Building Simulation

Building simulation Comparative study

Athens, Architecture studio Jacob Brown s1650678

Climatic conditions ASHRE climate zone 3B (warm and dry climatic conditions) Sun angle diagram: Summer

The sun diagrams demonstrate that the sun-paths will de a issue to address in the design and strategy of the building with a high sun angle in the summer, along with a high level of solar radiation affecting the internal environments of the building as well. Shading options and positions of glazing will be important for maintaining a comfortable internal environment.

The prevailing wind direction is coming from the North to South, with the strongest winds in the winter months but even then the winds are not too strong, the wind direction will be something to factor into the strategy and design of the building when considering natural ventilation systems and internal air changes to ensure comfortable working environments.

Wind strength throughout the year

Sun angle diagram: Winter

Wind Rose

Other parts of the climate to consider are the temperatures and daylight levels, which again will also affect the internal environmental comfort both from temperature and possible glare.

The average temperature is 21 degrees with highs of 34 in the summer and lows of 5 degrees in the winter, so the main challenges for this environment will be providing adequate cooling. This is also important when considering the light levels with 75% of the days being sunny or partly-cloudy meaning the glazing will need to be carefully controlled possibly with shading options to avoid the full glare of the summer sun. However this also presents the opportunity for PV panels and renewable power generation.

Average temperatures and precipitation levels throughout the year

Overcast and sunny days annually

Metoblue; Data and graphs sourced from and available at: https://www.meteoblue.com/en/weather/ week/athens_greece_264371

Strategy The main strategy for the building is to provide shelter from the summer sun in the key rooms (cafe, seminar rooms and studio spaces) as well as social spaces, preventing excessive solar gain in working rooms, whilst providing suitable internal daylighting levels and comfortable temperature ranges for detailed working and activities.

Adequate glazing and access to external spaces for ventilation, comfort and daylighting (keeping the working environments between 200 and 650+ lux) are also important parts of the strategy to provide spaces that don’t feel uncomfortable with a lack of space or natural daylighting.

The use of photovoltaic (PV) panels on the south facing parts of the roof to generate electrical energy and reduce emissions will be used to take advantage of the high level of solar radiation in this climate.

The form of the building will be used create shading and to take advantage the wind direction for Natural ventilation system providing passive cross ventilation in the centre part of the building. The building form will also be designed to provide shading properties from the shape of the roof and overhangs on the sides, preventing excessive daylighting and solar gains.

The fixed elements of the strategy are the; occupant density set to slightly above the average level for a school building allowing more room for studio based working.

The building orientation will also be fixed with the shape and direction of the building important in the strategy for shading, light and ventilation purposes.

The U-value and building materials will also be fixed elements, suited for the climate.

Finally, the use of the internal spaces will also be fixed with the design of the glazing orientated to providing better lighting for specific places such as the studios, which will require higher LUX levels than the seminar rooms for example, therefore the rooms and there purposes will be fixed.

Materiality: Brick: U-value 0.44 (lower than the 0.75 average for Athens buildings) Walls (ASHRE, 2019) Roof Wood deck: U-value 0.22 (lower than the 0.55 average for Athens buildings) (Based on CIBSE TM46) The baseline materials and u-values were based on the ASHRE climatic standards for climatic zone 3B (warm and dry) alongside the CIBSE TM46 and CIBSE A guidelines for school and university buildings.

A-A

The design for option 1 is aimed at providing shading from the direct sunlight and high sun angles in the summer with the use of an overhanging roof element and the shape of the roof ‘pyramids’. The design aims to shade the skylights and create an area for the hot air to move out of the building through buoyancy, whilst maintaining some south-facing area for the PV panels.

Studio

PRODUCED BY AN AUTODESK STUDENT VERSION Circulation space

B-B

Utility and storage rooms Seminar rooms

The facade glazing is based on the exposure to the sun with smaller windows higher up the facade on the South, East and West façades.

The North facade has larger floor to ceiling windows to provide high daylight levels for the studio spaces.

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A-A

B-B

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Reception/ entrance

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The courtyard in the centre of the building acts as a cross-ventilation path using the North-south wind direction to help ventilate the spaces in the building. This space also acts as a social area and extension of the cafe space. It has glass walls allowing light to get into the core of the building as well with louvres above to prevent excessive light and radiation.

Cafe

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Option 1 Design

Plan

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Option 2 has similarities with option 1 with the overall design of the building including the shading, facade glazing and the courtyard.

However, the roof design is different with much less glazing than option 1 and the glazing is more focused to the spaces that require the light such as the studios.

This roof also has a larger South facing area then option 1, providing more room for PV panels and potentially a higher power generation.

