ASHISH KHEMCHANDANI Building Simulation works
www.ashishkhemchandani.com
(267) 475-4728 ashishkh@design.upenn.edu 5121 Pine St, Floor 3 Philadelphia, PA, 19143 www.ashishkhemchandani.com
ASHISH KHEMCHANDANI Architectural + Environmental Designer
Chautaqua Institute
Performance and Design project, the University of Pennsylvania (2016)
Orientation and Shade study
Building performance simulation and optimization project (2015)
The Nuthatch Hollow
Performance optimization for a registered Living Building project (2017)
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01
local vegetation
A
microclimate
solar chimney F
black paint
F
PV panels E
Chautaqua Institute, Arizona
Performance and Design project, University of Pennsylvania (2015-16) Besides understanding the fundamentals of Environmental design, MEBD helped link the relation between strategizing environmental parameters and, rather importantly, to quantify the research into a real-time architectural experiment. The following pages showcase some examples of the exploration through the course of the experiment and an attempt to quantify those explorations. The New Chautaqua institute was an experimental studio brief which focused on applied research of environmental design strategies using parametric design tools and simulation strategies to quantify sustainable design in various climatic zones of the United States, in this case, in the Hot and Arid climate of the Phoenix region in Arizona.
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D
floor cooling vents
fans a
valve to prevent reverse draft
xeriscaping with local vegetation
skylight
A
Outside air harnessed into the courtyard with an opening in the mass on the wind-ward side
D
Floor-vents induce the cooled air for indoor ventilation and adaptive comfort
B
Evaporative cooling features such as water-body and fountain cool down the air creating a cool microclimate
E
Solar chimney heats the warm, risen air using black paint and glass and expels it to induce air-exchange
C
Periodic inlets use fans and solar chimneys to harness the cooled microclimate air into the indoors to induce ventilation
F
Valves in the chimney prevent reverse draft of the hot air, or of the outside air
skylight
C
B C
C
C D
and sprinklers
upper floor inlets inlet to harness the cool micro-climate air
water body and fountain for evaporative cooling
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Radiation & Daylighting: Sparse cloud cover and high radiation levels mean there’s good daylighting and solar energy potential, but all glazing need to be shaded at all times to prevent radiative heat gain. Perforated shade over the courtyard traps the cooled micro-climate air but allows the stale heated air to escape via stack effect.
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2
Natural Ventilation: Natural ventilation can reduce air conditioning in warm but not very hot days, if combined with some passive cooling techniques and shade. Opening in the mass in the windward side can harness oncoming wind into the courtyard.
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Evaporative cooling & Local Vegetation: Low humidity ratios allow for evaporative cooling strategies to help reduce the air temperature and induce comfort. Treated courtyard and stack effect to induce ventilation can aid both the indoors and outdoors. Local plantations can help shade walls and improve outdoor micro-climate.
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Narrow Floor Plans: Long and narrow floor plan would facilitate cross ventilation, careful openings on the wind-ward side would harness treated microclimate air. Fan-driven ventilation can bridge the difference during the hottest months.
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B A
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D
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9 1
Ground Floor Plan
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1 Lobby 2 Director and staff offices 3 Laboratory-1 4 Laboratory-2 5 Seminar room
F irst Floor Plan
6 7 8 9 10 11
Exhibition + Retail Xeriscape Water fountain Staff work-spaces Archives Library
C
Second Floor Plan
A Angled vertical fins B Cool air channels (open during summer) C Solar chimney D Mechanical sliding windows (Glazed faรงade)
Partial detail
C
A
A
B
B
Summer cross section
Winter cross section 7
Thermal and visual comfort studies: exploring various shading strategies and parameters
(tools: EnergyPlus using Honeybee for Grasshopper platform, Radiance using Diva and Honebee for Grasshopper platform, Design Explorer) Base case
Ideally shaded case
A Black box case with no open-
ings/ glazing
B Case with maximum glazing ratio
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Box shades + blind parameters
2 Vertical shading parameters
(SW=60%, NE=90%)
Single story height
ng
i uild
B
Adaptive Comfort:
pth
de
38.38%
Adaptive Comfort:
13.76%
sDA:
100%
SW: WWR: 80% NE: WWR: 90%
Adaptive Comfort:
38.38%
sDA:
94.64
SW: WWR: 90% NE: WWR: 90%
Adaptive Comfort:
50.98%
Various box shade parameters
. . . Various vertical shading fin parameters
. . . 8
sDA:
79.64
Spatial Daylight Autonomy (sDA) 100.00 90.00 80.00 70.00 60.00 50.00 40.00 30.00 20.00 10.00 00.00
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4.
