OpenBuildingControl: Digitizing the control delivery from building energy modeling to specification, implementation and formal verification

Michael Wetter,Paul Ehrlich,Antoine Gautier,Milica Grahovac,Philip Haves,Jianjun Hu,Anand Prakash,Dave Robin,Kun Zhang

doi:10.1016/j.energy.2021.121501

Michael Wetter, Paul Ehrlich + Show 7 more

Open Access

https://doi.org/10.1016/j.energy.2021.121501

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Abstract

The current process for specifying, installing and commissioning building control sequences is largely manual and based on ambiguous natural language specifications. It lacks a formal end-to-end quality control and it has been shown not to deliver high performance sequences at scale. While high-performance HVAC control sequences enable significant reductions in energy consumption, errors in implementing the control logic are common even for less advanced sequences. To improve this situation, we present a digitized building control delivery workflow with formal end-to-end verification, a Control Description Language for the digital specification of building control sequences within this workflow, and software tools that enable digitization of this process. Using the process and tools introduced here, mechanical designers can customize, test and improve these sequences within annual energy simulation, store them in a library for use in other projects, and export them for bidding. Control providers can implement the sequences on existing control product lines through code generation. Commissioning providers can formally verify whether as-installed sequences conform to the digital design specification that was exported by the mechanical designer. Moreover, control product development teams can use the reference implementations of these libraries within their product testing to ensure that their products reproduce the behavior of the reference implementations. This paper presents this process, the language and the supporting software, together with examples of all of the above steps. The presented work has given rise to a new proposed standard, ASHRAE 231P, that will allow digitizing the building control delivery process through the standardization of a control-vendor independent format for exchanging control logic that we pioneered through the here presented work.

Highlights

High performance building control sequences have been shown to significantly reduce energy consumption, with savings in the range of 23 %e30 % being common for most building types [11]
This section describes the Control Description Language (CDL) that we developed to support the OpenBuildingControl workflow described in this paper
This is the first implementation of a set of modular, but interdependent, computing tools that pave the path towards digitization of the controls development, specification, delivery and verification, under the major technical constraint of reusing existing building control product lines

Summary

Introduction

High performance building control sequences have been shown to significantly reduce energy consumption, with savings in the range of 23 %e30 % being common for most building types [11]. This requires control sequences to be properly designed and implemented. This study estimates the correction of control related problems to account for more than 75 % of the potential energy savings obtained in commissioning [9].

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