New updates to Washington State Energy Code bring sustainability to the forefront

Changes are coming to the Washington State Energy Code.

11/14/2016


Written to maintain Washington State's status as one of the nation's leaders in sustainable building design, several aggressive updates have been made to the state's 2015 code, including requirements for dedicated outdoor air systems and a series of sustainable design prerequisites project teams must choose from.

A new requirement for inclusion of a dedicated outdoor air system (DOAS) stands to change how engineers and architects alike approach design. Designers are now required to decouple the heating and cooling system from ventilation systems. According to the new code language, HVAC systems should now include "supply-air temperature controls that automatically reset the supply-air temperature in response to representative building loads, or to outdoor air temperatures." Because these systems have traditionally been linked, heating and cooling equipment have become major sources of wasted energy-pushing fans unnecessarily hard to maintain optimum comfort levels. The new approach will greatly reduce overcooling or overheating interior spaces and mitigate wasted fan energy.

The change will force manufacturers to innovate new solutions, since packaged rooftop units will no longer be viable. There is a side benefit to the overall design, however. While HVAC systems will require more equipment, the overall size of that equipment could potentially decrease, creating the opportunity to increase ceiling heights.

Also new to the code is a selection of energy-efficient design strategies, of which design teams must choose a minimum of two to be code-compliant. Of the available options, a focus seems to be on reduction of both lighting loads and fossil fuel usage. The code updates focus on enhanced lighting controls, a 25% reduction in lighting power, onsite renewable energy, and high-efficiency domestic hot-water sources for 60% of the load (e.g., waste-heat recovery or solar hot-water systems). These features are designed to imbue future projects with greater efficiencies and sustainable designs.

These changes will add costs and additional design considerations. It's recommended that project teams take advantage of the interim year by providing alternative designs featuring the DOAS to allow developers and architects to adjust to the new pricing and timelines. This will help spread awareness of the new code and avoid surprise costs once they truly go into effect.

-Max Wilson, PE, LEED AP, BEMP, is senior energy analyst at Glumac, a CFE Media content partner. This article originally appeared on www.glumac.com



Anonymous , 11/16/16 11:17 AM:

Has there been a study by the US Department of Energy to show DOAS to be more energy efficient that present HVAC equipment?
John , IL, United States, 11/16/16 02:14 PM:

As I understood, the code doesn’t prevent specifying engineers from designing an all air system as long as they apply DOAS in parallel arrangement (the all air system can be VAV or CV, chilled water based or DX). The statement in the article (see below), is incorrect, the package Rooftop unit can be single zone (PSZ) unit handling the space cooling and the heating loads and the OA can be delivered to the zone by a parallel DOAS system (this system will comply with the prescriptive approach) . And as an extra benefit, the PSZ can provide free cooling with the economizer.(WA is good CZ for air side economizer). It seems like there is a confusion with the new code.

Quote from article: "The change will force manufacturers to innovate new solutions, since packaged rooftop units will no longer be viable. There is a side benefit to the overall design, however. While HVAC systems will require more equipment, the overall size of that equipment could potentially decrease, creating the opportunity to increase ceiling heights."
John , IL, United States, 11/22/16 09:34 AM:

The paper misses several important issues and may confuse / mislead the readers. Below are our comments:
1. The DOAS requirement ( section C 403.6) prescriptively ( not mandatory) required only for the following applications:
- Office
- Retail
- Education
- Libraries
- Fire stations
DOAS is not required for other applications.
2. The 2015 WA State Energy Code allows the use of High Efficiency Variable Air Volume (VAV) ( section C 403.7) as an alternative to the DOAS system described in section C 403.6.Under this section DOAS system for High Efficiency Variable Air Volume system is not required.
3. The designer can apply the Total Building Performance Path ( section C 407) where he or she can specify any HVAC system without a DOAS as long the proposed design meets the Performance Based Compliance section( section C 407.3).
4. The new 2015 WA State Energy Code , under certain circumstances ,( and with the approval of the code official) exempts the DOAS provision if found to be impractical ( section C 403.6.3)
5. The 2015 WA State Energy Code doesn’t restrict the designer to apply an All - Air systems such as Multi Zone VAV , SZ – VAV , and systems such as DX – PVAV and DX – PSZ in conjunction with a DOAS , 100 % OA independent system operating in parallel arrangement . With this arrangement OA for ventilation is delivered to each zone Independently of the air delivered from the air handing units (used for heating and cooling). This arrangement decouples the zone ventilation from the thermal load treatment (cooling and heating). An important advantage of this system is the ability of the all air system to provide free cooling by utilizing the air side economizer which can be cost effective in WA climates zones 4C and 5B.
6. The 2015 WA State Energy Code in the performance approach (Total Building Performance, section C 407) , for certain cases suggests the use of Packaged Rooftop Heat Pump and Packaged Rooftop Air Conditioner ( systems 9 and 11 respectively) in table C407.5.1(4) along with a DOAS operating in parallel to the cooling and heating system as suggested by note “k” in the table.) , these two (2) systems are the “ Standard Reference Design” ( the equivalent of the Budget Building Design of the ASHRAE 90.1 ECB ) . Although, these systems are used only for modeling, they are legitimate and valid systems The statement “since packaged rooftop units will no longer be viable.” In the paper is inaccurate and misleading.
There is confusion in the paper with regard to the following:” A new requirement for inclusion of a dedicated outdoor air system (DOAS) stands to change how engineers and architects alike approach design. Designers are now required to decouple the heating and cooling system from ventilation systems. According to the new code language, HVAC systems should now include "supply-air temperature controls that automatically reset the supply-air temperature in response to representative building loads, or to outdoor air temperatures." This statement can confuse the reader, as indicated previously the DOAS requirement is in section 403.6. The requirement to reset the supply air temperature is in section C 403.4.4.4 which refers to VAV systems (under section C 403.4.4). For cases where a the design is based on VRF, WSHP or Fan Coils in conjunction with 100 % OA DOAS unit, ( typically) Supply Air temperature reset is not common/applicable . However, the supply air temperature reset is common practice with VAV systems and can be found in other energy standards such as ASHRAE 90.1. It should be noted, that a VAV system in parallel to a 100 % OA DOAS systems, can apply this feature. It was appropriate to explain these issues more clearly to avoid confusion.
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