NOISREV TNEDUTS KSEDOTUA NA YB DECUDORP

N NOISREV TNEDUTS KSEDOTUA NA YB DECUDORP

Option 2 Design

NOISREV TNEDUTS KSEDOTUA NA YB DECUDORP

Plan

Studio Circulation space

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B-B

Utility and storage rooms Seminar rooms Cafe Reception/ entrance

Similarly to option 1, all of the glazing is operable except the glazing on the courtyard that is only operable on the North and South ends.

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A-A

B-B

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The internal form of the building is flipped to that of option 1 with the Cafe on the East side of the building to get the morning light, and the seminar rooms on the West facade.

Testing methodology

Benchmark and Comfort Parameter settings The following benchmarks were set based on the guidelines and precedent educational buildings in this climate that aimed for low emissions buildings. CIBSE guide F indicates that school buildings should have and EUI of 190 Kwh/m2/a and university buildings an EUI of 320 Kwh/ m2/a, both of these levels seem quite high so I chose levels lower than these closer to passive haus standards at 120 Kwh/m2/a to achieve an energy efficient building.

EUI -115 Kwh/m2/a Passive haus does not provide an educational buildings emissions target for CO2, so I used precedent educational buildings and emissions targets set by the carbon trust (building the future) report which sets CO2 emissions at 65 Kg/CO2 for 2020 and 15 Kg/CO2 for 2050. The precedent examples gave a level between 50 and 75 Kg/CO2/m2/, (but with the potential to be net-zero with the use of PV panels). I have chosen to go above this level anticipating the level of cooling required in this climate and that sefaira cannot read stack and cross-ventilation methods.

CO2 - 82 Kg/Co2/m2 For daylighting CIBSE A guidelines and BREEAM recommend levels between 200 and 500 lux for well-lit classrooms and 200-300 for libraries and lecture rooms. I have chosen levels above this to provide adequate daylighting for detailed working in the studio space and seminar rooms and a comfortable light level in the cafe space Daylighting 300-750+ LUX (studio 200-500 LUX (cafe) 300-500+ LUX (seminar) For ventilation ASHRE 2019 recommends a an outside air rate of between 7.5 and 10 L/s per person for studio and classroom spaces and for lecture rooms and libraries a level of 5-7.5 L/s per person. I chose a level slightly higher than each of these (12L/s for studio and 10 L/s seminar rooms) to provide a better level of ventilation for working and maintaining thermal comfort.

Benchmarks and comfort parameters

Studio

Cafe

Seminar

Setpoint temperature

18-23℃

16-26℃

18-24℃

Occupant Density

6 m2

5 m2

4m2

Equipment Power density

10 W/m2

10 W/m2

10 W/m2

10 W/m2

10 W/m2

10 W/m2

Lighting power density

Outdoor ventilation rates per person, between 12 L/s and 10 L/s

Daylighting

300-750+ LUX

200-500 LUX

300-500+ LUX

For temperature I used CIBSE A guidelines to base the temperature ranges. For the studio a temperature range of 18-23 was selected to provide a comfortable range for most people, and following this for the seminar rooms providing a comfortable temperature range for a working educational environment.

The cafe varies slightly as there is also the option of extending the cafe into the courtyard space during the summer providing a greater temperature variation.

Setback temperature (1 hour setback ramp-up time)

16-28℃

14-28℃

16-28℃

Natural with heating and cooling

Natural with heating and cooling

Natural with heating and cooling

12 L/s

12 L/s

10 L/ s

Crack Infiltration 2 L/s m

Crack Infiltration 2 L/s m

Fan coils and central plant

Fan coils and central plant

Fan coils and central plant

8am-10pm 5 days a week

8am-10pm 5 days a week

References Butcher, K., Craig, B. & Chartered Institution of Building Services Engineers, issuing body, 2015. Environmental design : CIBSE guide A Eighth., London: Chartered Institution of Building Services Engineers.

Boubekri, Mohamed. 2014. Daylighting Design : Planning Strategies and Best Practice Solutions. Basel/Berlin/Boston: Walter de Gruyter GmbH

Ventilation Air rate Infiltration

Crack Infiltration 2 L/s m

Clark, D.H. (2013) ‘What colour is your building?’RIBA Publishing: London Butcher, K., Craig, B. & Chartered Institution of Building Services Engineers, issuing body, 2015. ECIBSE Guidlines Part L (2013)., London: Chartered Institution of Building Services Engineers.

CIBSE (2006) Chapter 1, Environmental criteria for design, in Environmental Design: CIBSE Guide A. London: Chartered Institution of Building Services Engineers ASHRE (2019) standard 62.1-2019 ‘Ventilation for acceptable indoor air quality’, ASHRE. Available at https://www.ashrae.org/technical-resources/standards-and-guidelines/read-only-versions-of-ashraestandards ASHRE (2017) standard 55.1-2017 ‘Thermal environmental conditions for human occupancy’, ASHRE. Available at https://www.ashrae.org/technical-resources/standards-and-guidelines/read-only-versions-of-ashrae-standards Carbon trust report (2015) Building the future today. Available at https://prod-drupal-files.storage.googleapis.com/ documents/resource/public/Building%20the%20Future%20Today%20-%20REPORT.pdf

HVAC system type Operating hours

8am-10pm 5 days a week

Baseline tests and results Option 2 Baseline

Option 1 Baseline

Option 2

Option 1 The energy breakdown for option 1 highlights that most of the energy is being used for lighting and equipment, also with quite a large proportion from Fans and cooling systems. The cooling required was identified in the climatic conditions section and ventilation will be looked at to see how this can be improved.

