundament for studies on the effects of warming on marine ecosystem function and biodiversity.

Excess vibration and noise on gas turbine exhaust silencer

This particular gas turbine silencer experience excess vibration at a critical operating condition especially on a large powerplant applications. The vibrations seem to be more pronounced on cold winter days when the turbine load exceeds 110 MW. The excess vibration disappeared when it passed the critical operating condition to its maximum load 113 MW. The 18.5 Hz mode dominated the vibration spectrum. The mode consisted of a rocking motion of the entire silencer and a local deflection of the silencer walls. The experimental mode shapes corresponding to the 18.5 Hz will be discussed. A CFD (Computational Fluid Dynamics) analysis will be used to assess the flow-induced vibration problems.

Village Lunatics

Village Lunatics

Energy sustainability performance of a sliding-cover solar greenhouse: Captured energy management aspects

The utilization of solar energy as the unique source of green heat, during the cold period by solar greenhouses, is a crucial sustainability concern for off-season vegetables. This research effort serves to promote the modernization of the Solar Greenhouse industry, which is heavily practiced in northern countries. The heat collection and thermal performance of the harvested energy with the Water-cycling System (SWS) is analyzed and validated. The derivation of the heat storage/release experimental model was based on the diurnal water temperature cycle in the heat storage device. The energy cycle is based on the energy captured at the daytime and released at nighttime in the Sliding-cover Energy-saving solar Greenhouse (SEG), resulting in crop temperature surpassing a conventional Chinese Solar Greenhouse by 3℃. This is critical for a full production loss, at very low-temperature nights, appearing after sunny clear-sky cold winter days. The resulting energy model will be used by a Solar Greenhouse Designer program for the optimal design of Solar Greenhouses based on the locality climate and the targeted production facility to realize the smart specialization of climate zones. Further, a proactive, real-time energy management system will increase Production and Sustainability performance by maximizing energetic bio-efficiency.

Art-Kut! The Counter-Cultural and Feminist Spirituality of Shamanism in Postwar South Korean Art

Abstract On 17 January 1981, during a cold Winter Day at the height of an authoritarian military regime, a group of South Korean artists named “Baggat Misul [Outdoor Art]” gathered around a riverbank outside Seoul to interact with nature and called it “jayeon misul [nature art].” A young woman artist Yong-sin Suh performed an act the group called “a lark,” during which Suh alternated with two male artists in reading aloud sections of newspaper articles. These unhinged, free-spirited acts were inspired by the Korean folk theater tradition of pansori (traditional Korean musical opera), and kut (traditional Korean shamanistic exorcism). Korean shamanism by way of the mudang kut rituals has historically been a Korean indigenous belief intertwined with Buddhism and Taoism and stood as a counterforce to the mainstream nationalist neo-Confucian and imperial Christian conservative legacy that oppressed women and the nonconforming gender-neutral community in South Korea. The paper analyzes the Korean shamanistic elements that were utilized in performative, conceptual, and nature art practices by South Korean artists in the post-WWII period to the present, within the framework of the intersection of Korean feminism, art activism, and shamanistic spirituality.

A Novel Flexible Method for Optimal Operation Modeling of Multi-Carrier Energy Systems

This research suggests a new flexible method for the optimal operation of multi-carrier energy systems based on optimization techniques for different weather conditions and seasons. The results apply to different modes (a hot summer day, a cold winter day and a normal day). A new cost function from the operator’s point of view is suggested considering the constraints on consumable gas supply and electrical energy in the cold and hot seasons respectively. Furthermore, a novel algorithm is suggested that gives the economical values of energy carriers, final cost, and the percentage of the direct electrical energy supply and outside the hub. In this method, load data, related prices, constraints, and penalties are applied to the suggested model, and afterward hub optimization assists in finding the optimal operation and costs. MATLAB software is used to check the results and the simulation outputs confirming the effectiveness of the proposed method.

Electronic-physical model that determines thermal conductivity of walls made of various materials

The article analyzes data on creating an electronic-physical model designed to determine the thermal conductivity of walls from various loose or solid materials used in the agricultural sector and construction. At the end of 2022 and the beginning of 2023, during the abnormally cold winter days observed in the Republic of Uzbekistan, accidents were observed at many construction sites and in heating networks. In response to this, by the government's decision, practical work was carried out to cover buildings' outer part (facade) with special basalt material. The studies of one-dimensional heat transfer in a compound cylinder carried out in a stationary mode at a constant thermal conductivity of the material, are analyzed. In these studies, heat conduction equations were studied with the results of heat transfer simulations developed using the Ansys software. The electronic-physical model proposed in the article allows you to quickly and accurately measure the heat and thermal diffusivity of walls made of various materials. It will be possible to intelligently control the electronic-physical model using thermal sensors. The article contains detailed engineering calculations and illustrative materials. Internet data was analyzed, and specific conclusions were drawn. The prerequisites for the creation of an intelligent system for measuring the temperature and thermal conductivity of walls from various bulk materials are made in the work.