1.
3.
1.
Aluminium vertical shades (fins)
2.
2. Triple-glazed units with 12mm gaps 3. Curtain wall 4. White paint+plaster
1.
5. Cement Stabilized adobe brick lay-
er + Cellulose insulation + Adobe brick layer
To determine the shading conditions most ideally suited for optimum annual adaptive comfort without the use of systems, several hundred simulations were run for a single bay within the building were run. Using Design Explorer, it was possible to find the alternative that works best in terms of thermal comfort and daylight. Check out the design explorer link here, and cycle through a sample simulation set.
Angled Vertical fins Of the box shades and angled fins, it was found after running hundreds of experiments that a continious array of fins 1.5m (≈5ft) in length and 1.33m (≈4’5”) apart gave the highest level of thermal comfort with the smallest compromise in daylight autonomy, while also controlling glare. This essentially gave a length to distance ratio of 1.1, if the fins were to be made smaller or closer together. The next two pages simulate the results in a larger zone while finding more accurate parameters, and simulating other passive strategies like evaporative cooling and ventilation. 9
1
Base case (no shading/ventilation and default double glazing) (tools: EnergyPlus and Radiance using Honebee platform)
Degrees from target to reach adaptive comfort range
Adaptive Comfort % by unit area
Adaptive comfort level: 16.08 to 18.18%
Adaptive comfort level:
Degrees from target range: 6.94°C to 8.00°C Annual solar exposure (Graph indicates too much daylight exposure)
Daylight Glare potential (cd/m2) High
Sep. 1200hrs
Daylight autonomy
17.34%
Dec. 1200hrs
0.50
sDA: 100.00
0.62
sDA: 100.00
Energy loads - Base Case 28000 21000
Storage (Monthly) Cooling (Monthly) Infiltration (Monthly) People (Monthly) Lighting (Monthly) Equipment (Monthly) Solar (Monthly) Heating (Monthly)
14000 7000 00
Energy (kWh)
-7000 -14000 -21000 -28000
Jan
Feb
Mar
Apr
May
Jun
Jul
Site EUI: 10
Aug
Sep
Oct
Nov
Low
Maximum DGP: 0.62
Dec
778.88 kWh/m2 (241.95 kBTU/ft2)
Simulation Parameters: • • •
SW Glazing to Wall Ratio (GWR) @60%, NE GWR @90% with no shades Default glazing material (clear DGU with 12mm airgap) No natural ventilation
Observations: • • • •
The maximum energy loads are accounted for by the required Cooling and Solar heat gain in a conditioned building. Average normalized adaptive comfort percentage @17.34 with adaptive comfort range from 16.08 to 18.18% (ASHRAE standard 55) 100% Daylight Autonomy but UDLI>2000 (excess Annual Solar Exposure) in NE and SW directions due to lack of shade and glazing Daylight Glare Potential (DGP) from September to December ranges from 0.5 to 0.62 (Intolerable glare)
Base case+shading+materials (ASHRAE standard materials and high-performance glazing) (tools: EnergyPlus and Radiance using Honebee platform, LBNL Therm and Window) Adaptive Comfort % by unit area
Adaptive comfort level: 30.10 to 34.73%
Degrees from target to reach adaptive comfort range
Adaptive comfort level:
Degrees from target range: 0.81°C to 1.47°C Annual solar exposure (Graph indicates too much daylight exposure)
32.66%
Daylight Glare potential (cd/m2) High
Sep. 1200hrs
Daylight autonomy
Dec. 1200hrs
0.22
sDA: 84.62
0.21
sDA: 84.62
Energy loads - Shaded case