This option resulted in 121 for EUI and 108 for CO2, this is almost achieving the benchmark set for EUI (115), however the CO2 level is much higher than the benchmark. In the breakdown of this, as anticipated most of the CO2 demand was coming from the cooling requirements of the building.

Energy use

The energy breakdown for option 2 is largely similar to option , with most of the energy is being used for lighting and equipment also with quite a large proportion from Fans and cooling systems.

This option was slightly lower than option 1 for both EUI and CO2. The reason for this is the variation on glazing between the deigns with option 1 having the large skylights this increases the cooling and heating demands of the building. However this design has less glazing so the internal lighting demands and fans for ventilation were slightly higher than option 1.

Energy use

EUI 121

EUI 118

CO2 108

CO2 105

Option 1 Baseline: Plant size, Peak load, free area and Heating and cooling

Option 2 Baseline: Plant size, Peak load, free area and Heating and cooling

The main demands for the plant sizing are cooling and fans (heat rejection), this would be expected with the warm climatic conditions and providing cooling to maintain a comfortable internal temperature.

Peak loads

This can also be seen in the average peak loads with cooling demands double that of heating at 84 W/m2

34 W/m2 84 W/m2

Peak loads

The plant sizing for option 2 is slightly lower than option 1 for both cooling and heat rejection.

This is due to the design having less glazing than option 1 with less solar gain, this is also reflected in the average peak loads for the building with 77 W/m2 for cooling compared to 84W/m2 for option 1.

37 W/m2 77 W/m2

Free area

Pass

The free area passes in all zones except for the cafe, which only fails by 0.8m2 and the seminar rooms fail as the windows are quite small in this part of the facade.

Free area

Pass

However there is a very slightly higher demand for heating at 37w/m2 compared to 34 W/m2 for option 1. Again, this will be predominantly due to the glazing differences between the two designs.

For free area the two options are Marginal the same with all of the zones passing except the seminar pass rooms to the West and the Cafe to the East side only just Fail passing.

Marginal pass Fail

The sankey diagram demonstrates that the main losses from the building are from equipment and the demands of people on maintaining the internal environments. This is expected with the need for both heating and cooling systems to maintain suitable thermal comfort levels.

Roof and wall condition had slightly higher than expected losses.

Similarly to option 1, the sankey diagram demonstrates that the main losses from the building are from equipment and the demands of people on maintaining the internal environments.

The higher impact on cooling for option 2 is from roof solar gains compared to option 1 which has a smaller roof surface area.

Daylighting Baseline Option 1

Winter solstice

The initial daylighting results for option 1 highlighted that there is quite a significant variation between the winter and summer daylighting levels. During the winter solstice most of the building is below the 200 LUX threshold, except parts of the studio spaces and south facing seminar rooms.

During the spring and summer the light distribution is more evenly spread across the key rooms (cafe, studio and seminar rooms) The large skylights provide a good level of daylighting to the key rooms between 400 and 800 lux. The south facing rooms are getting less light, but this is a benefit in the warmer months reducing extra solar gains, preventing over-heating of those spaces.

Equinox

Summer solstice

Option 2 Daylighting Baseline

Winter solstice

Similarly to option 1 there is a noticeable difference between daylighting at winter and summer. The winter levels are slightly better than that of option 1 with more of the studio spaces and south facing seminar rooms getting around the 300 minimum lux level.

The initial daylighting did establish a problem with this design, during the spring and summer the studio spaces and south facing seminar rooms are getting good levels of daylight between 600-800 lux. However, the cafe and West facing seminar rooms are not getting adequate daylighting levels for working or comfort.

The design of the roof lights will need to be adjusted to improve this.

Equinox

Summer solstice

Option 1 Baseline Thermal comfort

Option 2 Baseline Thermal comfort

Under the baseline temperature comfort range of 18-24℃ most of the zones failed the operative temperature test. However most of the zones failed due to overheating rather than being too cold so more focus could be put on cooling or ventilation, with just the studios being too cold, this is likely due to the higher level of glazing for the studio spaces resulting in heat-losses.

Conversely, the overheating spaces had smaller windows and greater solar gains from the skylights, this could be more closely controlled with shading options.

Similarly to option 1, with the narrow temperature comfort range of 1824℃most of the zones (except some of the utility and circulation spaces) failed the operative temperature test. Again this is something that can be improved with the temperature ranges and ventilation methods.

