Education Series part three of three
HIGH PERFORMANCE EDUCATION
1
From Net Zero to Net Positive & Beyond. written by: Michael Flemming pe, leed ap, bd+c, cxa, cem associate principal, commissioning agent 2
Steve Gross pe associate principal, sr. energy analyst
Applied Building Sciences and Commissioning Services delivering high performance schools
e
As we’ve highlighted in the previous sections of this educational series, the high-performance K-12 market presents unique challenges that requires a sensible balance of efficiency, low maintenance, and cost effectiveness while providing students and staff with a modern, healthy, and comfortable space to thrive. In this portion of the series, we are going to highlight why, particularly for K-12 projects, it’s so important to think about building performance holistically. Starting from the very concept of a project, all the way through to the start of the school year and beyond, Interface Engineering’s Building Performance Team provides valuable insight and extensive analytical capabilities to guide a team to delivering truly high-performance spaces.
Interface Engineering design team reviewing virtual reality walkthrough of a new K12 performing arts building.
3
Our Building Performance Team combines two critical components of a high-performance design team that are traditionally separate trades: Building Science and Commissioning. Through our experience on over 2,000 K-12 projects, we have found that combining the expertise of both teams throughout the length of a project can have a dramatic impact on the success of a project, as experienced by all project stakeholders. We know that each stakeholder group will have a different view of what success means for their project. Our Building Performance Team can be an effective tool to help balance the competing interests. Our team’s goal is to leave the following stakeholders satisfied: » Finance Team » Principals/Teachers » Parents » Students » Facilities Personnel
Interface Engineering design team meeting
4
5
DESIGN WITH ANALYSIS
Our Building Performance Team uses the world’s most advanced building simulation tools to investigate all facets of the built environment.
We leverage these tools to guide the design process, serving as an internal consultant to our MEP design teams, as well as to our external clients. We work with architects and interior designers to optimize construction materials, glazing placement, and furniture layouts to minimize energy consumption and maximize passive design measures such as daylighting and natural ventilation. Appropriate MEP system selection is critical for K-12 projects because operating resources are finite. Our Building Performance team aids in this process by proposing and modeling multiple alternatives for each project and presents the pros and cons of each through a combination of energy and financial analyses.
In the example at right in Figure 1 and Figure 2 for the Ocean View Elementary School in the Albany Unified School District (CA), the annual energy and life cycle cost performance of two mechanical system options are compared against a Title 24-2016
6
baseline building. In this case, we are comparing single-zone heat pumps (SZHPs) to Variable Refrigerant Flow (VRF) systems. The results show the VRF system to have the lowest annual energy performance, with an EUI of 23.8 kBtu/ft2-yr. However, when we look at the 25-year life cycle cost comparison, we see that the SZHP has a much lower total cost. This means that the energy savings of the VRF system was not significant enough to overcome the first cost savings of the SZHP option. In this case, our final recommendation for the project was to proceed with the SZHP design, as it showed the lowest cost of ownership and still achieves a 23% reduction over the T24 baseline and will allow Net Zero Ready capabilities. Further, this system is familiar to the district’s maintenance staff and was approved.
40.00
33.63
35.00
25.8
23.8
4.4
10.93
EUI
30.00
SHW (elec)
2.2
1.6 2.1
Fans
25.00
20.00
1.9 2.0
15.00
Heat Rejection Pumps 10.16
10.2
10.2
5.83
5.5
5.5
BASELINE-TITLE 24
SINGLE ZONE HEAT PUMPS
VRF
Cooling
EUI (KBTU/SQFT)
1.96 2.57
10.00
Heating (elec) Heating (gas)
5.00
Plugs Lighting
0
Figure 1 | MEP System EnergyComparison Comparison Figure 1 MEP System Energy
Cumulative Discounted Cash Flow $1,800 $1,600 $1,400
THOUSANDS ($)
$1,200 $1,000 $800 $600 $400 $200 $0 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
YEAR HVAC Scenario 1: SZHPs and PRTUs
HVAC Scenario 2: VRFs
Figure 2 | Life Cycle Cost Comparison of MEP Options 7
LOW MAINTENANCE AND OPERATIONAL SIMPLICITY
An essential focus of our K-12 work as a combined Building Science and Commissioning group is to analyze the maintenance projections for various design options. This involves engaging directly with maintenance personnel (both managers and technicians) to understand their unique capabilities and available staffing. This feedback is used to generate detailed life cycle cost projections as well as prioritize MEP system selection. Operational simplicity is also paramount for K-12 schools. Depending on the level of experience for the maintenance staff, systems similar to the one on the upper left would be better than the system on the right. 8
PROPER COMMISSIONING AND CONTROL
The challenges of building a highperformance K-12 school are not only limited to the design portion of the project. Some of the biggest challenges can come from making the project work and ensuring that the design is implemented correctly in the field. Interface Engineering’s Building Performance team has participated in countless projects and from our experience, K-12 projects include many difficult implementation challenges that aren’t faced by a typical building: » Long periods of the summer with minimal occupancy. » Flexible spaces that have multiple different uses throughout the school year.
