How to win LEED certification points and apply ASHRAE in the design process with FenestraPro?

Why LEED certification?

Sustainable construction and high-performance architecture is ever more popular. Just few days ago the reputable architecture studio Foster + Partners announced that from 2030 they will design only carbon neutral buildings. And a recent research from USGBC shows that half of the respondents expect to build more than 60 percent of their projects as green buildings by 2021 – all of this driven mostly by client requirements and environmental regulations.

Apparently, this trend leads to increase of popularity of the LEED certification – probably the most popular sustainability symbol in design and construction in the world. As of 2018, only in USA there are 67 208 certified LEED projects. This is compared to just 41 in year 2000.

So, let us talk about how to ensure easier consideration of LEED requirements in the design process of a building. While there are four levels of LEED certification, they all use a certain number of credits according to different categories. In this article we will demonstrate how to manage passive considerations of energy efficiency and more specifically:

  • Building envelope, opaque: roofs, walls, floors, slabs, doors, and continuous air barriers (1 point)
  • Building envelope, glazing: vertical fenestration (1 point)
  • Interior lighting, including daylighting and interior finishes (1 point)

“LEED, or Leadership in Energy and Environmental Design, is the most widely used green building rating system in the world. Available for virtually all building, community and home project types, LEED provides a framework to create healthy, highly efficient and cost-saving green buildings. LEED certification is a globally recognized symbol of sustainability achievement.”

To manage properly for these considerations, the design team should use the ASHRAE 50% Advanced Energy Design Guide (AEDG) and the appropriate climate zone. For projects outside the U.S., consult ASHRAE/ASHRAE/IESNA Standard 90.1–2010, Appendixes B and D, to determine the appropriate climate zone. ASHRAE has very detailed and extensive prescriptions, including recommendations how to manage the design process in order to achieve the high-performance design goals.

It is important to have couple of things in mind before going into the details of energy efficiency management. 50% AEDG series recommends for achieving 50% site energy savings beyond Standard 90.1-2004 through integrated design, a holistic approach to design that focuses on optimizing the synergy between building systems, as opposed to independent design at the system level.

The 50% AEDG series also offers a performance-based path to achieving the efficiency goal. As savings targets become more aggressive, it becomes less and less practical to recommend a one-size-fits-all approach to design. Many of the 50% AEDGs present whole-building absolute energy targets that reflect recommended strategies and encourage design teams to develop innovative, project-specific solutions that can leverage the principles of integrated design to maximize the cost effectiveness of high-performance design.

Therefore, we must understand that the 30% and 50% AEDG do not give the exact solutions for each particular project but allow for several different approaches which are both not exclusive and complete. There are could be other approaches which would allow for achieving the goals.

So, let us go through the design process and see how FenestraPro facilitates the high-performance facade design for LEED.

What is the Advanced Energy Design Guide?

Here is a short view  of the AEDG process and the performance parameters that can be managed by FenestraPro applications.

Design Project Kick-off

The project kick-off meeting is the most important meeting of the entire project with regards to establishing the Owner’s Project Requirements (OPR). This allows the owner and stakeholders to define what a successful project means for them. The requirements can cover construction costs, longevity, operating costs, specific characteristics, required spaces, functional aspects, specific maintenance or system preferences, frequency of use, aspirational goals, and any other critical issues.

Functional requirements would typically include the indoor environmental quality goals, thermal comfort for occupants, acoustic performance of the space, or lighting levels to support the necessary work tasks. It is strongly recommended that the OPR arising from the commissioning process includes the following information: targeted energy labels and/or energy ratings like Building eQ (ASHRAE 2011), Leadership in Energy and Environmental Design (LEED) (USGBC 2011), any constraints imposed by the site, code, or planning agreements with the city, pre-existing standards (if any), etc.

Concept Design

Concept design usually consists of series of brainstorming sessions that allow the project team to review the OPR in the context of the site for any opportunities and risks. A key part of this stage is to investigate the site and look for shading or wind-shadows from adjacent buildings. Additional considerations at this stage are availability of natural resources like sun, hardscaping or landscaping potential to reduce heat island effect or provide natural shading.

As next step in this stage, it is important to analyse options on the façade orientation in the context of the site and think about the energy solutions, skin treatment or shading, also for occupants’ comfort. Some detailed considerations are:

  • daylighting potential versus glare versus solar heat gain, lazing types, shading devices, and fenestration size, perimeter occupant comfort
  • projected heat loss/heat gain and impact on annual HVAC energy use
  • daylight harvesting and impact on potential energy savings
  • landscaping potential for natural shading

Schematic Design

Within the schematic design phase the project team further develops the ideas, still feasible given the OPR and the constraints on site. At this phase, the architectural team usually begins to identify the various occupancy options like leaving the centre of the building for frequently unoccupied zones (conference rooms, copier rooms, storage areas, stairs, and restrooms) or high-heat-load areas (server rooms).

Very quickly this leads to the identification of façade locations where glazing would be desired to enhance the indoor environment for the occupants. At this point, the prediction of solar path (specifically, profile angle) is recommended to assess the exposure of intended glazing locations and the resulting penetration of solar rays into the occupied perimeter zone.

And in this already early stage becomes extremely important for the design team to do back-check on glazing areas and thermal performance against the ASHRAE/IES Standard 90.1 prescriptive requirements (ASHRAE 2010) or the recommendations for the relevant climate zone. This stage is critical because the team must avoid designs with sub-optimal glazing, either too heavily glazed or glazed below optimal performance levels.

In addition, at this stage an in-depth analysis is required for the quantity and “frequency of occurrence” of natural resources like daylighting.