It was a balance between heating and cooling causing the comfort problems co pared to option 1. For the dry bulb temperature the studio spaces passed and one of the seminar rooms, both of these spaces had operable gazing and shading from the sun.

Cafe:

Dry bulb Temperature (18-24℃) 90% of the time

Dry bulb Temperature (18-24℃) 90% of the time

Seminar room: Too warm 8% of the time

Too warm 14.5% of the time

Seminar room:

Cafe:

Too cold 4% of the time Operative Temperature (18-24℃) 90% of the time

Cafe: Too warm 22% of the time

Operative Temperature (18-24℃) 90% of the time

Studio: Too cold 12.5% of the time

Too cold 12% of the time

Studio: Seminar room: Too cold 9% of the time

Too cold 15% of the time

Baseline settings with only natural ventilation (option 1+2)

Baseline settings with mechanical ventilation off (option 1+2)

As part of the baseline methodology I wanted to look at both baseline designs with, only natural ventilation and mechanical ventilation off to see what the impact would be on the emissions and comfort levels of the building and how much energy it would take to make up the difference in comfort. With only natural ventilation on it reduced the EUI and CO2 emissions for both options significantly from 121 EUI to both options being under 100 EUI. Also with Co2 reducing that from 108 and 105 to both options being below the 94 CO2 mark.

However, this also dramatically affected the comfort levels with all of the key zones failing both the dry-bulb and the operative temperature tests by quite a long way.

Seminar:

Cafe:

Too warm 23% of the time

Too warm 11% of the time

Dry bulb Temperature (18-24℃) 85% of the time

Operative Temperature (18-24℃) 75% of the time

With the mechanical ventilation off it had an even more significant impact upon the comfort levels of the building with the worst zone failing by 56%, this test was done to understand if natural ventilation and keeping the mechanical ventilation off could be options in this design. But, with the climatic conditions this does not seem appropriate.

Turning the mechanical ventilation off does dramatically reduce EUI and CO2 emissions for both options, but the thermal comfort of the key rooms is well out of the baseline range and would not be beneficial as a working environment.

Cafe:

Seminar:

Too warm 16% of the time

Too warm 56% of the time

Dry bulb Temperature (18-24℃) 85% of the time

Operative Temperature (18-24℃) 75% of the time

Test 1 (Parallel Iterative) Temperature Temperature is selected the first test as it will have an one of the more significant impacts on the thermal comfort, emissions and energy outputs of the building.

The glazing and shading also need to be analysed more closely together so they follow this testing.

There are three temperature ranges to examine, plus the baseline. These temperature ranges were chosen based on the CIBSE A guidelines for school and university buildings, a wide temperature range of 16-26℃, a narrow range 20-23℃ and one closer to the baseline at 17-24℃ with a setback of 15-28℃). Aiming to provide a comfortable environment for working and social activity.

As expected the narrow temperature range had the highest energy load and emissions, putting more pressure on the ventilation systems to maintain such a narrow temperature range in this climate.

The 17-24℃ range proved to be the best with slightly lower emissions than the baseline, but better for user comfort as the thermal comfort diagrams on the following pages highlight.

References

16-26℃

20-23℃

Butcher, K., Craig, B. & Chartered Institution of Building Services Engineers, issuing body, 2015. Environmental design : CIBSE guide A Eighth., London: Chartered Institution of Building Services Engineers.

Clark, D.H. (2013) ‘What colour is your building?’RIBA Publishing: London Butcher, K., Craig, B. & Chartered Institution of Building Services Engineers, issuing body, 2015. ECIBSE Guidelines Part L (2013)., London: Chartered Institution of Building Services Engineers.

CIBSE (2006) Chapter 1, Environmental criteria for design, in Environmental Design: CIBSE Guide A. London: Chartered Institution of Building Services Engineers

Energy breakdown

38,210

EUI 121 CO2 108

Energy breakdown

41,863

17-24℃

EUI 121 CO2 108

Energy breakdown

40,021

EUI 121 CO2 108

Test 1 (Parallel Iterative) Temperature Option 1

Fail 5%+

Dry bulb Temperature (18-24℃) 85% of the time

Marginal fail 1-2% Moderate fail 3-4%

Operative Temperature (18-24℃) 75% of the time

Pass 0-1%

Dry-bulb and operative thermal comfort were both assessed to understand not only the ambient room temperature but how people would affect the environment and most importantly if they would be comfortable that setting.

The wider temperature range passed the dry bulb test for all of the zones with only a few colder than the set point range. For operative some of the zones failed, with the studios being too cold and the seminar room being too warm, this is due to the difference in glazing between those spaces.

For the narrow temperature range most of the zones failed the dry-bulb test and the operative comfort test, except the circulation areas as these have better ventilation and more glazing so more air is displaced than the individual rooms. Most of the zones failed because they were too warm with only the studios failing because they were too cold. This could be due to the difficulty of maintaining that temperature range in a warm climate, with the solar and radiant gains.