» Lockdown systems » Indoor Air Quality » Maintenance staff with limited
Some of the biggest challenges can come from making the project work and ensuring that the design is implemented correctly in the field.
experience in complex systems. During commissioning, the entire building must be tested under the different conditions that the project will encounter throughout the school year. It isn’t sufficient to test each system individually when in many schools, each
integration between shades, lighting and mechanical controls systems should not be overlooked. Because ultimately nothing is more important than the safety of the children!
space will interact with the others in a
Indoor air quality (IAQ) and thermal
different way.
comfort are important factors that
A new challenge being faced by many
can greatly impact a student’s ability
schools is the integration of mechanical
to learn in the classroom. We feel it’s
and lighting systems into the building
incredibly important to prioritize design
lockdown mode. Knowing that the
elements and commissioning processes
system will be able to react correctly
that ensure clean air and a comfortable
in case of emergency is of the utmost
environment are available to all students
importance and thorough testing of the
and staff. 9
Here are a few strategies that we have extensive experience implementing: » Ceiling fan integrated cooling (Further Reading) » Displacement Ventilation » Automated Natural Ventilation » Radiant Heating and Cooling » No Combustion Heating Systems Finally, ensuring that the Facilities Staff understand the building is of upmost importance for the long-lasting 10
operation of the project. Ensure training is implemented and is effective and encouraging Facilities Staff to be involved in the commissioning and testing helps to educate the team and helps to provide ongoing savings. Additionally, ensuring that the controls graphics match the maintenance personnel make it more likely that the building will be operated correctly, some people love data, while others love visuals, every little thing to make it easier to operate will make for a happier operator.
Through our extensive commissioning experience of K12 schools we have faced many difficult challenges. Below are some of the common issues we’ve faced and how we’ve worked to resolve them: 1 | Spikes in CO2 correlate to massive temperature changes. Increase ventilation on cold/hot days can cause massive temperature changes and cause the spaces to overcompensate. Knowing that these spikes will occur means that the controls system must be able to predict and compensate appropriately. The Interface Building Performance team has worked closely with controls and mechanical contractors to ensure that PID loops are tuned accurately for the project and the space and to ensure that both IAQ and occupant comfort are met throughout the school day. On a recent project the difference between reacting to CO2 when it was 800ppm instead of 900ppm allowed for a slowed response and meant that temperature swings in the space were slowed from 0.15-degree/minute to 0.02-degree/minute making a big difference on occupant comfort. Michael Flemming and Steve Gross
11
2 | Thermostats out of Calibration or poorly placed. With simple mechanical systems the most important piece in controls is the thermostat. However, when a thermostat is out of calibration or in the wrong place from the beginning of the project, the system will forever have issues achieving optimal comfort. On recent site visits the Interface team observed thermostats in Hawaii that where responsible for dehumidification reading 100% relative humidity before the building was occupied. With most thermostats being factory calibrated, not checking these simple devices can make thermal comfort and energy savings impossible to achieve. The same issue occurs when thermostats are placed on exterior walls or behind doors that are likely to be open. The location is especially important when CO2 control is included and therefore placement is extremely important. 3 | Inconsistent occupancy schedules. Utilizing standard occupancy schedules can result in spaces not being adequately served when large gatherings occur or can lead to spaces being over-conditioned when occupancy is low. To address this issue, occupancy sensors and CO2 sensors should be utilized as much as necessary to determine the load in the space so that conditions can be met and energy savings can be achieved when occupancy is low. Commissioning in the Field
12
13
i n t e r fac e e n g i n e e r i n g
14