How can the thermal environment of an office space be improved by passive and active cooling strategies?

PROJECT INFORMATION

Graphic Name: How can the thermal environment of an office space be improved by passive and active cooling strategies?

Submitted by: Johannes Bracke

Firm Name: Baumann Consulting

What tools did you use to create the graphic?

  • IES

  • Excel

  • Power Point

What kind of graphic is this? Matrix of spatial heatmap and scatter plot

Primary Inputs: Building geometry, location, building envelope specs (U-Value, SHGC, internal gains), mechanical systems (ventilation system, chilled ceilings)

Primary Outputs:

Room air temperature, operative room temperature.

GRAPHIC INFORMATION

What are we looking at?

The graphic compares the indoor air temperature for selected office spaces before and after the implementation of optimization measures. The upper six visualizations show a colored representation of the room air temperature for three different times on a summer day in August. The scatter plot below shows the room air temperature as a function of the outside air temperature. 

How did you make the graphic?

IESVE was used to create the 3D building model. Detailed room models were created for selected office spaces, including the internal loads, cooling equipment and control of the external shading device. A dynamic thermal simulation was then created for the designed and optimized technical parameters. As a result, the room air temperature for the office spaces was calculated over the course of the year. I exported the perspective images from IESVE and created the scatter plots in Excel. I then combined the information in Power Point.

What specific investigation questions led to the production of this graphic?

  • How can the thermal comfort of the selected office spaces be improved?

  • Which passive and/or active measures lead to an improvement of the thermal comfort?

How does this graphic fit into the larger design investigations and what did you learn from producing the graphic?

The results of the study show that the installed cooling equipment is significantly undersized. Furthermore, the installed shading device does not effectively prevent the penetration of solar radiation. Overall, this leads to massive thermal comfort issues (high room air temperatures as well as high temperatures of the glass surfaces). The installation of an optimized external shading device and additional cooling capacity allows the room air temperatures to be kept within an acceptable range.

What was successful and/or unique about the graphic in how it communicates information?

The clear color visualization of the room air temperature in the 3D model has supported the decision-making process and helped to convince the client of the proposed measures.

What would you have done differently with the graphic if you had more time/fee?

The integration of the optimization measures into the graphic would have helped to support the decision-making process. Furthermore, the cooling loads could have been integrated into the graphics. The information should be added as additional layers of information to maintain the simplicity of the graphic.

What is the impact of operable glazing fraction on thermal comfort and natural ventilation potential?

PROJECT INFORMATION

Graphic Name:  What is the impact of operable glazing fraction on thermal comfort and natural ventilation potential?

Submitted by: Carl Sterner

Firm Name: Sefaira

Other contributors or acknowledgements (optional) 

What tools did you use to create the graphic?

  • Sefaira

  • Adobe Photoshop

  • SketchUp

What kind of graphic is this? Scatter Plot

Primary Inputs: Building geometry (zoned) with glazing; location (weather file); envelope properties, internal conditions, and HVAC parameters.

Primary Outputs: Comfort: % occupied hours within setpoint range (dry bulb temperature). Free area: the ratio of operable window area to floor area for each zone, measured against a target of 5%.

GRAPHIC INFORMATION

What are we looking at?

The graphic is showing two pieces of data relevant for determining the optimal amount of operable glazing for natural ventilation. The first chart (on the left) shows the impact of increasing operable glazing on predicted thermal comfort (the percent of occupied hours with dry bulb temperatures within setpoints). Thermal comfort improves until approximately 75% of glazing is operable, and tops out at 72% of occupied hours being comfortable. The second graphic (on the right) shows the current design’s “free area” -- the ratio of operable window area to floor area for each zone. A free area of 5% is a typical target value for naturally ventilated buildings, and has been codified in standards such as BREEAM in the UK and Title 24 in California. This graphic shows that a number of the building’s zones fail to meet this prescriptive criteria as currently designed. Taken together, the graphics indicate that more operable glazing is needed in many of the zones in order to provide good natural ventilation.

How did you make the graphic?

