Hot Summer Days Research Articles

Comparative Study of Different Crassulaceae Species for Their Potential Use as Plant Covers to Improve Thermal Performance of Green Roofs

The presence of green roofs in urban areas improves the energy efficiency of buildings; contributes to the capture of CO2, decreasing pollution; and improves the appearance of cities, increasing their sustainability. Additionally, green roofs must include plant species with low requirements and maintenance, and thus, succulent species could be useful in Mediterranean semi-arid regions. In this work, the thermal inertia and the effect of different succulent species as thermal barriers on mitigating the increase in temperature inside experimental compartments were studied in comparison to conventional covers used in the Spanish Mediterranean for a whole year. In general, green covers were more efficient than conventional ones for controlling temperature. Thus, temperatures under green covers were up to 8 °C lower than conventional covers and 3–5 °C lower than the ambient temperature at noon on summer days. Furthermore, significant differences were found between green covers. Thus, despite having high thermal inertia, Aptenia cordifolia showed the worst temperature records, while Aeonium arboreum was the most efficient at mitigating temperature changes both on cold winter nights and hot summer days—even better than Sedum spp., a usual succulent used commercially. Our results demonstrate that succulent species are efficient materials to use as green covers to improve thermal conditions in buildings in Mediterranean cities. This also suggests that the mixture of succulent species (i.e., not only made of Sedum spp.) with different colors and textures could beautify green roofs without compromising their energy efficiency.

Prediction of mean radiant temperature distribution around a building in hot summer days using optimized multilayer neural network model

Urban warming has become increasingly serious in recent years. Especially in the case of hot summer days (with maximum daily temperature greater than 30°C), the number of people suffering from heat stroke increases every year. To mitigate urban warming and adapt to it, many researchers have focused on improving outdoor thermal comfort. The mean radiant temperature (MRT) is one of the most important variables affecting human thermal comfort in outdoor urban spaces; however, the process of MRT calculation requires a lot of computing power and time. The main objective of this study is the optimization of the back propagation and genetic algorithms on the basis of a multilayer neural network (MLNN), as an alternative to the time-consuming and computationally intensive process for quick MRT prediction. In this research work, a neural network was trained using the relevant weather-related and building morphology-related parameters that may affect the MRT from 2014-2018 as training parameters, the distributions of MRT around buildings in hot summer days of 2019 were predicted using an optimized neural network model. The results show that the mean absolute percentage error (MAPE) and root-mean-square error (RMSE) of the optimized model were lower than 1% and 1°C.

Green roofs on buildings – different view on its construction solution

The need of green in cities or the increase of its ratio is very requested in this time of global warming. Buildings in combination with traffic cause so called urban heat islands. The high surface temperature on the facade of buildings causes the increase of surrounding air temperature in the towns. This situation creates the discomfort for their citizens. Also we have to consider with higher operating costs for cooling systems in buildings. The solution how to help is the using of green architecture for each new building but also for reconstructed existing buildings. Green roofs and walls are not new and we have different construction solutions. But this article brings different view on the construction solution of green roofs. It should be the solution that can decrease the heat load of building. This proposed solution allows using the area of flat roof for installation of air handling units and their ducts. The design of space on the flat roof overarched by greens creates better conditions for the operations of air handling units during the hot summer days when the fresh air is sucked from the shaded space that is not overheated by solar radiation.

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.

The impact of the exterior green wall on the summer regime in the building – energy simulation

The analysis is based on the results of computer simulation by using DesignBUILDER software. In the analysis is the multi dwelling house assessed. There are standard building constructions used like as the brick wall with polystyrene thermal insulation, Windows with plastic frame and double glazing and the flat roof with thermal insulation from polystyrene without the gravel layer. In this thermal simulation is considered with so called green walls, that are localized at eastern, southern, and western facade of the building. The light steel frame construction with the net from thin steel ropes creates the area for the climbing plants like a ivy. The function of the used green walls with climbing plants is to shade the external walls of the building in order to reduce the impact of solar radiation on the building facade during the hot summer days. We can these green walls in combination with external blinds consider like a effectively solution in order to reduce the energy consumption for cooling system in the building. By the way the used green walls help to reduce the air temperature surrounding the buildings and so they create the better town climate for their citizens.