Cold winters drive consistent and spatially synchronous 8-year population cycles of cabbage stem flea beetle.

Population cycles have been observed in mammals as well as insects, but consistent population cycling has rarely been documented in agroecosystems and never for a beetle. We analysed the long-term population patterns of the cabbage stem flea beetle Psylliodes chrysocephala in winter oilseed rape over 50 years. Psylliodes chrysocephala larval density from 3045 winter oilseed rape fields in southern Sweden showed strong 8-year population cycles in regional mean density. Fluctuations in larval density were synchronous over time across five subregional populations. Subregional mean environmental variables explained 90.6% of the synchrony in P. chrysocephala populations at the 7-11year time-scale. The number of days below -10°C showed strong anti-phase coherence with larval densities in the 7-11year time-scale, such that more cold days resulted in low larval densities. High levels of the North Atlantic Oscillation weather system are coherent and anti-phase with cold weather in Scania, Sweden. At the field-scale, later crop planting date and more cold winter days were associated with decreased overwintering larval density. Warmer autumn temperatures, resulting in greater larval accumulated degree days early in the season, increased overwintering larval density. Despite variation in environmental conditions and crop management, 8-yearcycles persisted for cabbage stem flea beetle throughout the 50 years of data collection. Moran effects, influenced by the North Atlantic Oscillation weather patterns, are the primary drivers of this cycle and synchronicity. Insect pest data collected in commercial agriculture fields is an abundant source of long-term data. We show that an agricultural pest can have the same periodic population cycles observed in perennial and unmanaged ecosystems. This unexpected finding has implications for sustainable pest management in agriculture and shows the value of long-term pest monitoring projects as an additional source of time-series data to untangle the drivers of population cycles.

POTENTIAL BENEFITS OF INTRODUCING CANOE POLO IN THE SPORT SYSTEM OF WESTERN BALKAN COUNTRIES

The International Canoe Federation includes 10 forms of kayaking and canoeing and recognizes 4 additional disciplines. One of the most popular is canoe polo. Canoe polo is a team sport that belongs to the family of sports games. Two teams of five players each fight to score more goals, with a water polo ball, in a pool of specific dimensions. Canoe polo developed in parallel in three similar variants of the rules, as an alternative to paddling during windy and cold winter days. Canoe polo contains the largest number of different techniques in relation to all paddling sports, while ball handling is done with a mixture of water polo, handball, basketball, and volleyball techniques. Simultaneous handling of the ball, with an overview of the game and interfering with the opponent is a very demanding coordination activity that does not exist in paddling in nature with different obstacles, both in terms of content and dynamics. Today, canoe polo is played in about 40 countries. Wild and flat water kayak and canoe disciplines have existed in the countries of the Western Balkans outside the European Union for many years, while canoe polo activities, clubs and competitions do not exist at all. The introduction of canoe polo in the sports systems of the West Balkan countries outside of European Union can be used as a means to popularize canoeing, as well as to raise the quality of canoeists by applying situational and super-situational training methods. Very demanding activities during more diverting trainings, with a greater opportunity to compete, as well as with a longer and more meaningful competition calendar, can significantly improve the skills needed for kayaking and canoeing in all its manifestations. In addition, the economic effect of development through sports facilities, infrastructure and boats with protective equipment should not be neglected, which at some point may become the basis for the organization of domestic and international competitions.