And last, in the schematic design phase the design team identifies the energy conservation measures (ECMs). As noted earlier, there are possible trade-offs between different measures, because they could affect each other. Looking at the passive performance parameters of the building, at this stage it is important to consider:

  • Selection of a façade type and orientation and each face’s relative proportion and performance of glazing and opaque wall insulation
  • Selection of glazing visible transmittance (VT) versus solar heat gain coefficient to allow daylighting without overheating

Design Development 

At the design development phase, we apply the final ECM set onto the concrete architectural scheme. Now we are looking at the building envelope and related regulations. At this point the investment value becomes clearer and costs are becoming a factor.

But if an ECM is removed or changed, the unintended consequences of this decision must be explored and analysed; e.g., lowering the glazing VLT to reduce solar heat gain may eliminate daylighting as an ECM, which will require investigation of additional ECMs to meet the stated energy-saving goals.

Construction Documents (CDs)

The construction documents (CDs) phase is the final detailing of all systems, inclusive of sustainability features and ECMs.

How to use FenestraPro with the 50% AEDG design process?

FenestraPro family of BIM software brings value when used in all stages of the design process. FenestraPro greatly facilitated the AEDG design process – not only it allows for application of the performance parameters, but it also makes the process easier, less cumbersome, more effective and efficient for the architectural studio.

Let’s look at some of the concrete applications of FenestraPro when designing for high-performance building according to ASHRAE.

Concept design

During the concept design stage FenestraPro can give insight into critical building parameters like orientation and geometry according to the site specifics and natural resources like sun. FenestraPro allows for real time management of following parameters:

1. Site location and orientation

Based on geolocation and orientation of the building, FenestraPro utilises Meteonorm climate data to provide insights into the availability of natural resources like sun and to provide insight into the solar heat load on the surface of each façade.

2. Site and surrounding buildings

FenestraPro considers surrounding buildings and can help conceptual design with taking into account shading and the site environment.

3. Early stage massing and detailed models

FenestraPro analyses and interprets early conceptual design in relation to the building shape, size and volume and highlights their implications on its performance.

4. Optimal distribution of glazing

FenestraPro will give the architect guidance and design parameters on how best to distribute glazing around the building façade for maximum solar heat gain.

5. Daylighting analysis

Design daylight factors are provided to demonstrate the implications with regard to its performance on the daylighting levels, thereby reducing the requirements for artificial lighting.

Schematic design

In the schematic stage of the design process, FenestraPro gets even more powerful. The designers can apply FenestraPro tools for:

1. FenestraPro understands passive solar heat gain and natural daylighting considering glazing performance characteristics. It takes into account the solar path in the occupied perimeter zone and alerts for glaring. Then, FenestraPro allows for correction of the glazing design and management of solar shading options.

2. FenestraPro allows for setting of the required prescriptive regulatory requirements for thermal performance of the façade, which can be deployed in the design model.

3. Understand key performance characteristics of the building’s façade including thermal performance, surface solar loads, shading, internal heat gain and natural daylight.

And FenestraPro allows for following ECM management processes:

1.  Use FenestraPro to establish elemental and thermal performance values based on code to drive the optimal glass to wall ratio considering the buildings geometry.

2. Glazing specification tool – FenestraPro uses alternative glazing specifications to demonstrate the impact of the different glazing systems on the building’s performance.

3. Elemental and thermal performance: based on elemental thermal performance values and considering overall thermal performance of the building, the design team can establish the optimal performance levels.

4. Manage passive solar heat gain versus natural daylighting considering glazing performance characteristics.

Design development

Like discussed, at this stage ECMs are deployed, but then changes are possible.

The powerful functionality of FenestraPro allows for both applications of ECMs into the model with immediate visibility of their effect and powerful flexibility to change ECM parameters in order to accommodate other design goals.  Furthermore, at every iteration and stage, FenestraPro allows for powerful and rich reporting which can be used for communications with other project stakeholders and analysis.

Here is some of the FenestraPro functionalities, available at this stage:

1. Use FenestraPro to generate windows and curtain wall systems based on performance, specification and the design intent.

2. Select the most appropriate glazing type from an extensive database of glazing solutions to meet the performance criteria.

3. Optimize shading design: the designers can apply appropriate shading or fritting to ensure occupant comfort and prevent overheating.

4. Easy management and review of the changes in the building performance, coming from ECM downgrade.

5. Understand passive solar heat gain and natural daylighting considering glazing configurations and performance characteristics.

6. Detailed façade component selection and specification including performance characteristics.

7. Manage Understand key performance characteristics of the building’s façade including thermal performance, surface solar loads, shading, internal heat gain and natural daylight.

8. Use FenestraPro to generate detailed and customized reports and charts to demonstrate code compliance and performance considerations.

Use FenestraPro to extract and document detailed data on façade components and custom panels, including specifications, quantities, compliance and performance data.

Construction documents

FenestraPro can extract, create reports and share document detailed data on façade components and custom panels, including specifications, quantities, compliance and performance data.

At every stage of the design process, members of the team can rely on powerful and flexible HTML reporting and analytics for better decision making.

Project team can use FenestraPro to extract and document detailed data on façade components and custom panels, including specifications, quantities, compliance and performance data.

In conclusion, LEED and similar sustainability certification systems will become more and more important for the AEC industry and architects and designers could greatly simplify the building design process and link building’s aesthetics with the required performance using BIM technologies like FenestraPro.

LEED certification – final words

In conclusion, LEED and similar sustainability certification systems will become more and more important for the AEC industry and architects and designers could greatly simplify the building design process and link building’s aesthetics with the required performance using BIM technologies like FenestraPro.

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How to win LEED certification points and apply ASHRAE recommendations in the design process with FenestraPro

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