Conditioned atria in the built environment - A possible solution for unsustainable urbanization and climate change in Nordic climates?

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Master’s thesis

Two years

Environmental science

Conditioned atria in the built environment - A possible solution for unsustainable urbanization and climate change in Nordic climates?

Lucas Cupello de Vasconcellos

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MID SWEDEN UNIVERSITY

Ecotechnology and Sustainable Building Engineering Examiner: Anders Jonsson, anders.jonsson@miun.se Supervisor: Itai Danielski, itai.danielski@miun.se

Author: Lucas Cupello de Vasconcellos, lude1800@student.miun.se

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Acknowledgments

First, I would like to thank my family for the constant support, although the distance and “saudade” you have encouraged me from the start to do what I thought was right for me.

I thank my coordinator Itai Danielski for the patience and guidance during this process and contributing not only on this step of my career but also with advice on being a better person.

My friends Chris, Griet and Åsa, I thank you for the inspiration for pursuing this thesis, which started with our discussions and work with the “Green Room” idea.

Last, I would like to thank the people working at Skanska, Östersund Kommun, Naturskolan of Umeå and Nynäshamns Kommuns, and Östersund International English School, who gave their time to help with the necessary materials and insightful discussions for the progress of this research.

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“So you children of the world, listen to what I say

If you want a better place to live in, spread the word today

Show the world that love is still alive, you must be brave

Or you children of today are children of the grave, yeah!”

Black Sabbath, Album: Master of Reality

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Abstract

With ever increasing urbanization and the degradation of the natural environment there is an urgent need for reinvention of our built environment that not only fulfill practical or economic needs, but to satisfy the current broader understanding of sustainability which accounts for integration of social, environmental and economic spheres. The innovative use of transitional spaces like the atrium dates back to the Roman civilization but their potential improvements to our built environment have never been as relevant as before, in face of the need to broader the effort of tackling climate change in all aspects of modern society. The use of conditioned atria explores an integrated problem-solving approach, by lowering energy demands and giving new life for spaces that would normally be inhabitable during the colder seasons of the year in Nordic climates.

In temperate climates, for a well-designed atrium, i.e., with a proper geometry and enough glazing area, the understanding surrounding the possible energy gains during the colder seasons are well established. And by providing a sheltered space, the atrium can serve as a place of social interaction, which has been found to influence occupant’s creativity through network dynamics and have positive effects on well-being by creating a sense of belonging. But little is known about the environmental implications of this kind of projects. While thermal properties, energy demands variations, cooling, heating, shading, and ventilations techniques are well explored, the research in the field still is behind in understanding what are the implications to the environment and if they can be credit as benefits when compared to other options for improvements of the built environment.

The aim of the research is to explore the differences in final energy consumption and environmental impact of the construction materials related to the atrium alternative and a business-as-usual and evaluate how to improve thermal properties of old buildings that require renovations to fit thermal efficiency standards and comfort in operational conditions while reducing the overall impact of the projects. The so-called business-as-usual approach, for this research, is the refurbishment or replacement of weather damaged walls of the building, in this case the walls adjacent to internal gardens in the building. And the proposed better alternative is the construction of conditioned atria in these gardens, partially glazed roofs which permits the creation of an enclosed space connected to the outside environment by this glazed area. In this alternative the old and damaged walls can be maintained while not compromising thermal efficiency and comfort in the building.

Results show that for the low-rise atrium most of the parameters related to the final energy demands and environmental impacts of the atrium construction materials are proportional and linear to the increase of the glazing area size. When compared to simply renovating old structures, the atrium alternative can promote a decrease in thermal losses by transmission and increase in incident solar radiation through the glazed area depending on the atrium dimensions and glazing area size. And although cooling, heating, electrical and ventilation demands are raised for the overall demand of the building the construction of an atrium bears less environmental impact than renovating old structures damaged by weather.

Key Words

Conditioned atrium, built environment, final energy consumption, energy efficiency, indoor gardens, green spaces, Internationella Engelska Skolan Östersund, International English School Östersund, temperate climates, Nordic climates, weather damage, refurbishment, repair, impact, environmental impact.

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1. Introduction

The architectural concept of atria dates back originally to the Roman civilization. A recurrent configuration of a Roman house among the wealthiest members of its society would include from the main outside entrance, an inner courtyard followed by an atrium, a sheltered shared open space serving as the entrance of the quarters, and through which the rooms were all connected. Serving as the main hall of the house, the atrium walls would be ornated with colourful drawings, and the space, filled with statues and pottery displaying the wealth of the residents. Used for social gatherings, the atrium also fulfilled other practical purposes aimed to improve domestic quality of life. The atrium was connected to the external environment via a centre opening on the roof, the compluvium, where below was located the impluvium (Roman domestic architecture, 2015), a shallow pool which could occasionally gather rainwater for domestic use. The compluvium also allowed natural sunlight to fill the room and the water in the impluvium acted as a mirror reflecting incident light and absorbing solar radiation which improved thermal comfort.

The modern atrium is characterized by the use of glass and iron to create the same sheltered open space but now different from the Roman designs, the climate can be fully regulated. It is first example in western world was built in 1806, at the picture gallery of the Attingham Park country house at the Shropshire county in England.

Designed by the regency architect John Nash (18 January 1752 – 13 May 1835), this example was the first case of the use of cast iron and small glass tiles on a roof with the intention to provide lighting to a room that had no windows but needed good lighting for the exposition. (Attingham Re-discovered Goes Through the Roof, 2016).

Although more “advanced” technologicaly the Roman concept remains, the modern atrium has been used to create a socially stimulating environment, to provide sheltered space for controlling external weather and temperatures variations and to increase the reach of natural daylight into the interior of larger buildings allowing the nurturing of indoor gardens and reducing electricity consumption (Hung and Chow, 2001).

The development of modern atrium design was closely related to the improvements of technologies that allowed the artificial control of the climate in closed spaces. In the early 19th century, the development in the first greenhouses, passive solar storage techniques, shading methods, insulation shutters and blinds, and auxiliary heating systems (Hung and Chow, 2001) gave momentum to the trend of construction of large glazed buildings during the Industrial Revolution in the late part of the century. The modern atrium design passed through ups and downs with its second revival being seen during the late 20th century with the most famous example being the Atlanta Regency Hotel, located in the state of Atlanta, USA. The atrium in the hotel design was used as a light well, creating a large open space with the guest’s balconies facing inwards. This design made use of natural lighting and ventilation and also was the first time a wall-climber elevator was used, creating a dynamic stimulating interior for the guests. For its commercial success, this vertical design was replicated afterwards in other hotels and shopping malls.