The range closer to the baseline performed much better for both dry-bulb and operative thermal comfort. The setback was slightly wider which mitigated the colder ranges and the warmer ranges were controlled by the ventilation systems

Setpoint 16-26

Studio: Too warm 2% of the time

Studio: Too cold 17% of the time

Setback 16-28

Setpoint 20-23

Cafe: Too warm 18% of the time

Seminar:

Setback 16-28

Too warm 26% of the time

Setpoint 17-24

Studio:

Setback 15-28

Studio: Too cold 3% of the time

Too cold 5% of the time

Test 1 (Parallel Iterative) Temperature Option 2

Fail 5%+

Moderate fail 3-4% Pass 0-1%

Similarly to option 1, The wider temperature range passed the dry bulb test for all of the zones with only a few colder than the set point range. It was also similar with the tests where the studios failed for being too cold and the lobby for being too warm, this is due to the orientation of those space, with the studios North facing and the Lobby south facing getting more solar gains.

For the narrow temperature range most of the zones failed the dry-bulb test and the operative comfort test. Option 2 performed slightly better than option1, for both of these tests, this is likely due to the difference in roof glazing and less thermal losses form the ceiling in the studio and rooms to the south.

Again, the range closer to the baseline performed better for both dry-bulb and operative thermal comfort. Option 1 performed better overall where as option 2 both of the studio spaces to the North failed the operative comfort test.

The Cafe on the dry bulb test also failed for being too warm by 6% this could be due to the different position compared to option 1

Dry bulb Temperature (18-24℃) 85% of the time

Marginal fail 1-2%

Setpoint 16-26

Operative Temperature (18-24℃) 75% of the time

Seminar:

Studio:

Too warm 1% of the time

Too cold 5% of the time

Setback 16-28

Setpoint 20-23

Seminar: Too warm 18% of the time

Seminar: Too warm 26% of the time

Setback 16-28

Setpoint 17-24

Studio: Seminar:

Setback 15-28

Too cold 2% of the time

Too cold 10% of the time

Test 2 (Parallel Iterative) Roof design for skylights, Adjusting the glazing ratio on the Northern facing roof sections Option 1 Option 1

Baseline

Option 2

Daylighting is one of the more important parts of the strategy, effecting the temperature, daylighting levels, ventilation and emissions. For this test the percentage of the north facing part of the rood skylights were varied from the baseline level at around 18% glazing for option 1 and 15% for option 2. The variants were increasing this to 25% and 50% and one reduction test to 12% for both options.

The 12% glazing option reduced the EUI and CO2 emissions to 116 (EUI) and 105 (CO2). This is an improvement on the baseline although as the lighting analysis shows most of the key rooms were not meeting the minimum 200 LUX level, only meeting this around 60% of occupied hours.

This option also increase the use of AHU slightly having a more of an impact on being able to reduce the CO2.

N

12% Skylights

25% Skylights

The 25% glazing option was selected over the baseline design for this test. Despite the 25% skylight design having slightly higher EUI and CO2 (118, 108) than the baseline the overall light distribution throughout the key rooms was better than the baseline and would provide a more comfortable and improved environment for working.

The studio, seminar rooms and cafe spaces were above 200LUX for between 80-100% of occupied hours compared to the baseline of 50-75%.

The increase in the energy breakdown largely comes from the slightly higher heating and cooling demands with more solar gains in the summer and thermal losses in the winter months.

The 50% skylight design resulted in some of the spaces becoming over-lit and the spaces on the South, East and West façades getting too much solar gains driving up the heating and cooling demands and emissions.

The 50% glazing option increase EUI and CO2 to 130 and 119, which represents quite a big increase from the baseline and is not beneficial to the user comfort.

References Boubekri, Mohamed. 2014. Daylighting Design : Planning Strategies and Best Practice Solutions. Basel/Berlin/Boston: Walter de Gruyter GmbH Clark, D.H. (2013) ‘What colour is your building?’RIBA Publishing: London CIBSE (2006) Chapter 1, Environmental criteria for design, in Environmental Design: CIBSE Guide A. London: Chartered Institution of Building Services Engineers

N

50% Skylights

Test 2 (Parallel Iterative) Roof design for skylights, Adjusting the glazing ratio on the Northern facing roof sections Option 2

Baseline

Daylighting is one of the more important parts of the strategy, effecting the temperature, daylighting levels, ventilation and emissions. For this test the percentage of the north facing part of the rood skylights were varied from the baseline level at around 18% glazing for option 1 and 15% for option 2. The variants were increasing this to 25% and 50% and one reduction test to 12% for both options.

The 12% glazing option reduced the EUI and CO2 emissions to 116 (EUI) and 105 (CO2). This is an improvement on the baseline although as the lighting analysis shows most of the key rooms were not meeting the minimum 300 LUX level, only meeting this around 60% of occupied hours.