Simulation Parameters: •
21000
Storage (Monthly) Cooling (Monthly) Infiltration (Monthly) People (Monthly) Lighting (Monthly) Equipment (Monthly) Solar (Monthly) Heating (Monthly)
14000 7000 00 -7000 -14000 -21000 -28000
Jan
Feb
Mar
Apr
May
Jun
Jul
Site EUI:
Aug
Sep
Oct
Nov
Low
Maximum DGP: 0.22
28000
Energy (kWh)
2
Dec
318.47 kWh/m2 (93.98 kBTU/ft2)
• •
Change glazing parameters to high-performance Triple-Glazed units with Low-e coating using the LBNL WINDOW tool Change wall and roof materials to ASHRAE standard-55 materials for climate zone-02 Add shades using parameters from the previous simulation i.e. SW @angle 69°, NE @angle 306°
Observations: • • •
Average normalized adaptive comfort percentage @32.66 with the adaptive comfort range from 30.10 to 34.73%(ASHRAE standard 55) sDA 300 lux @ 84.62%, excess UDLI controlled. Daylight Glare Potential (DGP) from September to December ranges from 0.20 to 0.22 (Imperceptible glare) 11
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Ventilation+Evaporative cooling+Courtyard shading
(tools: Ansys fluent for CFD; EnergyPlus weather tool for simulating evaporative cooling in the EPW file) Natural wind-flow in the courtyard
Temperature differential between the inlet and the solar chimney
4.46e-01 4.23e-01 4.01e-01 3.79e-01 3.57e-01 3.34e-01 3.12e-01 2.90e-01 2.67e-01 2.45e-01 2.23e-01 2.01e-01 1.78e-01 1.56e-01 1.34e-01 1.11e-01 8.91e-02 6.68e-02 4.46e-02 2.23e-02 0.00e+00
0.15 m/s
0.15 m/s
The diagram indicates the temperature of the ventilating air. The temperature at the inlet is as much as the average wet bulb temperature in the average hottest week
Wind Velocity (m/s)
Wind velocity in the region and courtyard at 5m height
Adaptive comfort level range: 46.88 to 55.33%
Degrees from target range: 0.41°C to 0.80°C
Energy loads - with shading and evaporative cooling 28000 Storage (Monthly) Cooling (Monthly) Infiltration (Monthly) People (Monthly) Lighting (Monthly) Equipment (Monthly) Solar (Monthly) Heating (Monthly)
14000 7000 00
Energy (kWh)
-7000 -14000 -21000 Feb
Mar
Apr
May
Jun
Jul
Site EUI: 12
Aug
Sep
Oct
Nov
Dec
102.21 kWh/m2 (32.4 kBTU/ft2)
Adaptive comfort level:
50.94%
Simulation Parameters: •
21000
Jan
The diagram indicates the velocity of the ventilating air induced purely using the temperature differential in between the inlet and the outlet of the olar chimney
Degrees from target to reach adaptive comfort range
Adaptive Comfort % by unit area
-28000
Interior wind flow through the inlet due to the solar chimney
• •
Edit the EPW file to reflect evaporative cooling @50% efficiency, using the formula DT-[(DT-WT)*0.5], where DT = Dry-bulb tenperature and WT = Wet-bulb temperature to find the corresponding new temperature and replace the Dry-bulb temperatures greater than 30° with the corresponding new temperatures to simulate evaporative cooling Completely shade the courtyard using the building as context, and the shade on top Turn ventilation on using stack effect
Observation: •
Adaptive comfort rises to almost 51% without the use of any mechanical systems with the adaptive comfort range from 46.88 to 55.33%. the degrees from target falls from 8.0° C to a maximum of 0.8° C, while glare falls to a maximum of 0.35 (imperceptible glare) from 0.62 (intolerable glare) in the base case.