The Great Resignation II

The Great Resignation II

Going performative in education – the artistry of teaching

It is a hot summer day in 1979. As a student teacher (English/German studies) at the Carl von Ossietzky University of Oldenburg at the time, I am taking part in a seminar on the subject of alternative schools. The lecturer suggests leaving the stuffy room and holding the lecture under a tree by the Haare, a nearby river.

Between vision and action: the predicted effects of co-designed green infrastructure solutions on environmental burdens

AbstractGreen Infrastructure (GI) is gaining wide recognition in cooperative research projects seeking to find solutions for climate adaptation in urbanized areas. However, the potential effects of co-produced GI plans and the underlying preparation process are rarely evaluated. To bridge this gap, the aim of this article is to examine what works in addressing environmental burdens in the urban neighborhood of Dortmund Marten, Germany. As part of a larger transdisciplinary process, selective GI measures were delineated in the case study area through a cooperative workshop between scientists and urban planners. Workshop ideas were incorporated into a mitigative scenario considering a hot summer day to quantify the effects of the derived GI measures on thermal comfort and particulate matter dispersion (PM10 and PM2.5). To evaluate the experiences of the science-practice collaboration, the viewpoints of researchers and urban planners on learning effects, knowledge integration, and GI planning were summarized and compared via an online survey. The results indicate that the proposed GI measures could reduce physiological equivalent temperature (PET) by 25 °C. At the same time, additional roadside trees could increase PM10 concentrations by up to 36 µg/m3 due to wind blocking effects. Reflections on the science-practice workshop show that learning effects were higher for the participating researchers than for planning practitioners, while the integration of individual expertise during the workshop was more difficult for academics. These findings point to the importance of continuous reflections on individual understandings in cooperating stakeholder groups and the value of the evaluation of outcomes in transdisciplinary GI planning.

The choices we make

I remember walking through the factory on cold mornings and noticing that the fume in the air would seem to hang more heavily. The shutter doors would be closed, reducing drafts and exposure to a cold wind, but also reducing natural ventilation. On hot days in summer, the opposite was true. Doors kept open to capture every passing breeze and workers stripped down to the minimum of clothing, potentially reducing their protection. Temperature changes can be uncomfortable, sometimes even unbearable. They force us to act, and sometimes to take actions that provide short-term relief at the cost of potential long-term harm. This winter, with gas prices soaring to unprecedented levels, there has been a clamour in certain quarters to look again at shale gas, as well as rumours of political interference in the approval process of North Sea oil and gas fields. With tensions in Eastern Europe looking set to...

Lighting a Reliable Path to 100% Clean Electricity: Evolving Resource Adequacy Practices for a Decarbonizing Grid

It is the year 2045 in the carbon-neutral southwestern United States. While summer heatwaves have increased in frequency and intensity because of climate change, the region’s abundant solar generation produces tremendous amounts of low-cost energy on hot summer days. This energy not only serves daytime loads but it also charges an enormous fleet of batteries that, aided by wind and geothermal power, discharge overnight to effectively eliminate summertime electric reliability concerns.

Home is where the heat is: Thermoregulation of European bats inhabiting artificial roosts and the threat of heat waves

Abstract Anthropogenic land use changes, such as deforestation and commercial forestry, have substantially reduced natural roost sites for European bats. A common conservation solution is to provide artificial roosts (i.e. bat boxes), but there are concerns that these can become hotter than natural roosts in summer and could be death traps during heat waves. Nevertheless, females of several bat species form maternity colonies in these boxes, thus occupying hotter and more humid microclimates than solitarily roosting males. We tested if cooling efficiency and heat tolerance differ between sexes in European bats, and estimated the evaporative water requirements for bats living in bat boxes during hot summer days. We used indirect calorimetry and thermometry to quantify thermoregulation at high air temperatures (Ta) in four species of verspitilionid bats that regularly occupy artificial roosts. We measured resting metabolic heat production, evaporative water loss rates (EWL) and body temperature (Tb) at Ta between 28°C and 48°C during summer. We predicted that females have higher evaporative cooling efficiency (evaporative heat loss/metabolic heat production) than males, allowing them to reach their heat tolerance limit at higher Ta. We found no sex differences in maximum evaporative cooling efficiency, maximum Tb, and maximum Ta tolerated. However, the patterns of increasing EWL with Ta differed between sexes. Females tolerated higher Ta before increasing EWL than males and then rapidly increased EWL to higher values than males at the maximum Ta tolerated. These sex differences in heat dissipation strategies may reflect varying ecological and physiological constraints associated with different summer roosting habits. Synthesis and applications. Our study revealed that some small European bat species are already at risk of succumbing to lethal dehydration during present‐day heat waves, with daytime evaporative water requirements equivalent to ~30% of body mass in sun‐exposed boxes. For conservation managers working with common European bat species, particularly those in monoculture forests with woodcrete bat‐boxes, our physiologically informed recommendations include positioning boxes in diverse locations varying in aspect and sun exposure. This will ensure thermal heterogeneity of roost sites and provide a wide gradient of microclimate conditions, allowing for roost switching when necessary.