Although to this point most of the atrium examples reached into practical benefits of the atrium in integrating natural services into the built environment, their main design focus was centred in providing an awe-inspiring sensation to occupants. The latent potential of atria for environmental purposes only got attention later on, around the late 70s and early 80s (Ahmad, 2000), when the oil crisis came about, the atrium implications for energy savings in the built environment became relevant. This created two different applications of atria in buildings depending on the focus of the design, described creatively by Saxon in 1986 (Saxon, 1986) as

“carnivorous” and “herbivorous” approaches. The carnivorous design approach is based on creating this awe- spiring feeling, relying on high-end engineering technology to deliver megastructures with futuristic look and optimistic intentions. While the herbivorous approach is focused on what is today the broader definition of sustainability, a design that not only takes into account the environmental implications of certain design choices

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approach should not be mistaken as a simpler solution. Although it is more simplistic considering that it relies more on using different passive technologies to achieve synergistically energy savings in the built environment, it is also based on high-end engineering, technology and knowledge, but instead having as their main objective to deliver solutions that are truly sustainable in the long term.

The design influence in the overall efficiency of atria for energy savings in the built environment became and is currently a well explored research topic. Design investigations vary between understanding how the design, basically translated as dimensions (width, length and height) and glazing area sizes, influence the overall energy consumption of buildings in different climate properties (Aldawoud, 2013; Danielski, 2016; Heier and Österbring, 2012; Taleghani, 2014; Wall, 1996; Wang, 2017). While other design choices like shading techniques and different glazing materials are also explored in order to understand how different alternatives can contribute to mainly reducing heating and cooling demands (Czachura, 2019).

The classification of atria design varies according to its disposition to the main volume of the building. Figure 3 shows the most common atrium designs.

Figure 3. The 4 classifications of atria types, Source: Hung and Chow, 2001

The atrium general benefits for most types of building applications, according to Hung (Hung and Chow, 2001) are:

● Decrease in heating demands during colder periods of the year

● Increase in incident daylight into the indoor environment

● Reduction of electricity demands during daytime

● Creation of a more natural built environment

● Use of less and lighter materials for construction of additional spaces

● Lower construction time then regular building structures

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The most common problems related to the implementation of atria in the built environment are:

● Increase in cooling demands during the hotter periods of the year

● Increase in energy demands for maintaining the operation of the additional space (ventilation, operation processes, etc…)

● Solar glare indoors from excessive glazing area

● Tougher fire prevention measures and design restrictions for maintaining minimum safety requirements

● Conflict with the overall design of neighboring buildings

The balance between the benefits and disadvantages related to the final energy demands of atria will always depend on proper design. But one fact is common to all design configurations, too much unnecessary glazing area will only increase heating effects creating a “sauna”, increasing cooling demands and jeopardizing the comfort of inhabitants (Heier and Österbring, 2012; Wall, 1996).

The most appropriate atria designs vary between climates. Generally, square shaped atria (with higher aspect ratio between length and width, closer to 1) will fare better in terms of energy consumption when compared to elongated atria in all climates. The higher symmetry between the atria plans will provide a more homogeneous distribution of incident solar radiation (Aldawoud, 2013). In hotter dry and humid climates a high rise atrium with a centralized well, will fair better in terms of energy consumption for heating and cooling, while in temperate and colder climates low rise atrium with glazing area sizes around 20% to 30% of the total floor area will reduce energy demands, although with significant increases in cooling demands (Aldawoud, 2013).

According to Wang (Wang, 2017) the height and glazing area sizes of centralized atria influence can be explained by the temperature variation across the volume of the atrium and the amount of sunlight and solar radiation that reaches the floor area of the atrium. In high rise atria, solar radiation and light can't reach the lower parts of the well and floor, which will cause a vertical variation of temperatures in the atria volume. In this case, the atrium glazing area size optimization should be focused then in guaranteeing the best possible use of the natural daylight for the benefit of the indoor environment for decreasing electricity consumption and maintaining comfort and fire safety standards, while keeping heating and specially cooling demands as low as possible. For the low-rise atria this temperature variation does not occur. Since the radiation and light reaches the whole volume and floor of the atria, the glazing area size design will be limited mainly by the increase in cooling and heating demands. For this research is important to highlight some of Wang’s results that for glazing area sizes from 7% to 40% from atrium heights between 4.5 and 75 meters, that cooling demands rise significantly for the low-rise atrium when glazing areas size approach 30 to 40% of total floor area.

The California Energy Commission (California Energy Commission 2019 Building Energy Efficiency Standards, 2019) standard recommendations set only that a minimum limit of 3% of glazing area based on total covered floor area for ceiling heights below 15ft (or 4.57 meters) should be maintained, as long as 75% of the room is illuminated by natural daylight when no indoor light source is present. The North American skylight contractors VELUX (Velux Skylights, 2020) and Sterlingbuild (Sterlingbuild, 2020), or what can be considered in this case as expert recommendations, advise that the glazed area should vary between 5% and 20% of the total floor area at most.

When considering other types of atria design, those that allow solar radiation and light to reach a bigger portion of the indoor open space created by the atrium, like the semi-enclosed, attached or linear configurations, a different approach should be taken to properly compare the influence of the atrium design in the buildings

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the shape factor of the building with the atrium implementation can be used to understand the variations in thermal properties and explain the related variations in energy demands between buildings that can be considered similar in overall design. The shape factor is the ratio between the thermal envelope (area of the building that exchanges heat with the outdoor environment) and the total volume of the building. The ratio of the factor weights the variations in total area that actively loses or gains heat to the outside environment while increasing the total volume of the building that will need to be maintained under thermal and lighting comfort conditions with the additional volume of the atrium. It expresses the compactness of a certain building and can be used as a better approach for evaluation of the atrium influences in designs that the glazing height and area are not the main parameters to base the analysis. The implementation of atria that contributes to lower shape factors of a building, are found to have lower energy demands when compared to the same building without an atrium and higher shape factor. Therefore, the atrium should reduce total thermal envelope area while increasing the volume of the building to its maximum.

Although the atrium implications for the built environment are well known in the technical sphere, the scope of most studies are limited to improving the understanding on how certain design choices affect final energy demands, with little attention given to the environmental impact or social benefits of the atria implementation.

