Rendering of Norwood Park Elementary School

Encompass tackles the complex renovation and expansion of an 86 year-old school complex. They are using Sefaira to investigate the impact of design decisions on overall energy and daylight building performance.

Project Stats

Project type: Renovation and expansion of an existing school complex

Location: Nebraska

Building type: Education – Elementary School

Floor area / stories / occupancy: 7,100sf cafeteria & food service / 1 story + 3,850sf Mechanical Mezzanine + 15,250sf New Roof

Budget: Withheld

Project stage: Design Development

Introduction

Norwood Park Elementary School was built in 1926, with additions made in 1957, 1963 and 2010. Due to the increased number of elementary school students in the area, the school requires an additional food service and cafeteria area, and additional space for mechanical systems on a mezzanine level.

Retrofit & New Build Plan

The Design Challenge

Encompass Architecture needed to improve performance for an existing collection of buildings while seamlessly integrating high-performing new additions.

To meet this challenge, Encompass used Sefaira’s Revit Plug-In and the Sefaira Web App to understand the existing building’s energy and daylight performance, analysing strategies to achieve well-lit, efficient spaces.

Approach

Encompass started by creating a model of the existing building, setting it up with an ASHRAE 90.1 2013 baseline. Next, they went on to optimise the:

  1. glazing ratio on an existing facade
  2. glazing ratio and shading for the new cafeteria
  3. envelope for the new cafeteria
  4. roof for the new mezzanine roof

Here’s how they did it.

Optimising the Glazing Ratio on an Existing Facade:

Ten windows on the existing west facade had been filled in at some point in the school’s history. The design team wanted to find out the impact on daylight levels and glare (sDA & ASE), if these were opened up once more. Re-establishing the windows on the west facade increased the glazing ratio from 19% to 30%.

Table showing results for glazing optimisation

Analysis indicated that this increased glare on the 1st floor plane by 20%.

The team used parametric analysis in Sefaira Architecture’s web app to determine the ideal glazing ratio for balancing energy consumption, cooling and heating loads. Increasing the glazing ratio had a negligible effect on all three factors (+/-%), making it a feasible design option.

Optimising the New Cafeteria Glazing Ratio (south & east facades):

Next, the team compared three glazing ratios for the new cafeteria — a 35% glazing ratio baseline,  a 50% glazing option and then to a 50% glazing option with a horizontal projection.

Table showing results for glazing ratio tests

The daylight visualisation from Sefaira clearly shows increased daylight levels deeper in the floor plate in options 2 and 3. Without shading, as in option 2, a lot more of this natural light is glare.

Cafeteria Analysis showing improvements

The shading on option 3 was then parametrically analysed to determine the ideal length for balancing heating and cooling loads.

Cafeteria Analysis 4 Optimising wall specification

Starting with the minimum required code of ASHRAE 90.1 2013, the team compared these results to various other envelopes (R5 – R30), including the practice’s standard assembly. They discovered that specifying their standard assembly leads to a 5% decrease in Annual Heating over the baseline and specifying the R20 and R30 values offered an 8% and 11% improvement respectively.

Comparative Wall R Values

Optimising the roof specification

The baseline roof specification of R-30.87 for the cafeteria was already quite high performing – an improvement to R-40 would lead to a 5% reduction in Annual Heating Loads.

Comparative Roof  R Value

Choosing this higher roof specification (R-40) would also impose an added capital cost of $5900.

Cost Analysis Roof R-Value

Result

The team decided to leave the existing building in its existing form – all ten west facing windows would remain filled in. The wall served as vital surface area for teaching and this option meant they could avoid any additional glare within the teaching space.

For the new cafeteria, they selected the higher glazing ratio of 50% with a horizontal projection for shading. Sefaira results showed that this option balances daylight and energy best, increasing sDA by 30% and offering a light new cafeteria for students and school staff without unwanted glare.

A better performing wall specification with an R value of 20 was selected over the code minimum of R11.12, resulting in an 8% reduction in Annual Heating Loads. Specifying an R-value higher than this was not a good investment because it did not reduce operating costs by a significant amount, despite being more expensive to buy.

For the mezzanine roof, specifying a buildup of R-40 yielded a 5% reduction in Annual Heating Loads. This was not a feasible option when reviewed against the added cost (an additional $0.38 per square foot. 15,500sf in total = $5,900). As such, the reasonable choice was to specify the high performing code baseline value.

Overall, the design team analysed numerous scenarios and verified results through team reviews and collaboration with engineers. Sefaira results were crucial for presenting various design options and helped illustrate the impact of each decision on building performance and cost to the client.

“Encompass Architects was founded on the commitment to sustainable design. Our challenge has been a lack of means to test and measure the value and impact of sustainable strategies, especially in the initial stages of design. Sefaira allows us to evaluate options early in the design process and quickly arrive at value-driven solutions which minimise initial costs and maximise long term building performance. Most importantly, the information allows our clients to make better and more informed decisions regarding their project.” Todd Hesson, AIA Vice President Encompass Architects.

About Encompass Architects

Encompass Architecture

Encompass Architects, based in Nebraska, is a national practice which prides itself in delivering highly contextual projects by working closely with clients to achieve their aims. They utilise a research based design process to learn and understand the brief, achieve sustainable design goals and implement project strategies. Performance-based design is a fundamental part of the practice policy and early stage analysis allows Encompass Architects to better meet client needs.