This option also increase the use of AHU slightly having a more of an impact on being able to reduce the CO2.

N

12% Skylights

The 25% glazing for option 2 created an interesting daylighting result with the North half of the building getting between 80-100% of the minimum LUX level but some of the seminar rooms and South-facing rooms only meeting around 50% of the daylighting requirements. This is due to the glazing being focused to the North part of the roof.

25% Skylights

For the emissions 25% glazing did result in quite a large increase in EUI and CO2 from the baseline level, increasing to 127 and 116. The overall energy use also increase by 3000kwh, with higher loads from the HVAC system.

With 50% glazing it was quite clear that the studio and seminar spaces were over-lit, getting 100% over 200 LUX for occupied hours. This would not be a comfortable environment for working with excessive solar gains and glare. The emissions also dramatically increased to 147 EUI and 135 CO2 and almost 50,000 kwh/a.

This level of emissions would be due to the higher demands on the HVAC system, pumps and fans and is not a suitable option to take forwards. In this case the baseline proved to be the most appropriate balancing adequate daylighting levels for comfort and good energy intensity.

Option 1

Option 1

References Boubekri, Mohamed. 2014. Daylighting Design : Planning Strategies and Best Practice Solutions. Basel/Berlin/Boston: Walter de Gruyter GmbH Clark, D.H. (2013) ‘What colour is your building?’RIBA Publishing: London CIBSE (2006) Chapter 1, Environmental criteria for design, in Environmental Design: CIBSE Guide A. London: Chartered Institution of Building Services Engineers

N

50% Skylights

Test 3 (Parallel Iterative) Shading options Design 1

Shading is the final of the Parallel test and is closely related to the skylight glazing tests.

The shading tests look at a range of three options for shading and the baseline, which is just the analysing existing shading on the design.

N

The tests are adding operable shading on the skylights at lengths of 3m, 2m and 1m.

The effects of this are analysed in terms of daylighting and emissions. Since the shading is operable thermal comfort could be varied by the user and is therefore not necessary to look at for this set of tests.

The 2m shading option seemed to be the most effective, as the daylighting analysis shows it reduced the intensity of light coming from the skylights compared to 1m of shading, but didn’t block out the light like the option of 3m shading did.

The 2m of shading also had the lowest emissions at 112 EUI and 102 CO2, slightly lower than the baseline for both. This is largely due to reductions in cooling demands as the solar gains can be controlled.

Overall the shading didn’t change the emissions and overall energy use by that much, having most of an effect on the daylighting levels.

The reason for this is the design strategy for the building, emphasising on providing shading from the beginning and the baseline design seems to do this quite effectively. The facade glazing is largely protected with the existing design, its only really the skylights that require additional shading to improve daylighting levels.

3m operable shades

2m operable shades

1m operable shades

Test 3 (Parallel Iterative) Shading options Design 2 A similar pattern occurred for option 2 with the 3m of shading blocking out most of the light and actually increasing the base emissions for EUI and CO2. 1m and the 2m of roof shading appeared to be the best options with both having the same EUI and CO2 emissions levels. However the 1m of shading improved the interval lighting conditions whilst 2m of shading made the studio spaces and seminar rooms slightly darker.

Overall this option does not provide adequate daylighting levels to take forwards, despite the overall EUI and CO2 emissions being better for this deign (due to minimising solar gains and having a tight thermal envelope) the daylighting does not meet the benchmark levels set and would not be adequate for working, studying or socialising.

N

Based on the three previous tests I decided to take option 1 forwards into the iterative testing part of the methodology. This was predominately due to option 1 having more desirable thermal comfort and daylighting levels, option 2 often performed better in terms of emissions and energy use, however the lighting conditions in the seminar rooms and studios were either over-lit or under-lit (option 1 found a good balance of well-lit space) and it failed many of the operative thermal comfort tests for all of the set-point temperature ranges. Option 1 has a good thermal comfort criteria and has a good level of daylighting cross all of the key space which can be controlled throughout the seasons with the 2m of operable shading.

3m operable shades

2m operable shades

1m operable shades

Test 4 (Iterative) Ventilation (Option 1 taken forwards)

5 L/s 10 L/s 20 L/s

Ventilation is important for maintaining user comfort and can have a n impact upon the overall energy breakdown on the building, as well as EUI and CO2 emissions.