Currently society faces the threat of climate change and the continuous degradation of natural resources both caused by unchecked anthropogenic growth. Worldwide, different frameworks, agreements and groups have been created to discuss, develop and establish new measures and policies to reduce the impact of growth. One of such efforts was set by the UN 2030 Framework on Climate and Energy (United Nations Framework Convention on Climate Change Handbook, 2006). The commissions work as a framework for the signatory countries, establishing collective and individual targets in order to curb the already seen effects of climate change until 2030 and beyond. These targets focus mainly on establishing recommendations for decreasing greenhouse gases (GHG) emissions, increasing the shares of renewable energy production sources in the country's production mixes and increasing energy efficiency both in primary energy production and final energy consumption.

Improving energy efficiency on final energy consumption is greatly related to reducing heating and cooling demands on the built environment. This can be achieved either by developing new technologies in heating and cooling production in terms of more efficient means of active or passive production or by reducing losses during operation which mostly comes by implementing better systems of insulation or by innovative designs that can promote energy savings. Worldwide residential and service sectors of society are responsible for almost 30% of total energy consumption and from this total, close to 70% are due to space and water heating demands. (District heating needs flexibility to navigate the energy transition – Analysis, 2019). Global energy demand has increased 2.3% in 2018, the biggest increase in the last decade, while CO2 emissions per energy generation, or CO2 intensity, has remained steady, around 50 Gton/GWh for the same period, but a 1.7% or 33 Gtons of CO2 increase was observed in 2018 for total emissions of energy-related generation sector.

Despite an observed decrease in heating energy intensity worldwide of 3% per year since 2010, which can be interpreted as advances in heating efficiency and better building designs, most part of energy generation still comes from burning of fossil fuels like coal and the most recent predilection for natural gas. Although recently a steady increase in renewable energy generation like solar and offshore wind has been observed (31% and 20%

respectively in 2018), these still aren't enough to supply the global increase in energy demand (Global energy demand rose by 2.3% in 2018, its fastest pace in the last decade – News, 2019.). In overall, global CO2 emissions reduction from national and international commitments agreed through the UN Framework Convention on

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mitigative climate change goals, where currently, from the 1.7% increase in global emissions mentioned, 28% or 9.2 GTons of CO2 are attributed to the building sector (Perspectives for the Clean Energy Transition – Analysis, 2019).

Sweden is pointed as the world leader in low-carbon economy by the IEA, with the lowest share of fossil fuels in its electricity production and second lowest carbon intensity economy (Sweden is a leader in the energy transition, according to latest IEA country review – News, 2019). From a total of average 378 TWh of final energy use, 146 TWh or 39% are due to building and service sector with heating demands only, comprising 46 TWh or 32% of the total, second only to electricity demands representing 76 TWh or 50% of the total final consumption (Energimyndigheten, 2020). For Residential Multi-dwellings and commercial buildings, district heating is the most common heating carrier, represented 35% of the total heating demand (District heating needs flexibility to navigate the energy transition – Analysis, 2019), but in most houses, electricity dependent systems are still preferred such as heating pumps, supplying close one third of the market, and biofuels are second in preference with a 10% share, followed by petroleum products burners with close to 10% share of the final demand (Värmemarknad Sverige, 2020).

Total final energy use in the country has remained somewhat stable during the past decade. From 2010, where final energy consumption was 394 GWh to 2018 latest statistics from the Swedish Energy Agency show a value of 372 GWh, a 1.5% decrease when compared to the previous year and average between 2010 to 2018 of 378 GWh. CO2 intensity of final energy use has also been steadily decreasing. From 2010 to 2017 an average reduction of 2.35% was registered in the country, and in 2016 from 27.2 to 26.7 tCO2/GWh in 2017, a 1.84%

reduction.

Electricity and heat generation in Sweden can be considered to be mostly renewable when compared to other members of the IEA. In 2016, most of the country's electricity generation was divided between nuclear power, with a 40% share and hydropower representing 41% of the total. Wind power generation has experienced an increase of 377% in recent years, from 3487 GWh in 2010 to 16623 GWh in 2018, with what is now 10% of the generation market and the remaining 9% being the outputs from combined burning heat and power, industrial generation of heat and power and thermal technologies. In great part the cleaner heat generation from the country can be attributed to the transition from heating systems using direct electric and petroleum products burners to heat pumps that started in the 70s and saw great development during the 90s and stabilized with slight retraction from 2005 to 2015 (Johansson, 2017). Strong industrialization and government incentives to alternative technologies to oil fuelled burners in order to thwart the impact of the oil crisis in the 80s led to what is today the greatest market penetration and heat supply per capita from heat pumps in Europe.

While in the rest of the world 3% of the heat energy supply is credited to heat pumps, as mentioned 33% of the heat demand in Sweden comes from heat pumps, in small houses, more than half are using some kind of heat pump system (Johansson, 2017). The recommendations of the UN Framework Convention on Climate Change and Energy state that by 2030 heat pump usage must reach the 10% mark with 50% increase in efficiency in energy performance and decrease in purchase prices (Heat pumps – Tracking Buildings 2019 – Analysis, 2019).

Although this transition seems at first beneficial when considering reduction in emissions of greenhouse gases coming directly from heating systems, it is argued that the increase in electricity demand should be covered by renewable technologies to be truly considered an advance in tackling the climate change problem. If the increase is left to be covered by nuclear power generation or even worse marginal electricity generation sources like coal plants and other high CO2 emission generators, the benefits of such a transition can be contested.

By 2050, it is estimated that the implementation of passive techniques for energy saving in the building sector in Sweden, will be able to reduce the energy demands of the new buildings to a 10 to 15% share of the total for the

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residential and service sectors when compared to older building designs with no such passive technologies (Värmemarknad Sverige, 2020).

Therefore, to tackle climate change through transformation of the built environment, along with the implementation of best available technologies, must be the development of innovative designs for increasing efficiency in heat and electricity use. But forgetting to give attention as well to the overall impact the atria implementation brings, not only during its operation, but also during production of the used materials and construction, won’t paint the full picture regarding this solution’s sustainability.

Using the selected case study, this research intends to start this discussion, by determining not only if the implementation of the atria can be beneficial in terms of reducing heat loses of the building but also can be better when considering the overall environmental impact of the production of used materials. The comparison presented by the case study is between the business-as-usual approach of renovating old structures (in this case weather damaged walls) to improve thermal properties to meet current energy efficiency standards or the construction of atria that allows some of the older structures to be maintained. The selected case study was The Palmcrantzskolan building, located in the city of Östersund in Sweden, is undergoing renovations for it’s reopening as the Internationella Engelska Skolan (or International English School in english) scheduled for August 2020. These renovations include the refurbishment or complete replacement of the facade walls of 7 indoor gardens in a large section of the building.