Summary As it is well understood, sustainable design is more than just adding solar panels and shading mechanisms as surface add-ons. Environmental performance and sustainability in this project, as should be, was considered as one among the important preliminary criterion to match while drawing the first line on the design-board. That is rave. As important as it is to understand and consider the fundamentals of climate-responsive design during the entire design process, it is also important to quantify, document and optimize the building performance based on the generated data to design a building upto its fullest performative potential. Building energy modeling and simulations help there. The comfort simulations with shading optimizations helped determine the right kind of shade that met the architectural criterion. The application in a larger zone within the building was an experiment to see how well the shading optimization experiments worked, while the CFD simulations helped simulate the airflow pattern in the courtyard and the building interior. The CFD and evaporative cooling helped realize how much the simple strategy could help improve occupant thermal comfort in the particular climate zone. The building successfully achieved over 50% comfort conditions annually without the use of any mechanical systems, which in theory makes it eligible for the LEED platinum rating. If the deficit is fulfilled using on-site energy generation, the building could be made compliant with the rigorous Passivhaus standard requirements. By no means is the project optimal, it had the potential to be taken much further. The building fell short of achieving net-zero performance. It was observed that the application of dynamic shading device improved the daylight and comfort conditions substantially but due to time constraints, the numerous simulation runs required to determine the ideal dynamic shade parameters weren’t carried out. Nonetheless, this was still a successful experiment to see how this approach can help design highly performative buildings, and to realize the magnitude of the difference that the optimization can make on the ultimate performance of the building.
Site EUI 71.7
54
32
32.4
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deficit borrowed from the grid 13.4
n ld eng rgy d o s) uir s) Go t) ildi pe ne 15 e q t u D E e t n a r b l E r nt a in na cil 20 ne poi ce /Tem (LE mpli um 8 po o e i I n ffi t i x g n D i t U o 1 a ou O n c E EE Pla pto rgy ern ge oe ing ne e (3 L Int ode C d ED for u l era in Ph E i E v t L t( A C Bu si n me The building Energy performance compared to the average office building in the region (source: Building Performance Database), International Energy Code and LEED Platimum requirements 13
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Cape town
Orientation and Shade study for Thermal and Visual comfort
Building performance simulation and optimization project, University of Pennsylvania (2015-16) The project was the thermal and visual comfort optimization of an unconditioned space using ventilation, shade and daylighting strategies in Capetown, South Africa. The purpose of this project is to provide maximum hours of comfort for an indoor space with no heating and cooling system by redesigning the faรงade. A good design should be well daylit and provide maximum possible hours of thermal and visual comfort for the occupants during the occupancy of the building.
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Area: 32 m2 Glazing to wall ratio (glazed wall): 0.72 Occupancy hours: 9am - 5 pm (Office)
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Exterior climate data and UTCI
The base-case
12.45°c
Average cold-week drybulb temperature (June.8June.14)
27.5°c
Average hot-week dry-bulb temperature (Dec.1-Dec.7)
57.35%
Annual Predicted Mean Vote (PMV) comfort without the use of systems
65.8%
Average hot-week RH (Dec.1-Dec.7)
Too hot Comfortable Too cold
42.65
2492.54
Percentage of time the outdoors are uncomfortable
Total load
Total Cooling load: 1349.27 Total Heating load: 8.13 Total Lighting load: 1095.54
•
24m/s
maximum wind speed
1128.72
Maximum global radiation from due North
• •
Cape town falls under the international zone-4 as per ASHRAE standard 90.1-2007. It experiences dry, warm summers and mild, humid winters. With internal heat gain, 77% of the hours in a building can fall within the comfort range. The outdoors are comfortable 57.35% time of the year by default, without any design intervention. For the selected indoor space, the default thermal and lighting loads amount to 2492.54 kWh with the glazed facade facing SE 15
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Studying the effect of orientation on thermal and lighting loads
3276.22
3497.26
16.67%
16.67%
Total Cooling load: 2346.33 Total Heating load: 0.0 Total Lighting load: 929.22
Total Cooling load: 2451.79 Total Heating load: 0.20 Total Lighting load: 1045.27
2492.54
4453.37
41.67%
0%
Total Cooling load: 1349.27 Total Heating load: 8.13 Total Lighting load: 1095.54
Total Cooling load: 3360.10 Total Heating load: 0.0 Total Lighting load: 1093.27
2076.54
3882.5
50%
0%
Total Cooling load: 961.74 Total Heating load: 12.33 Total Lighting load: 1102.47
Total Cooling load: 2744.18 Total Heating load: 0.0 Total Lighting load: 1138.32
2406.89
4448.49
33.33%
0%
Total Cooling load: 1346.38 Total Heating load: 9.85 Total Lighting load: 1050.66
Total Cooling load: 3346.85 Total Heating load: 0.0 Total Lighting load: 1101.64
Total load
PMV comfort
Total load
PMV comfort
Total load
PMV comfort
Total load
PMV comfort
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Total load
PMV comfort
Total load
PMV comfort
Total load
PMV comfort
Total load
PMV comfort
Loads vs Direction of Glazing
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Designing the shade for optimum comfort and daylighting A (No shade)
%UDLI>300 lux
50%
PMV comfort percentage
98.3%
Spatial Daylight Autonomy (300 lux)
45°
%UDLI>2000 lux
B
45° %UDLI>300 lux
Upon changing the orientation of the building, or (alternatively) changing the direction of the facade to be glazed, the energy loads can be reduced by 53.3% compared to the worst-case alternative and 16.7% compared to the base case. Here, the ideal case is a South glazed facade, a 45° clockwise rotation to the base case. Here, the loads are calculated considering the mechanical systems on and the comfort is calculated without.