Influence of view factors on intra-urban air temperature and thermal comfort variability in a temperate city

Urban geometry is known to be one of the major factors in explaining the intra-urban temperature variations. A commonly used indicator to describe the urban geometry is the sky view factor. However, the existing studies have shown that the relationship between SVF and urban temperature is quite contradictory. This suggests that a single SVF cannot accurately quantify the urban geometry. For comparison, we here propose to use view factors, including sky, building and tree view factors (SVF, BVF, and TVF, respectively), to accurately quantify the three-dimensional urban geometry. Based on microclimate measurements conducted in Beijing Olympic Park and its surrounding urban environment in Beijing, China, the impact of view factors on intra-urban air temperature and thermal comfort was evaluated. Measurements were conducted along a selected path during hot summer days with clear skies and light winds by mobile traverses. The obtained results showed that SVF was positively correlated with air temperature during the day but negatively correlated with air temperature at night. BVF mainly played a warming role in both daytime and nighttime. Especially at night, BVF was the main geometric warming factor. TVF had a significant cooling effect during the day but did not have a negative effect at night due to reduced SVF. There was a strong point-to-point correlation between SVF and outdoor thermal comfort in the daytime. The mean differences in Mean Radiant Temperature and Physiologically Equivalent Temperature between shaded and unshaded sites were 12.0 °C and 6.8 °C, respectively, which suggested that providing effective shading is extremely important for improving outdoor daytime thermal comfort.

My Journey Through a Kidney Transplant Procedure.

My Journey Through a Kidney Transplant Procedure James Moran Polycystic Kidney Disease is hereditary. My grandmother died at home before dialysis was readily available. My mother, uncle, and great aunt all had dialysis treatments for extended periods of time and eventually died. My uncle was most fortunate in that he had a heart attack while on dialysis. My mother and great aunt suffered through the disease before it consumed them. The magic age for adult onset PKD requiring dialysis is in the early fifties. First diagnosed at age 25, I watched my creatinine levels increase over the years and knew what awaited me. I was 52 when my nephrologist said it was time for me to have the surgical procedure to attach a vein to an artery in my left arm. This arteriovenous fistula is the access point for dialysis. He said that I would probably need dialysis within about three months. It was about one year more before I really needed it. Even though it was an eventuality we had expected for over 25 years, my wife said: “I thought we had more time.” I considered myself fortunate to have dialysis available and so close. The center was about ten minutes from my house. The 5:30 AM appointment time was not my first choice, but it did enable me to continue working and still have evenings at home with my family. The initial few months are called the “honeymoon” period. Things were going well, I was tolerating the treatments, and I felt better. Why would I need a transplant? I attended a pre-transplant session at a hospital at my wife’s insistence. I really had reservations about the process. Except for the out-patient AV fistula surgery, I had not been “under the knife” and never had a hospital stay. A pre-transplant session at a different hospital was even more graphic and made me less enthusiastic. Eventually, dialysis became more difficult and I felt more fatigued. It was more disruptive and vacations always created scheduling issues. Both hospitals as well as the dialysis team, encouraged me to look for a live donor. They suggested that I contact family members and friends to tell them I was in need of a kidney donor. My oldest son who was 21 at the time offered immediately without being asked. Personally, I felt reluctant to put someone else at risk for me even though they assured me that the donor would remain safe and my outcome would be better. I reluctantly placed myself on the transplant list and received dialysis for about four years before a cadaver kidney became available. The story of the call from the transplant clinic was interesting. My transplant surgeon had told me that I would need a bilateral nephrectomy because my polycystic kidneys were large and infected. He said that they needed to be removed before the transplant, but the removal should be delayed until I was closer to the top of the transplant list as it would add extra stress on my body. After about three years on dialysis, I received my first call. I declined the kidney and scheduled the nephrectomy. This surgery was difficult and I was in a lot of pain. The following year was brutal while I waited for the next call. Without my native kidneys, I was no longer producing urine and I had severe limitations on fluid intake. This was most unbearable during hot summer days. The long wait between the first and second calls was exacerbated by a nearby transplant center being closed as people transferred their wait time to the center on which I was listed. In the ideal scenario, I would have received a call soon after the nephrectomy had healed. The second call came while I was on a Boy Scout camping trip. I had been involved in Boy Scouts for 25 years in varying capacities but many as Scout-master and frequently camping. I probably spent several hundred nights in a tent. On this trip, I had no cell signal inside the camp. My wife received the call at home and, after failing to reach me, drove to our camp and walked...