5 L/s per person

10 L/s per person PRODUCED BY AN AUTODESK STUDENT VERSION

PRODUCED BY AN AUTODESK STUDENT VERSION

PRODUCED BY AN AUTODESK STUDENT VERSION

ASHRE (2019) standard 62.1-2019 ‘Ventilation for acceptable indoor air quality’, ASHRE. Available at https://www.ashrae.org/technical-resources/standards-and-guidelines/read-only-versions-of-ashraestandards

PRODUCED BY AN AUTODESK STUDENT VERSION

CIBSE (2006) Chapter 1, Environmental criteria for design, in Environmental Design: CIBSE Guide A. London: Chartered Institution of Building Services Engineers

PRODUCED BY AN AUTODESK STUDENT VERSION

References

PRODUCED BY AN AUTODESK STUDENT VERSION

PRODUCED BY AN AUTODESK STUDENT VERSION

As expected 5 L/s had a low level of emissions and total energy use with a reduction from the baseline in EUI and CO2 to 105 and 97, alongside reducing the energy breakdown, mostly through reductions in cooling.

However, such a low air rate can be uncomfortable and cause drowsiness if too many people are in the room at a time.

For this test the baseline levels of 12 L/s in the studio and Cafe and 10 L/s in the seminar rooms proved to be the most comfortable for the level of emissions

PRODUCED BY AN AUTODESK STUDENT VERSION

I have chosen to test levels above and below that benchmark, analysing 5 L/s, 10L/s and 20 L/s to see which has the greatest impact upon emissions, energy use and user comfort.

20 L/s per person

PRODUCED BY AN AUTODESK STUDENT VERSION

PRODUCED BY AN AUTODESK STUDENT VERSION

PRODUCED BY AN AUTODESK STUDENT VERSION

PRODUCED BY AN AUTODESK STUDENT VERSION

The tests here were conducted based on the ASHRAE 2019 standard for outside air rate per person, recommending a level between7.5 and 10 L/s for classrooms.

36% of total energy demand

Test 5 (Iterative)

Assign renewables, Photovoltaic panel on the roof For this design option there is 44.8m2 of space available to each of the roof ‘pyramids’ that are south facing and does not affect the light entering the building or the level of shading, since the skylights are North-facing only.

For this test it has been set at three levels 45m2 representing one section of the roof 90m2 covering half of the roof and 180m2 covering all of the South-facing part of the roof.

As the response cure shows the CO2 emissions and EUI decrease in tandem with the increase in the area of photovoltaic panels and the renewable energy generated.

Photovoltaic area response curve

Effect of photovoltaic area on EUI and CO2 for design option 1

The diagrams below highlight what each of the tests would look like on the roof design, along with the renewable energy generated. Test 3 (180m2) was selected as the best option providing 98% renewable power generation for the building and significantly reducing both EUI and CO2 emissions to -56 and -78.

45m2

N

90m2

180m2

EUI 73

EUI 30

EUI -56

CO2 60

CO2 14

CO2 -78

Preferred Option + Conclusions Free area, energy breakdown and plant sizing

Plant sizing Baseline

Comparing the final output to the baseline there were some improvements for free area, energy breakdown and plant sizing.

For the free area the roof glazing was increased to 25% from the baseline of 18%, this allowed the East-facing seminar rooms to pass the free area test. This will improve ventilation levels and thermal comfort alongside improvements in daylighting from the larger skylights.

The only zones that failed were the utility and storage rooms that don’t have or require any glazing.

For the energy breakdown, it is clear that fans are having a fairly consistent impact on both the baseline and the preferred option. For the preferred option there was a reduction in heating use and a small reduction in cooling compared to the baseline.

The adjustments made to the temperature ranges and glazing will have improved the control of the interval temperatures, therefore there is less of demand on the heating and cooling systems seasonally.

Preferred option

This is also reflected in the overall plant sizing with the heating reducing by almost half from 30.2 kWh to 16 for the preferred option. There was also a slight reduction in cooling demand from 64 to 56 kWh, again due to the increase in glazing improving the free are and ventilation, reducing the cooling demand., Air handling remained the same as the baseline ventilation rate was carried forwards. It is useful to show the energy breakdown throughout the year to analyse which areas are hang the most impact a, as expected the heating and cooling follow the seasonal patterns with more cooling required in the summer ad more heating in the winter.

Equipment and lighting were fairly consistent along with the fans and the pumps had more energy use in the summer as the water-cooled cooling system was required to maintain the set-point temperature ranges.

Energy breakdown

Free area Baseline

Baseline

Preferred option Pass Marginal pass Fail

Preferred option

Preferred Option + Conclusions Daylighting and Thermal comfort

Studio

Cafe

Analysing the comfort parameters the chosen option performed much better than the initial baseline for both daylighting levels and thermal (dry-bulb and operative comfort) comfort levels

For the operative tests some of the seminar rooms failed because they were slightly too warm. P04 was identifies as having excessive solar gains that make it overheat compared to the other seminar rooms.

Adjustments could be made to add additional operative glazing in this space.

Courtyard Seminar Lobby

Setpoint 17-24

Both of the studios had a good level of lighting during both the winter and summer, with around 400 lux in the winter and between 600 and 800 in the summer both of these levels are within the benchmark levels.