This research entitled “Conditioned atria in the built environment - A possible solution for unsustainable urbanization and climate change in Nordic climates?” will answer the question: can the atria implementation be also beneficial in terms of lowering overall environmental impacts along with reducing heat loses when compared to the refurbishment of older buildings in Sweden?

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2.Methodology

2.1. Case Study - The Palmcrantzskolan Building

Figure 1 shows the plan section of the Palmcrantzskolan building and the walls under scrutiny for this study. The walls from gardens 1 and 2 didn’t undergo renovations, highlighted in Figure 1 by the yellow lines, while gardens 3 to 7 had some of the walls renovated represented by the red lines. Figure 2 and 3 were taken at the building site to show the current state of the indoor gardens, which so far have no planned use for the reopening of the school.

Figure 1. The Palmcrantzskolan Building Plan

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Figure 2. Garden 1 Photo

Figure 3. Garden 4 Photo

2.2. Atria Design

The glazing area size will be the most important parameter to be analysed for maintaining lower cooling and heating demands in the atria, since the design will be of a low-rise centred atria, where heat and the sunlight of

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Table 1 shows the dimensions of the gardens and atria heights. The used heights were considered to be the same level from the highest facade walls of the garden while no angle was considered for the roof of the atria.

Table 1. Gardens Dimensions

Garden Length [m] Width [m] Garden Area

[m²] Atrium Height [m] Volume [m³]

IGN 1 22.69 8.74 198.33 4.15 823.08

IGN 2 28.05 8.76 191.04 4.09 780.60

IGN 3 30.86 7.58 233.92 4.35 1017.55

IGN 4 30.86 11.85 365.69 4.35 1590.76

IGN 5 24.24 9.26 224.44 4.35 976.31

IGN 6 24.24 12.43 301.33 4.35 1310.77

IGN 7 14.71 7.69 113.11 4.35 492.01

Total - - 1682.50 - 6991.08

The gardens 1, 3, 4, 5, 6 and 7 walls were oriented according to Figure 4. Drawings of the new walls and windows were provided by Skanska (Welcome to Skanska, 2020) the company ahead of the renovations of the building.

The drawings of section plans used to model the walls are displayed in Annex 2. Windows and doors dimensions and glazing materials are displayed in Annex 3, as well as their locations on the garden walls. The total glazing areas were considered to be shared between the opaque surfaces of the frames (23%) and glass surfaces (77%).

Figure 4. Gardens Walls Orientation

Besides garden 2 (IGN 2) all other gardens follow the geometry exemplified in Figure 4. The exceptional geometry of garden 2 is represented on the following Figure 5.

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Figure 5. Garden 2 Walls Orientation

The total glazing areas for the atria were selected using recommendations from The North American skylight contractors VELUX and Sterlingbuild and also the conclusions from Wang (Wang, 2017) regarding the low-rise centred atria design, all mentioned in the Introduction (Section 1). Therefore, the range between 5% and 20%

of the total floor area for the total glazing area of the atria was chosen as proper for this study as a first step of investigation, with later analysis of the energy break-even point for each of the gardens.

The total glazing, aluminium frames, insulated roof areas for each of the gardens are displayed in Table 2. The same values for the optimized glazing areas sizes are displayed in Table 3.

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Table 2. Glazing, aluminium frames, insulated roof areas between 5% to 20% of total glazing area A5 (5% Glazed Area Scenario)

Garden

Insulated Roof Area

[m²] Glazed Area [m²]

Aluminium Frame Area [m²]

Glazed + Frames Areas [m²]

IGN 1 185.45 9.92 2.96 12.88

IGN 2 178.64 9.55 2.85 12.41

IGN 3 218.73 11.70 3.49 15.19

IGN 4 341.94 18.28 5.46 23.75

IGN 5 209.86 11.22 3.35 14.57

IGN 6 281.76 15.07 4.50 19.57

IGN 7 105.76 5.66 1.69 7.34

A10 (10% Glazed Area Scenario)

Garden

Insulated Roof Area

IGN 1 172.58 19.83 5.92 25.76

IGN 2 166.23 19.10 5.71 24.81

IGN 3 203.54 23.39 6.99 30.38

IGN 4 318.20 36.57 10.92 47.49

IGN 5 195.29 22.44 6.70 29.15

IGN 6 262.19 30.13 9.00 39.13

IGN 7 98.42 11.31 3.38 14.69

A15 (15% Glazed Area Scenario) Garden

Insulated Roof Area

IGN 1 159.70 29.75 8.89 38.64

IGN 2 153.83 28.66 8.56 37.22

IGN 3 188.35 35.09 10.48 45.57

IGN 4 294.45 54.85 16.38 71.24

IGN 5 180.72 33.67 10.06 43.72

IGN 6 242.63 45.20 13.50 58.70

IGN 7 91.07 16.97 5.07 22.03

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Table 2. Glazing, aluminium frames, insulated roof areas between 5% to 20% of total glazing area (continuation)

A20 (20% Glazed Area Scenario)

Garden

Insulated Roof Area

IGN 1 146.82 39.67 11.85 51.52

IGN 2 141.42 38.21 11.41 49.62

IGN 3 173.16 46.78 13.97 60.76

IGN 4 270.71 73.14 21.85 94.98

IGN 5 166.14 44.89 13.41 58.30

IGN 6 223.06 60.27 18.00 78.27

IGN 7 83.73 22.62 6.76 29.38

The analysis is separated in two parts: the first one is based on the VIP-Energy software models to determine the differences between the heat loses in the restoration of the school building walls facing the indoor gardens and the atria glazed roofs and the heating demands of the different atria glazing areas sizes. The second part of the analysis aims to determine the differences in environmental impacts (based on 3 indicators explained in the following Section 2.4.1) of the materials used in the restoration of the walls and the construction of the atria for the glazing area sizes using the SimaPro software.

2.3.Input Parameters for the VIP-Energy Models 2.3.1.Envelope Scenarios

The thermal envelope scenarios “OLD” and “NEW” represent respectively, the old walls configurations before any renovations were done and after the renovations were done. These two scenarios were included to serve as a base for evaluating how the renovations will influence the energy balance of the gardens facades when compared with the possible construction of the conditioned atria. The NEW envelope scenario will be modelled in SimaPRO along with the atria envelope scenarios for comparison between the total impact of utilized materials.

The atria envelope scenarios named “A5”, “A10”, “A15”, “A20” and “BE” represent the implementation of the atria in the indoor gardens with increasing glazed areas. The A5 scenario represents the 5% glazing area size from the total floor area in the atria, the same can be extended for the other scenarios with 10%, 15% and 20%

glazing area sizes respectively. The BE envelope scenario is the break-even point for the glazing area size in each of the seven gardens. The break-even point was calculated using the OLD and NEW scenarios as reference, consisting of the minimum glazing area size necessary to have a final energy demand equal to the base scenarios (OLD and NEW) heat loses (equal to the heat transmission minus incident solar radiation through the window).