54.33%
PMV comfort percentage
97.06%
Spatial Daylight Autonomy (300 lux)
%UDLI>2000 lux
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Check Daylight Glare Potential 12 noon Radiation
Spatial Daylight Autonomy (300 lux)
%UDLI>2000 lux
1479.55
21 December
87.5%
0.34
Total Energy loads in kWh
w/o shade
maximum Glare Potential
D
•
%UDLI>300 lux
41.67%
82.35% 18
Imperceptible: <35% Perceptible: 35-40% Disturbing: 40-45% Intolerable: >45%
with shade
0.30
maximum Glare Potential
Shading helps control the indoor temperature during the warm summer months i.e. from September till March. But the added comfort in summer due to shading comes at the cost of colder indoor temperatures during winter. Therefore, excessive shading reduces comfort. This tradeoff makes it unfeasible to achieve 100% comfort through shading. At 0.34, the glare without shade falls within the Imperceptible glare range therefore, further reduction of glare was not necessary. The shades did however reduce the DGP down to 0.30.
Conclusion:
PMV comfort percentage
Spatial Daylight Autonomy (300 lux)
â&#x20AC;˘
Radiation
21 September
21 June PMV comfort percentage
21 September
66.67%
21 December
%UDLI>300 lux
Glare
21 June
Glare
C
%UDLI>2000 lux
Using the right shade type and by optimizing the orientation of the glazed facade, it was feasible to reduce the thermal loads of the building by 40.6% and increase PMV comfort by 25% while controlling excess daylight.
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‘Nuthatch Hollow’, a registered ‘Living Building’ Environmental Sciences Lab Daylighting, Thermal Comfort, Shade and Glare optimization, Ashley McGraw Architects (2017)
The Environmental Sciences Laboratory at the Binghamton University is a registered ‘full living building’ designed to fulfill all the requirements of the rigorous Living Building Challenge introduced by the International Living Futures Institute. Most significantly, the project must be Net-positive in terms of Water and Energy and must not contain ‘Red-listed’ materials that can be potentially harmful to the Environment or inhabitant’s health.
more info: http://envi.binghamton.edu/
Significant in-depth research was carried out to meet the projects material requirements and full scale energy-modelling, daylighting and thermal comfort studies were carried out to optimize the performance of the project and meet the LBC requirements. 19
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The three different parameters to optimize
Placement of the volumes Composting toilet chamber
Existing retaining wall
Glazing to wall ratio
Vegetated green roof
Composting toilet chamber
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Shading devices
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Exploring the parameters to optimize. Click here to explore all options
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Whole building daylight study
sDA: Multi-purpose room: 81.89% Laboratory: 74.30%
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Checking point-in-time illuminance for the finalized option
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Balancing Daylight Autonomy with Annual Glare Factoring wall-thickness, optimizing shade to balance daylight while controlling glare: The wall thickness, reflectance of indoor materials and visible transmittance of the glazing was assigned to increase the accuracy of simulations and further optimization. The shade designed to balance daylighting with annual glare, keeping the glare from South to a minimum.
01 - Adding wall thickness and assigning reflectance to the indoor surfaces
03 - Increasing shade and tapering the window sill and heads to increase daylight
Alternative-01
Alternative-02 Alternative-04
Earlier iterations for optimizing various design options
Alternative-03
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02 - Adding shade to control glare, and inputting the visible transmittance of glazing for a more accurate outcome
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04 - Distributing shade to further reduce glare
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. . .