  1. Modeled building geometry in SketchUp

  2. Uploaded the model to the Sefaira web application

  3. Set up the various simulations (envelope, internal conditions, and HVAC parameters)

  4. Ran a Response Curve for Operable Glazing %, looking at the impact on Thermal Comfort. Exported the resulting graphic.

  5. Ran a Free Area assessment, with a target of 5% free area. Exported the resulting graphic.

  6. Combined the two graphics in Photoshop

What specific investigation questions led to the production of this graphic?

  • Is there enough operable window area in each zone to provide good natural ventilation?

How does this graphic fit into the larger design investigations and what did you learn from producing the graphic?

This graphic was combined with other analyses related to the window area, related to daylighting and solar gain. The purpose of these combined investigations was to evaluate whether the glazing strategy and facade design was effective from energy, daylight, and natural ventilation perspectives. The initial glazing ratios were fairly conservative, and the analyses showed that the design would benefit from more glazing in many of the zones, for both natural ventilation and daylighting.

What was successful and/or unique about the graphic in how it communicates information?

The graphic summarizes and clearly presents fairly complex analysis, making the results actionable. It is easy to see how operable glazing affects comfort, and where the problem areas are in the existing design.

What would you have done differently with the graphic if you had more time/fee?

More clearly connected to two graphs, perhaps by finding a way to put them both in terms of absolute glazing area. The Response Curve is currently terms of % of glazing that is operable, while the Free Area chart is currently based on operable glazing area. This makes it difficult to clearly relate the two.

What is the impact of Electrochromic Glazing on thermal comfort and outdoor view vs LowE with manual shades?

PROJECT INFORMATION

Graphic Name: What is the impact of Electrochromic Glazing on thermal comfort and outdoor view vs LowE with manual shades?

Submitted by: Ranojoy Dutta

Firm Name: NA

Other contributors or acknowledgements (optional)

What tools did you use to create the graphic?

  • EnergyPlus

  • Grasshopper

  • Honeybee

  • Excel

What kind of graphic is this? Pie chart, Bar chart, Line plot

Primary Inputs: The inputs for the Predicted Mean Vote analysis are hourly values of surface temperatures, air temperature, radiant temperatures. They were generated by running an annual energy simulation for two glazing options.

Primary Outputs: Predicted Mean Vote; Manual Shade Usage Hours ; EC Tint State Hours

GRAPHIC INFORMATION

What are we looking at?

This is a winter thermal comfort analysis for an occupant sitting 1.2 m away from glazing on the south side of a commercial office. The data is recorded from 8 am to 6 pm daily, for the coldest week as per the EPW file fro Chicago, IL. This week represents the effect of intense solar radiation on the south along with the lowest average outdoor air temperature (OAT < -10 ºC).

Due to the low sun altitude (< 30º) in winter whenever there is a clear sunny day the occupants on the south side will experience severe discomfort from glare and overheating even though the OAT is well below 0 C. This condition exists for days 1 & 4 (Panel 5) with high incident radiation throughout the day. As a result, the Electrochromic(EC) glazing stays at Tint 4 (darkest) and the shades are also modeled as fully down. When glare is not a problem EC transitions back to a lighter tint state with higher Tvis and SHGC to allow more daylight as well as passive heating. This is evident for days 3 & 5, where there are only a couple of hours which require darker tints but as the incident radiation levels go down EC selects lighter tint states (Panel 3). On the other hand, once the manual blinds come down they stay down (Panel 4) regardless of improved outside conditions, blocking useful solar gain, reducing daylight and blocking outdoor views for 85% of the hours in that week. On the other hand using predictive controls EC only uses the darkest tint state ( Tint 4) for only 35% of hours (Panel 4), which will reduce daylight for those hours but still maintains full outdoor views.

The primary cause of winter discomfort near windows is inside glass surface temperature, which is dependent on the fenestration U-Value and the OAT. Hence, given the extreme low OAT for the chosen period the PMV is almost always below -0.5 for both glazing scenarios. EC offers comparable winter comfort with substantially more daylight, unobstructed views and greater scope for passive heating. The improvement in U-value from shading devices is minimal unless a relatively air-tight seal is made between the shade and window frame (e.g., with a track). Hence despite the shades being down for most of the time the PMV is only marginally better than VDG, but still mostly below -0.5.