The OLD and NEW envelope scenarios consider only the energy transfer occurring between the indoor and

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considered adiabatic in all the scenarios. This modelling choice permits isolating the influences of the changes done in the walls, windows and by the implementation of the atria for the thermal transfer of the building.

In resume the 7 thermal envelope scenarios explored are:

● OLD scenario - Old walls configurations before renovations

● NEW scenario - New walls configurations after renovations

● A5 - Atrium with 5% glazing area size

● BE – Break-even point for the glazing area size

The heat loses/energy demand analysis comprises a total of 7 thermal envelope scenarios (OLD, NEW and the atria glazing areas sizes, including the break-even point) for each of the 7 indoor gardens that differ regarding the walls configuration and the atria glazed area sizes. Therefore, a total of 49 models were used for this first analysis using VIP-Energy software. VIP-Energy is a dynamic energy balance analysis tool that can simulate energy transfers in buildings (“StruSoft | VIP-Energy,” 2020).

2.3.2.Climate Conditions

Weather variations were taken from the VIP-Energy database for the city of Östersund represented as the average annual weather variation from the period of 1981 to 2010. The database includes average hourly values for solar radiation, outdoor temperature, wind velocity and relative humidity. The average values for each of the climate parameters for the whole one year are represented at following Table 3. The horizontal solar angle was considered to be 20° in all directions and ground reflection is set to 20%, outdoor pressure is 1 atm, while wind velocity is considered to be 70% of the climate file in all directions. The graphical representation of each climate file's averages for the period of one year were included in Annex 1.

Table 3. Climate Parameters Average Values

Values Solar Radiation [W/m2] Wind Velocity [m/s] Outside

Temperature [°C] Relative Humidity [%]

Min. 0 0 -27 25

Average 96 3 3 78

Max. 813 11 29 100

2.3.3.Walls, Windows and Atria Materials and Thermal Properties

The materials from the walls were selected from the VIP-Energy database according to the drawings of section plans displayed in Annex 2. The NEW and atria (insulated roof) scenarios followed the drawing provided by Skanska (Welcome to Skanska, 2020). The OLD envelope scenario walls system configuration was modelled according to in site observation of some of the remaining walls and using old drawings retrieved from the

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Östersund Municipality online archive (Ritningar och handlingar, 2020) under the building, living and environment section. Table 4 shows the materials selected from the VIP-Energy database.

According to the old plans of the building and what was observed in site the old walls of the building were composed of 2 different system. For the VIP-Energy models the first one was composed of a weatherboard (9 mm in width) above an insulated panel (stone wool insulation 195 mm in width with vertical 195x45 mm s600 wood rules) and the other 2 clay brick layers (120 mm in width) with an inner stone wool insulation layer (also 120 mm in width) with an inner room plaster layer (0.001 mm in width). The walls and roofs systems for the OLD, NEW and atria envelope scenarios can be found in Annex 4.

The walls corners were not modelled, and therefore, considered to be an extension of the longer walls of the gardens (Walls 1 and 3, and for garden 2 also Wall 5 were extended).

Table 4. Materials and Wall Parts Thermal Properties

Material/Wall Parts

Heat Conductance

[W/m.K]

Density [kg/m³]

Heat Capacity [J/m.K]

Exp. Plastics 38 (plastic

film) 0.038 25.0 1400.0

Eternit (weather board) 0.240 1950.0 840.0

Gypsum Board 0.220 900.0 1100.0

KC-Plaster 1.000 1800.0 800.0

Leca Blocks 0.210 650.0 800.0

Mineral wool 36 0.036 50.0 840.0

Mineral wool 40 0.040 80.0 840.0

Facade Brick 0.600 1500.0 840.0

Wood Pine 0.140 500.0 2300.0

First insulation layer +

Horizontal Bars s600 0.040 80.0 840.0

Second insulation layer +

Vertical Bars s600 0.042 111.5 949.5

Third insulation layer +

Horizontal Bars s600 0.043 117.9 971.6

Third insulation layer + Horizontal Bars s600 (wall

type V4) 0.041 88.2 868.4

Old walls insulation +

Vertical Bars s600 0.042 111.5 949.5

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Table 5 contains the thermal envelopes and U-values of the sums of all the walls and windows in the OLD and NEW scenarios and for the atria scenarios (from 5% to 20% glazing area sizes) the sum of the insulated roof and glazing. The same parameters for each of the windows, walls, insulated roofs and atria glazing individually can be found in Annexes 3 and 4 respectively.

Table 5. Average Thermal Envelopes and U-values of all envelope scenarios for the walls systems (walls and windows together)

Gardens

OLD NEW Atria

Thermal Envelope Area [m²]

U-value [W/m²K]

U-value A5 [W/m²K]

U-value A10 [W/m²K]

IGN 1 267.81 0.491 267.81 0.322 198.33

0.199 0.248 0.297 0.345 IGN 2 328.28 0.498 328.28 0.325 191.05

IGN 3 324.69 0.832 324.69 0.428 233.92 IGN 4 355.22 0.848 355.22 0.435 365.69 IGN 5 278.21 0.674 278.21 0.421 224.43 IGN 6 305.82 0.736 305.82 0.401 301.33 IGN 7 184.17 0.801 184.17 0.432 113.10

Total 2044.21 - 2044.20 1627.85 - - - -

Windows glazing materials were separated in 3 distinct types: Coated glass with 3 panes, Coated glass with 2 panes and normal clear glass with 2 panes. The NEW and atria scenarios were modelled with the 3 panes windows according to renovations schematics and for it’s increased thermal benefits. The OLD scenario was modelled using 2 panes windows. The Table 6 shows the glass share, windows solar transmittance and thermal properties used in the models.

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Table 6. Windows Properties

Windows Glass

Share [%]

Total Solar Transmittance

(g-value) [%]

Direct Solar Transmittance

(g-value) [%]

U-value [W/m²K]

Infiltration Factor q50

[L/s.m²]

Coated 3 Panes 77 39 36 0.9 0.5

Coated 2 Panes 77 70 60 2.0 0.8

Clear Glass 2 Panes 77 86 83 2.0 0.8

2.3.4.Operation Time Schedule of The School

Operational of the school building was considered to vary between 2 different operational cases named: “Day”, and “Night”. As the names imply, Day is the operation during school hours of the week, from Monday to Friday, from 8 a.m. to 16 a.m. The Night operational case is used during the remaining time, when no activity is present in the school building, including the summer vacation period of the school, from weeks 25 to 33.