For dry-bulb the North-West studio was slightly too cold but this is due to the higher glazing level compared to the other façades, providing better daylighting for detailed work.

Studio

Summer solstice

For daylighting the key spaces (cafe, studios and seminar rooms) had between 75-100% of daylighting levels above the minimum 200 LUX. The south-facing rooms had lower light levels but this is due to them having smaller windows and shading to reduce solar gains in the summer months, preventing overheating.

For thermal comfort the final output performed better than the baseline with most of the rooms passing both the dry-bulb and the operative thermal comfort tests. The 17-24℃ level proved to be the most appropriate for and thermal comfort and reducing emissions slightly.

Avarage annual daylight

Winter solstice

Setback 15-28 Studio:

Studio:

Too cold 3% of the time

Too warm 2% of the time

Seminar: Too warm 7% of the time

Seminar:

Dry bulb Temperature (17-24℃) 80% of the time

Too warm 4% of the time Operative Temperature (17-24℃) 75% of the time

Preferred Option Conclusions Comparing baseline and final outcome

Baseline

Final option

Compared to the baseline the Final design outcome performed significantly better for EUI and CO2 reducing the emissions form an initial 121kWh/ m2/ and 108 kg/co2 to negative 56 kWh/m2 and negative 78 kg/co2.

This means that the final design exceeded the set benchmark levels of 115 EUI and 82 CO2. Becoming carbon neutral as well.

The baseline actually performed better than I initially expected almost meeting the benchmark for EUI without making any changes. This is likely due to the design of the building as described in the shading tests, the initial design already had a good level of shading and suitable glazing for each part of the façades, this meant that excessive solar gains were reduced and less energy needed to be used on cooling. However it was further away from the CO2 target of 82 kg/co2 only achieving 108 kg/co2 for the baseline, this was due to the climatic conditions and the difficulty of maintaining the temperature so the main loads came from the HVAC system, heating, cooling and the fans handing an impact on this level.

For the energy breakdown, the decreases mainly came through reducing heating demands and the fans, the internal energy load and the cooling largely stayed the same. This again is due to the climatic conditions and being able to maintain the benchmark comfort parameters maintaining the load on cooling.

Overall there was a 10% reduction in the total energy use between the baseline and the final outcome. With more significant reductions of 146% and 172% for EUI and CO2, this is mostly down to the PV panels reducing the energy and carbon footprint of the building.

-10%

EUI 121 CO2 108

-146%

-172%

EUI -56 CO2 -78

Preferred Option Conclusions + Design changes Overall, I think that the design was successful in being able to exceed the emissions benchmarks and meet the comfort parameters. Option 1 proved to be more adequate for the internal comfort conditions such as daylighting and thermal comfort compared to option 2, despite option 2 having slightly better emissions outputs. The methodology was successful in the way it was ordered putting glazing and shading next to each other so they could be analysed more closely and placing the PV as the last test was also useful as it did not have an impact upon the other tests and could not affect the comfort or daylighting levels.

It could have been interesting to take both options all the way to the PV stage as option 2 had a larger roof surface area so would have probably performed better than option 1, in terms of emissions. Further tests could have been conducted for the HVAC system type as this was not explored as part of the methodology and could have had a greater impact on reducing the emissions whilst maintaining thermal comfort parameters, this was also the main source of energy and emissions for the building so could have been explored further.

It could be important to note that prior to assigning the PV panels the design only achieved an EUI of 112 and CO2 level of 102, this does represent a decrease from the baseline values but is only a slight decrease, I would have expected a slightly larger reduction. However, through improving the thermal comfort this added an extra load onto the HVAC system which was already making up most of the energy load for the building alongside adding extra roof glazing slightly increasing the heating load.

This testing process has highlighted that it can be more difficult to achieve the emissions benchmarks without compromising on the internal comfort conditions and daylighting levels, this returns to the initial baseline tests where I explored how the building would perform with only natural ventilation and with the mechanical ventilation off. These tests proved that it can be quite simple to significantly reduce emissions, but not without compromising on the comfort parameters with most zones in both tests failing by quite a large margin. The final option here aims to balance slightly higher emssions with good comfort parameters for the function of the building.

In terms of sefaira as a tool it can be useful for getting a quick picture of the overall building performance and how this can be improved through various tests and techniques as well as design adjustments. Sefaira is good for providing an energy breakdown of the whole building alongside individual zones to get an idea of any specific areas having a greater impact on the buildings performance, this was a useful way of learning about how zones can be separated and analysed more closely, for example one of the seminar rooms (P04) on option 1 had a much higher peak load than the other seminar rooms of the same size, in turned out that it was coming from solar gains and the design could then be adjusted. But this was useful for seeing how small rooms can have an impact on the building performance and identifying problems with the deisgn.

Drawbacks of Sefaira include that it cannot analyse stack or cross ventilation, which was something I was considering in the strategy for this design and this could have reduced the overall cooling demands and CO2 emissions.