Integrating a heat pump into a 4th generation district heating (4GDH) system – Two-mode configuration inputting operational data

The aim is to examine integrating a heat pump (HP) into a district heating (DH) system versus potential savings in the separate scenario. It takes into account all the properties of both DH system and a HP operation, and gives the understanding of temperature, pressure and enthalpy of refrigerant at each cycle point. Contribution to the pool of knowledge is considering a novel configuration, which allows to get rid of a heat exchanger between the water-source HP and the network. Scenarios of (i) separate operation of a HP, and (ii) integrating it into a DH system and inputting design data only, or (iii) utilizing operational data have been analyzed. Multiple thermal simulations have been performed. We also allow traditional coverage of heat demand with the help of a supply line of high-temperature DH (HTDH), thus elaborated what happens when the outdoor air temperature drops below lower threshold. Hence, the model identifies two stages of operating a HP integrated into a DH system. Starting from it, the temperature of the supply water should be 50 °C and above, so it is more effective to use supply water directly until the outdoor temperature rises again. This outdoor temperature implies change of operational mode, which leads to the following results. On cold winter days, the available amount of heat is lower than the energy consumption, therefore, energy from a supply line of HTDH is utilized, which gives overall energy saving effect of about 14 %. Mass flow rates through the configuration suggested are identical during moderate-cold fall and spring days, since the control logic is established with the help of variation of supply temperature only. Single HP has the lowest efficiency because of high temperatures needed: with a nominal temperature difference of 25 °C, the coefficient of performance (COP) rises to 5.0 only. At the break-even point, HP in each configuration has COP ranging between 3.51 and 4.43, while the rest of the time COP is just above 2. In different cases, the lowest threshold of HP's performance is 2.4, 2.6, and 2.89, respectively. The DH-assisted scenario, where peak energy demand was covered by DH system directly, clearly outperformed separate installation, where a HP was the only thing responsible to provide the necessary supply temperatures. For this case, lower COP stipulates less energy is supplied from the DH system, and therefore a lower share of consumption is supplied directly from supply line, which decreases the overall seasonal COP. Scenario (iii) of inputting DH operational data has the highest seasonal COPs, reasoned to higher than design return temperatures. Given the low performance of a HP raising water temperature to 55 °C (the lowest threshold acceptable in winter) a single HP with no backup capacity accounts for 23 % more energy use. Supported by a coal-fired combined heat-and-power plant, distribution of primary energy consumption is more favorable, i.e. coal-fired generation covers the peak. The positive effect is expanded by converting a part of heat demand from HP operation to cheaper HTDH operation.

Optimisation of passive solar systems seasonal operation in conditions of central Europe

The paper deals with optimisation of passive solar systems installed on family and office buildings in central Europe locations. In these territories, in contrast to more southern countries, it is not typical to utilize passive solar systems on public or private buildings. Although these systems can significantly influence thermal comfort inside the buildings, many controversions and myths reduce wider utilisation. It could be expected, that new European legislative tending to common energy savings will cause also wider usage of these systems. In contrast of classic countries utilizing passive solar systems, the benefits can be expected either in hot season or in cold season. If we focus on systems that can supplement existing buildings – roller blinds and slats, significant energy and economy benefits can be easily reached. These systems can either decrease or avoid overheating during hot summer days or to limit thermal loses in cold winter days and nights. This paper compares various roller blind and slat systems installed on office building and family house. Exact measurements explains the influence on thermal gains, thermal loses and thermal comfort in particular storeys during constituent seasons. The main results of these experiments and calculations are principles of operational charts for particular locations in the buildings leading to provable energy savings and economy profits. The measurements also serve as verification of computer simulations.

Energy Flexibility Comparison of Different Control Strategies for Zones with Radiant Floor Systems

Radiant floor systems offer significant potential for studying and developing energy flexibility strategies for buildings and their interaction with smart grids. Efficient design and operation of such systems require several critical decisions on design and control variables to maintain comfortable thermal conditions in the space and floor surface temperatures within the recommended range. This study presents a comparison of different control strategies to activate energy flexibility for zones with radiant floor heating systems. The focus of this study is on the zones with radiant floor systems for which the hydronic pipes are located deep in the concrete and therefore, there is a significant thermal lag. A perimeter zone test room equipped with a hydronic radiant floor system in an environmental chamber is used as to validate the modelling methodology. Considering a typical cloudy and cold winter day, three different control strategies for radiant heating were studied based on controlling the zone air temperature, floor surface temperature, and the operative temperature. Then considering morning and evening peak demand periods, the downward and upward energy flexibility are quantified and compared with each other for the different control strategies. It is observed that for the same 2 °C increase or decrease in the setpoint, the control strategy based on the zone air temperature results in the higher flexibility for both downward and upward scenarios compared with the floor surface and operative temperature controls. The effect of increasing window to wall ratio (WWR) is also investigated. Then, also the effect of solar gains on a sunny day on energy flexibility is studied. No significant difference in the upward and downward flexibility is observed. However, the hours of zero heating load are significantly increased due to the contribution from the solar gains.