The operation schedule for the OLD and NEW scenarios considered only the indoor maximum and minimum temperatures for comfort (25°C and 22°C respectively), since no floor area and volume of the building was added to the model. The implications of this simplification for the VIP-Energy models are discussed in Section 5.1 (technical aspects discussion).

The operation distribution during the year is represented in Table 7.

Table 7. Weekly, Daily and Yearly Operation Schedule

Operation Case Name Week Day Day time

[Hours] Weeks of the Year

Night Monday to

Sunday

Remaining

Time 2 - 51

Day Monday to Friday 8-16 2 - 24 / 34 – 51

The values for the parameters used to represent the activity in the school for each operational case are displayed in Table 8. The presented values are the standard values of VIP-Energy database for school building, with the exception of the Activity Energy to room air parameter which was based on the California Energy Commission 2019 Building Energy Efficiency Standards. The specified standard stipulates that a minimum of 0.65 Watts per square foot must be maintained as indoor lighting density. Converting to kWh per week (168h a week) this value can be translated to 6.99 W/m².

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Table 8. Parameters Values for Daily Activity in the School

Operation Case Name

Activity

Energy Operation Energy Person Energy [W/m²]

Moisture to Room

air [mg/s.m²]

Room Temperature to Room

air [W/m²]

To Room air [W/m²]

External [W/m²]

Highest [°C]

Lowest [°C]

Night 0.00 0 0.0 0 0.0 25 22

Day 6.99 1 0.4 12 0.8 25 22

Day LOW 0.00 1 0.4 12 0.8 25 22

2.3.5.HVAC System and Ventilation Values

Operation for ventilation was considered only for the atria scenarios, since as mentioned before, no floor area or volume of indoor spaces were specified for the OLD and NEW scenarios. Heat recovery efficiency of the HVAC system was set at a constant 85% value with a temperature range for measurements between -50°C and 50°C.

The following Table 9 shows the parameters values used for the ventilation system which follows the same operational schedule during the year shown in the previous Section 2.3.4.

Table 9. Ventilation Parameters Values

Schedule Supply air fan Pressure [Pa]

Fan Efficiency

[%]

Extract air fan pressure [Pa]

Fan Efficiency

[%]

Day Flow [L/s.m²]

Night Flow [L/s.m²]

(Remaining Time)

School 300 20 400 20 0.762 0.1

2.3.6.Energy Comparison Parameters

The parameters used to compare the energy transmissions/demands were heat transmission (through the walls windows and doors), incident solar radiation through the windows, and cooling (passive cooling) and heating (active heating) demands, process energy indoors and power supply.

The parameters used for the evaluation of the results vary between the comparison of the OLD and NEW scenarios and atria scenarios. This is due to the fact that volume and floor area on the OLD and NEW scenarios from the school building were not considered. By the time of this research was being done the school was still undergoing reforms which made it complicated to determine which rooms and for what the internal rooms would be used for. Therefore, the parameters dependent on the volume of the adjacent classrooms like cooling and heating demand, process energy indoors, power supply, ventilation energy demand, ventilation heat recovery, person heat and latent heat could not be considered on the energy comparison of the OLD and NEW scenarios.

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The first energy comparison made on this method is aimed to determine the difference between the wall and atrium design in terms of heat loss/gain. The energy parameters were used according to the following Formula 1:

𝐸₁ = 𝐸ℎ𝑒𝑎𝑡 𝑡𝑟𝑎𝑛𝑠𝑚𝑖𝑠𝑠𝑖𝑜𝑛 - 𝐸𝑠𝑜𝑙𝑎𝑟 𝑟𝑎𝑑𝑖𝑎𝑡𝑖𝑜𝑛 Eq.1

For the atria scenarios the energy parameters used were the cooling and heating demands, process energy indoors (electricity for lighting which depend only on direct activity of the atria spaces) and power supply (ventilation fans and other appliances based on climate regulation that do not depend on direct activity of the spaces). These were selected because they represent the final energy demand (or additional energy to the overall consumption of the school building) that is necessary to make these new spaces habitable. The following Formula 2 shows the composition of the second energy comparison using these energy parameters:

𝐸2= 𝐸𝑐𝑜𝑜𝑙𝑖𝑛𝑔 𝑑𝑒𝑚𝑎𝑛𝑑 + 𝐸ℎ𝑒𝑎𝑡𝑖𝑛𝑔 𝑑𝑒𝑚𝑎𝑛𝑑+ 𝐸𝑝𝑟𝑜𝑐𝑒𝑠𝑠 𝑒𝑛𝑒𝑟𝑔𝑦 𝑖𝑛𝑑𝑜𝑜𝑟𝑠+ 𝐸𝑝𝑜𝑤𝑒𝑟 𝑠𝑢𝑝𝑝𝑙𝑦 Eq.2

2.3.7.Break-even point for the Glazing Area Sizes

The break-even point (BE) for the atria glazed area sizes for each of the gardens was done based on the comparison between the E1 of the OLD and NEW scenarios and the final energy demand of the atria scenarios.

Considering that the cooling and heating demands increases are consequential with the implementation of atria in the gardens the objective of finding the break-even point is to find the maximum value of glazing area that the implementation of the atria yearly final energy demand becomes equivalent to the overall heat transmission of the OLD and NEW scenarios. This means that for any other value of glazing area size above the break-even point, the energy demand of the atria will higher than the benefits of the decreased in heat loss of the atria implementation which would be counterproductive. The use of alternative materials wasn’t considered on the scope of this study analysis, concentrating only on variations of glazing area sizes of the atria.

The weekly and heat transmission, solar radiation, cooling, and heating demands were observed to increase linearly with the increase of glazing area in the atria. Using this fact, the weekly values for each of these parameters were interpolated for other values of glazing areas sizes, without the need for generating and running additional models in VIP-Energy. The interpolation was done using the weekly values of the parameters for the 5%, 10%, 15% and 20% glazing areas with 0.1% regular steps.

The sensitivity of this interpolation was tested along with the results generated by VIP-Energy for the same values of glazing area sizes for each of the gardens. The biggest discrepancies were between the cooling demands values, with a maximum of +4% variation above the results from the software. This translates, for example, in the gardens 1 and 2 of a variation in the percentage of glazing area of -1.4%.

The heat transmission, solar radiation and heating demands returned discrepancies below 1% with no significant variation for the final energy demands values.

The gardens glazing area break-even curves are displayed in Annex 5.