Orange Soda

Orange Soda Leo Coffey (bio) Dan is fifteen and almost a foot taller than me. Even though I'm only six years younger, he thinks it's funny to call me a kid. Our daddies cut grass together, so in the summer we spend a lot of time with each other. We like to shoot BB guns at the neighbor's cats and swim in the creek behind my house. Sometimes we sneak into my daddy's closet [End Page 69] and hold the real heavy guns while we look in the mirror, but I always get nervous doing that. I think because my grandpa once told me about how he watched a man get his head blown clean off in Vietnam. I never could get the image of that man's neck spewing blood like a fountain out of my head. Sometimes when it storms, I dream about that man walking up behind me. I never fail to wake up just before I turn around, but I always know that it is him. It is one of those hot summer days in Ellenboro, North Carolina, like strip your clothes off as soon as you walk out the door hot. There seems to be no end in sight to our friendship as Dan and I make our way down US-74 on foot. We don't talk much; we just walk with our T-shirts pulled up over our heads to let some air onto our skin. My belly button pokes out like a budded flower. When we make it to the KwikStop, the parking lot is empty minus an old white Honda Accord parked by the air pump. I can hear The Lake playing a tribute to Whitney Houston from the speakers, the soft tune of her asking, "Where do broken hearts go? Can they find their way home?" She died earlier this week, and everybody's momma was torn up about it. I sit outside on the bench to the left of the door while Dan goes inside. Dan wants to get a soda before we walk to his house a half-mile further. He doesn't tell me that he doesn't have any money. There are piles of ash sitting along the bench and I lean down and blow them off one at a time, watching the wind redeposit every particle onto the asphalt. After a few minutes, the door creaks open and Dan walks out. He sits down next to me and lifts his shirt to reveal a bulged can shoved deep into his pants pocket. He cracks open the aluminum and takes a long sip like he hasn't ever had anything to drink in his life. His nose scrunches up as the [End Page 70] liquid tunnels down his throat. He swallows hard and takes a deep breath to make room in his mouth for words. "Damn! That's good shit," he says. He places the can on the pavement by his feet and removes a Snickers from his pocket. Sweat falls like shadows on the floor from the black hair that curtains his forehead. He devours the candy bar in a few bites and tosses the wrapper over his shoulder. It falls to the ground like a leaf. "You ever stolen anything, Clint?" Dan asks. I say no. "Why not? Think you're too good for it?" I say no. He takes a blade out of his pocket with his free hand and unfolds my fingers to place its metal weight into mine. My eyes grow wide with surprise. "I want you to go in there and steal something. Anything you want. And if that lady behind the counter says anything, you flash her this knife," he says. I say I can't do that. I tell him it's wrong. "What's more wrong-going hungry and dying of thirst? Or stealing?" I say nothing. "Fine. Well, you ain't having none of my orange soda, and you can turn around and go on home, too." It is hot as piss outside. I can feel myself growing more fatigued the longer we sit in the heat. I don't want to...