How did you make the graphic?

A commercially available EC product was modeled with 4 tints using the Energy Management System (EMS) feature within Energy Plus v8.9 to replicate the exact manufacturer specified multi-criteria control algorithm . Outputs from this multi-state model were used for thermal comfort analysis using Honeybee. PMV results were then analyzed in Excel. Hourly values for EC Tint states and manual shade status (Up/down) was extracted from the energy plus models and add to the graphic in excel.

What specific investigation questions led to the production of this graphic?

  • This study was aimed at evaluating occupant comfort and access to outdoor views by increasing window wall ratio (WWR) with EC glazing to 55% for a commercial office in Chicago vs a 40% WWR with standard Low-E glazing with manual shades. The 55 % WWR for EC was determined by annual energy and peak HVAC analysis.

How does this graphic fit into the larger design investigations and what did you learn from producing the graphic?

This study found that the WWR for a mid-rise office could be increased by 25 - 50% with EC without any HVAC or energy penalty across three distinct climate zones. This translated to significantly higher daylight, greater viewing area and full glare control with year-round outdoor views vs LowE_Shd at 40% WWR. This specific graphic showed that while EC might have marginally more winter discomfort under very low outdoor temperatures it still provides unobstructed views and greater scope for passive heating and daylight in winter. The winter discomfort can be rectified by selecting a lower U-Value.

What was successful and/or unique about the graphic in how it communicates information?

This graphic shows the impact of manual shades staying down regardless of changing outdoor conditions, resulting in blocked view and daylight. The EC glazing however automatically tracks the outside solar conditions ( sun angles and intensity )to chose an appropriate tint state. The outdoor conditions chart show that despite subzero temperatures the incident solar radiation is still very high with a potential for discomfort from overheating and glare unless shades are fully down or EC is in its darkest state. However unlike manual shades EC never blocks outdoor views.

What would you have done differently with the graphic if you had more time/fee?

I would have liked to make this a web based graphic such that a user could adjust the date period from one week to one month or even a year. Also it would be nice to look at the other façade orientations and other cities. I had all the data but could not present it all due to lack of time.

What's the impact of facade design on thermal comfort?

PROJECT INFORMATION

Graphic Name: What's the impact of facade design on thermal comfort?

Submitted by: Andrew Corney           

Firm Name: Sefaira

What tools did you use to create the graphic? Sefaira

What kind of graphic is this? Floor Plan Heat Map

GRAPHIC INFORMATION

What are we looking at?

Provides a floor plan view of the building, coloured with information per zone describing whether they achieve a thermal comfort target.

The comfort target is shown in the criteria above. The user can quickly hone in on the zones that are failing one floor at a time.

By presenting the results in plan view, with the rooms shown, it presents results visually in a way that an audience familiar with the floor plate layout can process easily.

How did you make the graphic?

Sefaira makes these outputs automatically with any analysis run including thermal comfort.

What specific investigation questions led to the production of this graphic?

This graphic tries to help the designer understand “which zones are having the most trouble in my building” and then communicate that as needed to a wider team.

Traditionally consultants have to do this by:

  • Declaring for themselves what they expect the worst zone to be based on experience
  • Building thermal models of the zones that are declared as likely to be the worst

Relying on the trust between them on the design team to use that to steer design attention on those spaces.

This workflow is tedious and also in part risky, especially if the analyst is inexperienced and the reviewer is not privy to all the envelope details on a project.

The goal here is to help a designer hone in quickly on the spaces they should worry about first, while providing an easy way of proving that declaration to the rest of the design team.

How does this graphic fit into the larger design investigations and what did you learn from producing the graphic?

The graphic helps with facade design by identifying where thermal comfort goals are being missed. They should be incorporated into studies looking into peak loads, energy and daylight because all of these issues are affected by the envelope design.

The learning is that thermal comfort can be used as a design tool and that it can provide very helpful insight into how successfully a design is working.