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2.4.Impact Assessment Models in SimaPro 2.4.1.Modelled Scenarios

The SimaPro models were used for comparison between the impacts regarding the renovation of the building walls and the construction of the atria. Therefore, only the materials used to build the new walls were considered as for the materials necessary for the insulated roof and the glazed roof in the atria scenarios and for the break- even points were applicable. SimaPro is a life-cycle analysis tool that uses an extensive database of different processes energy and emissions loads to generate environmental impact results across multiple indicators (“SimaPro | The world’s leading LCA software,” 2020).

The selected database library for this analysis was the Ecoinvent 3 (allocation, cut-off by classification, unit).

The selected methods for comparison between the environmental impacts of the renovation of the walls and construction of the atria were Cumulative Energy Demand, Global Warming Potential over 100 years spam (GWP 100a) and Ecosystem Damage Potential. These methods were selected to better evaluate the different impacts that each of the used materials can generate regarding the environment; being GWP a100 selected to reflect their contributions to climate change, Ecosystem Damage to represent which of the materials could affect Sweden’s local ecosystems the most and Cumulative Energy Demand to better base the comparison between heat loses/gains and the final energy demands between the proposed envelope scenarios.

The materials representations references from the SimaPro database library are displayed in the following Table 10.

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Table 10. Materials reference in SimaPro Database Library

Material SimaPro Library

Stone Wool 40 and 36 Stone wool {GLO} | market for stone wool | Cut-off, U

Cedral Plank

Fibre cement facing tile, small format {GLO} | market for | Cut- off, U

LC-Plaster Cover plaster mineral {GLO} | market for | Cut-off, U

Gypsum Board Gypsum plasterboard {GLO} | market for | Cut-off, U Facade Bricks Clay brick {GLO} | market for | Cut-off, U

LECA Block

Lightweight concrete block, expanded clay {RoW} | market for Lightweight concrete block, expanded clay | Cut-off, U

Plastic Film

Packaging film, low density polyethylene {GLO} | market for | Cut-off, U

Triple Normal Glass Flat glass, uncoated {RER} | market for | Cut-off, U Plywood Plywood, for outdoor use {RER} | market for | Cut-off, U

External Vertical Wood Rules, Vertical Wood Rules, Horizontal Wood Rules, Horizontal Wood Rules Window Frame

Sawnwood, softwood, dried (u=10%), planed {RER} | market for | Cut-off, U

Weatherboard Particle board, cement bonded {GLO} | market for | Cut-off, U

Aluminium Frames

Window frame, aluminium, U=1.6 W/m2K {GLO} | market for | Cut-off, U

Triple Coated Glass Glazing, triple, U<0.5 W/m2K {GLO} | market for | Cut-off, U

Wood Joists (45x195mm, s450) Joist, engineered wood {GLO} | market for | Cut-off, U

Density System Mataki Unotech

Bitumen Seal, polymer EP4 flame retardant {GLO} | market for

| Cut-off, U

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2.4.2.Materials Amounts

The materials amounts were determined by volume using thickness, length and heights of the wall’s section drawings from Annex 2. As mentioned, the walls corners were not modelled in SimaPro as well, and therefore, were considered to be an extension of the longer walls of the gardens (Walls 1 and 3, and Wall 5 in garden 2).

The walls materials volumes, areas and weights as for the adopted densities and thickness are displayed in Table 11 and 12 for the NEW and atria envelope scenarios, respectively. The inputs for the selected materials in SimaPro can vary between volume, weight, length and area.

Table 11. NEW envelope scenario materials amounts SimaPro Materials Quantitites NEW Envelope Scenario Material (Density in

kg/m3) Garden 1 Garden 2 Garden 3 Garden 4 Garden 5 Garden 6 Garden 7

Stone wool (40) [kg] 1816 2642 1808 1829 1503 1476 754

Gypsum plasterboard

(640) [kg] 2630 4163 2559 2530 1745 2196 1102

Packaging film (0.857)

[kg] 33 48 33 33 22 28 14

Fibre cement facing

tile (1300) [kg] 1032 2675 900 818 531 924 431

Flat glass, uncoated

(3 x 6 mm 2531) [kg] 34 369.89 709 577 468 184 394

Clay Brick (1900) [kg] 0 0 0 0 17464 0 0

Lightweight Concrete

Block (350) [kg] 0 0 0 0 1454 0 0

Cover Plaster (860)

[kg] 0 0 0 0 18 0 0

Window frame,

aluminium [m2] 11.00 12.37 25.90 29.52 15.87 14.19 11.56

Glazing Triple [m2] 34.58 17.04 40.04 60.82 28.99 35.38 12.76

Plywood [m3] 2.39 1.53 2.18 2.30 2.10 2.00 0.93

Sawnwood [m3] 5.05 7.15 6.22 5.77 4.72 3.78 2.74

Particle board [m3] 2.26 2.97 1.81 1.85 1.46 1.48 0.88

The materials volumes, areas and weights of the insulated roof and glazing of the atria envelope scenarios as for the adopted densities and thickness are displayed in the following Table 12.

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Table 12. Atria envelope scenarios materials amounts SimaPro Materials Quantities

A5 Envelope Scenario

Material (Density in kg/m3) Garden 3 Garden 4 Garden 5 Garden 6 Garden 7

Stone wool (40) [kg] 2187 3419 2099 2818 1058

Gypsum plasterboard (640) [kg] 2156 3370 2068 2777 1042

Bitumen seal (700 g/m²) [kg] 1203 1880 1154 1550 582

Window frame, aluminium [m2] 3.49 5.46 3.35 4.50 1.69

Glazing triple [m2] 11.70 18.28 11.22 15.07 5.66

Joist, engineered wood [m] 493.83 772.01 473.81 636.14 238.78 A10 Envelope Scenario

Stone wool (40) [kg] 2035 3182 1953 2622 984

Glazing triple [m2] 23.39 36.57 22.40 30.13 11.31

Stone wool (40) [kg] 1884 2945 1807 2426 911

Glazing triple [m2] 35.09 54.85 33.67 45.20 16.97

Stone wool (40) [kg] 1732 2707 1661 2231 837

Glazing triple [m2] 46.78 73.14 44.89 60.27 22.62

Joist, engineered wood [m] 415.86 650.12 399.00 535.69 201.08

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2.5.Methodology Limitations

The first limitation of the described method resides on the energy comparisons. By not considering the immediate adjacent floor areas and volumes to the gardens, some of the parameters necessary to better equilibrate the comparison between all the scenarios are missing. This leaves the final values of the OLD and NEW scenarios with a larger discrepancy when compared to the atria scenarios, that consider only the heat loses based on heat transmission and solar radiation through the windows, not being fully translated as heating or cooling demands of the building spaces like the atria in the gardens. This limitation will be later addressed in the discussion (Section 5.1) after the heat transmission, solar radiation and appliances demands values are calculated and can be compared between each other. Another limitation of this simplification is that the final energy demand of the atria cannot be weighed against the total energy demand of the school building which would be a useful way of interpreting the results.