Evaluating the Use of Waste Materials in Building Envelopes for Energy Efficiency: A Theoretical and Empirical Study

With the increasing interest in energy-efficient building design, building energy simulation programs are increasingly employed in the design process to help architects and engineers decide which design alternatives save energy more. This research is an empirical and analytical study using a ready-made software package to evaluate the energy efficiency performance of building envelopes using recycled waste material. These methods used available environmental alternatives material in the experiment. To verify the results, two practical cases are tested. Validation is examined by comparing experimentally measured data and computational simulation data during the same summer period time. Real cases with small-scale actual rooms that were used to generate data to validate numerical models. The focus of this study is to compare the experimental measured thermal behavior of traditional and waste materials in residential buildings with simulation results. This comparison allows determining the effect of using waste material in southern walls of a residential building at an indoor temperature during hot summer days, in which the measurements took place during June and July. Meanwhile, the results indicated that the indoor temperature of real models was higher than the temperature of simulation models with about 3°C to 6 °C at measuring time (six summer days). This increase is about o 5.4% to 11.8%. The findings also revealed that the use of waste material in the southern wall of a residential building could decrease the indoor temperature by about 0.2 - 3°C degree compared with the traditional material at the same wall. It means that waste materials in southern walls could decrease 0.9% to 4.1% of indoor temperature compared with traditional materials. This study found that the analytical and empirical small-scale models could contribute to determining the usage of waste material at southern walls of residential buildings. Also, the comparison of the results indicates that Design-Builder can predict indoor temperature to achieve thermal comfort with good accuracy and it can be used by researchers and designers to evaluate the thermal performance of buildings.

Aerogel‐Functionalized Thermoplastic Polyurethane as Waterproof, Breathable Freestanding Films and Coatings for Passive Daytime Radiative Cooling

Passive daytime radiative cooling (PDRC) is an emerging sustainable technology that can spontaneously radiate heat to outer space through an atmospheric transparency window to achieve self‐cooling. PDRC has attracted considerable attention and shows great potential for personal thermal management (PTM). However, PDRC polymers are limited to polyethylene, polyvinylidene fluoride, and their derivatives. In this study, a series of polymer films based on thermoplastic polyurethane (TPU) and their composite films with silica aerogels (aerogel‐functionalized TPU (AFTPU)) are prepared using a simple and scalable non‐solvent‐phase‐separation strategy. The TPU and AFTPU films are freestanding, mechanically strong, show high solar reflection up to 94%, and emit strongly in the atmospheric transparency window, thereby achieving subambient cooling of 10.0 and 7.7 °C on a hot summer day for the TPU and AFTPU film (10 wt%), respectively. The AFTPU films can be used as waterproof and moisture permeable coatings for traditional textiles, such as cotton, polyester, and nylon, and the highest temperature drop of 17.6 °C is achieved with respect to pristine nylon fabric, in which both the cooling performance and waterproof properties are highly desirable for the PTM applications. This study opens up a promising route for designing common polymers for highly efficient PDRC.

Artificial Neural Network Modeling for Predicting and Evaluating the Mean Radiant Temperature around Buildings on Hot Summer Days

In recent years, the phenomenon of urban warming has become increasingly serious, and with the number of urban residents increasing, the risk of heatstroke in extreme weather has become higher than ever. In order to mitigate urban warming and adapt to it, many researchers have been paying increasing attention to outdoor thermal comfort. The mean radiant temperature (MRT) is one of the most important variables affecting human thermal comfort in outdoor urban spaces. The purpose of this paper is to predict the distribution of MRT around buildings based on a commonly used multilayer neural network (MLNN) that is optimized by genetic algorithms (GA) and backpropagation (BP) algorithms. Weather data from 2014 to 2018 together with the related indexes of the grid were selected as the input parameters for neural network training, and the distribution of the MRT around buildings in 2019 was predicted. This study obtained very high prediction accuracy, which can be combined with sensitivity analysis methods to analyze the important input parameters affecting the MRT on hot summer days (the days with the highest air temperature over 30 °C). This has significant implications for the optimization strategies for future building and urban designers to improve the thermal conditions around buildings.

Dynamic effects of frequent step changes in outdoor microclimate environments on thermal sensation and dissatisfaction of pedestrian during summer