What was successful and/or unique about the graphic in how it communicates information?

Thermal comfort analysis is typically time consuming and hard. It therefore requires a lot of preparation before analysis can be useful.

This graphic is helpful because it makes it really easy to see which spaces are struggling to meet the thermal comfort goals. It reduces the effort needed to hone in on the key spaces requiring attention and serves to prove visually the design team that those spaces are worse.

What would you have done differently with the graphic if you had more time/fee?

We ended up adding a gradient option to this graphic. The reason was so that people could identify which zones were just failing vs those that were the worst on the floor plate.

We’re interested in exploring how to convert this graphic into a comparative analysis, where a project has a series of design options and wants to compare PMV for the worst zone against those options and somehow communicate it on the floor plan.

What is the impact of shade on ASHRAE 55 thermal comfort acceptability limits?

PROJECT INFORMATION

Graphic Name: What is the impact of shade on hourly ASHRAE 55 thermal comfort acceptability limits? 

Submitted by:  Madeline Gradillas

Firm Name: Atelier Ten

Other contributors or acknowledgements (optional) An Vo - Atelier Ten, Kyosuke Hiyama - Meiji University

What tools did you use to create the graphic?

  • Design Builder
  • Excel
  • Adobe Illustrator
  • Adobe InDesign
  • Archsim

What kind of graphic is this? 12/24 Plot

Primary Inputs: outdoor climate/weather data, shade vs. sun

Primary Outputs: hourly temperature delta to achieve ASHRAE 55 80% acceptability limit (<20% PPD)

GRAPHIC INFORMATION

What are we looking at?

Examples of a chart plotting annual hourly values, where the horizontal shows each day of the year and vertical each hour of the day.

Each data point is plotted according to a conditional relationship with established standards and/or project specific design questions.  The light blue color represents hours that meet ASHRAE 55's 80% acceptability limits (<20% PPD), while the other colors in the legend show how many degrees Fahrenheit (in operative temperature) it would take to achieve the 80% acceptability limit threshold.  

Two sample uses of the hourly chart are shown here:

Example 1 (top image) - Operative Temperature, per ASHRAE 55 Adaptive Thermal Comfort Model 80% Acceptability Limits

Example 2 (bottom image) - Perceived Operative Temperature of a Body in Direct Sun, per ASHRAE 55 Adaptive Thermal Comfort Model 80% Acceptability Limits

How did you make the graphic?

Excel was used to post-process the data. Illustrator and InDesign were used to edit the original chart into a legible graphic.

What specific investigation questions led to the production of this graphic?

This graphic was first developed to be a flexible tool for post-analysis assessment, to understand the relationship between energy model/calculative outputs and project-specific questions such as:

-When does the value fall out of acceptability limits? What is the magnitude and frequency of these occurrences over a year?

-Do client or designer expectations of acceptability match those of the established standards’?

-Do the values show daily and/or seasonal trends?

How does this graphic fit into the larger design investigations and what did you learn from producing the graphic?

This is a useful as tool to establish baseline performance during conceptual design, and then as a comparison tool during design development.

Several plots can be easily viewed side by side to track the effect of design decisions on project performance.

Because data is plotted according to a series of conditional statements explicitly defined by the analyst, the resulting graphics' communicative success depends on the clarity of questions the analyst asks during its making.

What was successful and/or unique about the graphic in how it communicates information?

We continue to adapt this graphic at Atelier Ten to help ourselves and clients better understand increasingly complex questions and discover correlations between performance and design decisions, without having to re-run time-consuming models every time a design changes. Example 2 is one of the more recent plots that shows not only the relationship of operative temperature to ASHRAE adaptive comfort limits, but the "perceived" operative temperature an occupant experiences when in direct sun.

We found both graphics helpful when viewed side by side to communicate the importance of an extensive exterior shading system that was in danger of being VE'd out of a project.

What would you have done differently with the graphic if you had more time/fee?

Our current  Excel to Illustrator to InDesign workflow is clunky. Ideally this tool would auto-populate a legend and chart text that are easy to customize.