Another weakness of the method is the fact that it doesn’t consider electricity savings due the implementation of the atria. The models where made based on weekly/monthly/yearly values instead of the hourly values in VIP-Energy. Considering that in Sweden the amount of daylight varies drastically over the year, to extend electricity saving in a weekly value could overestimate the electricity savings promoted by the atria and return values for the glazing that do not reflect the reality. To include the electricity savings the model would have to be based in hour steps which would increase calculations times and add to work time that the scope of this thesis could not accommodate. Although the method can maintain its current structure to accommodate this additional consideration based on the standards mentioned in the Introduction (Section 1).

The limitations on the SimaPro models are related to the range of the model which does not take into consideration the impacts (in all the 3 criteria) of the materials transportation during the assembly phase as for the energy and time necessary to complete the wall renovations or atria constructions. Regarding transportation of materials, it is safe to assume that, considering the atria requires a smaller quantity of materials, that are lighter and also less varied when compared to the NEW envelope scenario, would lead to smaller impacts regarding their transportation, further increasing the benefits of the atria, but that would have to be proven with further calculations.

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3.Results

3.1.Atria thermal properties and design for the Break-even point

The gardens 3 to 7 the linear regressions for the break-even points returned glazing area values below the 5%

from the total floor area, which would be less than the expert’s recommendation and considered to be insufficient to provide enough sunlight to shine to the indoor environment of the atria spaces. Therefore, the atria alternative cannot be considered worth it at this first analysis of the method for gardens 3, 4, 5 ,6 and 7 based on the energy demands and were left out of the comparisons using the break-even method.

Table 13. Thermal Envelopes and U-values of Gardens for the BE Scenario

Gardens

BE scenario Thermal

Envelope Area [m²]

U-value [W/m²K]

IGN 1 198.33 0.246

IGN 2 191.05 0.390

Using the break-even points, the glazing area shares of the total garden floor areas can be calculated. Table 14 shows the respective areas for the insulated roof, glazing and aluminium frames of the atria which were used for the calculations of the cooling, heating and amenities demands in VIP-Energy, as well for the impact indicators in SimaPro in the following results in Section 3.3.

Table 14. Areas for the insulated roof, glazing and aluminium frames for the break-even envelope scenario

BE scenario

Garden

Break-even points for the

glazing area share [%]

Insulated Roof Area [m²]

Glazed Area [m²]

IGN 1 9.8 173.09 19.44 5.81 25.24

IGN 2 24.6 130.01 41.40 12.37 53.77

3.2.Heat transmission, solar radiation, cooling and heating

demands, process energy indoors and power supply

results

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Table 15. Total yearly heat transmission Heat Transmission [kWh/year]

Garden OLD NEW A5 A10 A15 A20 BE

IGN 1 19415 - 5367 6960 8519 10074 6888

IGN 2 24067 - 5173 6705 8207 9705 11100

IGN 3 40158 20928 6321 8202 10042 11876 -

IGN 4 44828 23260 9885 12822 15698 18566 -

IGN 5 27612 17443 6064 7870 9635 11395 -

IGN 6 33435 18441 8145 10566 12936 15298 -

IGN 7 21938 11987 3076 3966 4855 5743 -

Considering the thermal envelopes and U-values presented in the previous Table 5 (Section 2.3.3) and Tables 13 and 14 (Section 3.1), the highest transmission values are found in all gardens for the OLD scenario, due to less layers of insulation combined with larger thermal envelope areas with the highest being from garden 4 and 6.

Following the same logic, lowest values of transmission are encountered in the A5 envelope scenarios, with yearly heat transmissions reductions from 65 % (garden 5) to 78% (garden 2). While for A20 envelope scenarios observed reductions were from 17% to 60% for the same gardens. In the BE scenario, heat transmission reductions were of 65% for garden 1 and 54% for garden 2. It is important to point out that for all gardens and envelope scenarios, the atria had lower heat transmission when compared to the NEW envelope scenarios.

The discrepancies between the gardens followed geometry or thermal envelope variations and the extension in which the renovations took place. While gardens 1 and 2 had the highest reductions of them all since no renovations were made. While for gardens 3 and 5 the highest reductions in transmission were observed respectively, since on them were also observed the greater reductions in thermal envelope with the atria implementation when compared to the NEW envelope scenario. In garden 4, the thermal envelope actually increased with the atria compared to the walls, but since U-values decreased significantly, from 0.848 and 0.435 W/m²K for the OLD and NEW scenarios and from 0.199, 0.248, 0.297, 0.345 W/m²K for A5 to A20 respectively, as observed in Table 5, reductions in transmission were closer to what of those observed in the gardens 3 and 5. Gardens 6 had the lowest of reductions, since thermal envelope variation was smaller and only 3 out of 4 walls were renovated. The garden with highest reductions where renovations were made was garden 7, which being the one with the smaller envelope area and discrepancies between the length and width ratio, the reduction of both thermal envelope and U-values had greater impact in reducing overall heat transmission.

The values for incident solar radiation through windows can be seen in the following Table 16.

Conditioned atria in the built environment - A possible solution for unsustainable urbanization and climate change in Nordic climates?

Master’s thesis

Two years

Environmental science

Conditioned atria in the built environment - A possible solution for unsustainable urbanization and climate change in Nordic climates?

Lucas Cupello de Vasconcellos

Acknowledgments

Abstract

Key Words

Table of Contents

1. Introduction

2.Methodology

2.1. Case Study - The Palmcrantzskolan Building

2.2. Atria Design

2.3.Input Parameters for the VIP-Energy Models 2.3.1.Envelope Scenarios

2.3.2.Climate Conditions

2.3.3.Walls, Windows and Atria Materials and Thermal Properties

2.3.4.Operation Time Schedule of The School

2.3.5.HVAC System and Ventilation Values

2.3.6.Energy Comparison Parameters

2.3.7.Break-even point for the Glazing Area Sizes

2.4.Impact Assessment Models in SimaPro 2.4.1.Modelled Scenarios

2.4.2.Materials Amounts

2.5.Methodology Limitations

3.Results

3.1.Atria thermal properties and design for the Break-even point

3.2.Heat transmission, solar radiation, cooling and heating

demands, process energy indoors and power supply

results