• Subjects’ dynamic thermal responses to frequent microclimatic step changes are investigated. • Comparison between surveyed dynamic thermal sensation and predicted sensation is made. • Equivalent UTCI* based on SWI and frequent step change effectiveness is proposed. • Applicability of UTCI* in evaluating thermal sensations under frequent step changes is evaluated. • Impacts of frequent microclimatic step changes on thermal dissatisfaction in summer are revealed. Humans engaging in outside activities are more likely to be exposed to frequent spatiotemporal step changes in outdoor thermal conditions, as opposed to constant thermal conditions staying indoors. Understanding pedestrians’ thermal reactions to such dynamic thermal settings is helpful for enhancing outdoor thermal comfort by providing spatiotemporal variations in thermal conditions. In this study, 48 subjects were tested about their thermal perceptions while being exposed alternately to direct sunlight and shade at different defined frequencies, in a series of 45 min experiment period. The experiments were designed to create step changes in microclimate environments. The study was carried out from May to July in a university campus in Hong Kong with subtropical weather conditions. Results show that subjective thermal perceptions varied with alternating exposure to sunlight and shade at different frequencies. UTCI was modified to an equivalent UTCI* for evaluating thermal environments with frequent step changes by taking into account impacts of mixed changes in sun and wind conditions, alternating frequency and expectation on thermal perceptions. With a higher alternating frequency, there was reduced thermal dissatisfaction with hot summer days and a lower comfort requirement for shade, as well as the upper limit of acceptable UTCI* approaching 43.7 °C.

Modeling the Shading Effect of Vancouver’s Urban Tree Canopy in Relation to Neighborhood Variations

Background: Cities consume a disproportionate amount of energy for internal temperature regulation. Being able to reduce cities’ cooling load on hot summer days can decrease energy consumption while improving occupants’ thermal comfort. The urban canopy is an effective shading agent, adding cooling benefits to existing buildings and streets while providing other ecological and physiological values. Yet the building and street shading dynamic is a highly complex system that involves micro-level building components and macro-level variables. Introducing urban canopy to such a complex system creates another challenge, as urban canopy variables can also interact with buildings at both micro- and macro-levels. In order to accurately represent the urban canopy shading effect, it is necessary to account for the interactions among buildings, streets, and urban canopies. Methods: This study simulates the shading effect of urban canopy measured by aerial laser scanning (ALS) in the City of Vancouver, Canada, through the integration of a Radiance daylight simulation engine and geographic information system (GIS) data. All trees detected by ALS were included in the analysis. Results: The results indicate that street surfaces receive more solar irradiance reduction than building roofs and façades (i.e., exterior walls). Neighborhoods with less density and lower buildings were shaded noticeably better than areas with higher density and taller buildings. Among Vancouver’s 22 neighborhoods, 2 neighborhoods, Kitsilano and the West End, demonstrated a promising sign where both building density/height and urban canopies are maintained. There was evidence of high canopy shading and high-density urban morphologies. Conclusion: Overall, this work provided an authentic canopy assessment from single building to city scale, creating opportunities to investigate intracity urban canopy variations, equality, and the balance between urban greening and urban densification.

Evaluation of dietary betaine on post-thawed semen quality in mature bulls during summer heat stress.

Heat stress (HS) has caused relative hypoxia, oxidative stress and high level of homocysteine, which contributes significantly to fertility failures in bulls. The aim of present study was to evaluate the role of dietary betaine (BET) in improving dual purpose Simmental (Fleckvieh) post-thawed semen quality especially during the hottest summer days. A total number of 16 mature bulls were randomly assigned to three equal groups including: 1) Control condition (without betaine), 2) BET1: 57.00 mg of betaine kg-1 per day and 3) BET2: 114 mg of betaine kg-1 per day, through daily intakes for 90 days in summer. Plasma levels of homocysteine, seminal plasma antioxidants levels and sperm parameters such as DNA fragmentation, chromatin integrity, motility, viability, morphology and membrane integrity were evaluated. Under maximal HS, serum homocysteine concentrations were reached 16.67 ± 0.09 µmol L-1. Dietary betaine supplementation influenced DNA fragmentation of sperm and was higher in the control group compared to BET2 group. There were significant decreases in seminal plasma superoxide dismutase (SOD), glutathione peroxidase (GPx) activity and sperm viability and motility in bulls treated with betaine. The activity of GPx and SOD in the control group was increased up to 0.08 ± 0.00 U mg-1 protein and 0.52 ± 0.01 U mg-1 protein in seminal plasma. There were no significant differences between groups in the percentage of swollen spermatozoa, membrane integrity, sperm morphology, abnormal head morphology and percentage of spermatozoa stained with aniline blue. In conclusion, BET supplements improved semen parameters in sperm motility, sperm viability and influenced DNA fragmentation during HS with reduction in serum homocysteine concentrations.