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CHAPTER 24

MUSEUMS, GALLERIES, ARCHIVES,

AND LIBRARIES

TERMINOLOGY ...................................................................... 24.1

KEY CONSIDERATIONS ........................................................ 24.2

CONTEXT AND PREDESIGN ................................................ 24.3

OVERVIEW OF RISKS ............................................................ 24.7

ENVIRONMENTAL EFFECTS ON COLLECTIONS.............. 24.7

DESIGN PARAMETERS FOR PERFORMANCE

TARGET SPECIFICATIONS ............................................. 24.19

24.

ed to Laszlo Horsik (lh CONTROLS DESIGN............................................................. 24.29

CONTROL EQUIPMENT ...................................................... 24.33

SYSTEM DESIGN AND SELECTION ................................... 24.34

CONSTRUCTION .................................................................. 24.42 COMMISSIONING ................................................................ 24.42

TRAINING AND DOCUMENTATION .................................. 24.42

OPTIMIZATION .................................................................... 24.43 HIS chapter presents best practices and advice on planning, Tdesigning, and implementing environmental strategies for long-term preservation of cultural heritage that also support access in an economically and environmentally responsible way. It aims to sup-port a holistic approach, taking into consideration the types of col-lections, buildings, and environmental control systems that can sustain appropriate conditions for specific collections with their own climate histories. It acknowledges that any strategy will have to be an integral part of heritage preservation as a whole. The chapter is applicable to museums, galleries, nonresidential historic buildings, reference libraries, and archives, as well as to both new and existing structures. It is not designed for buildings with public access that only hold collections not intended for preservation, such as school libraries.

This chapter is primarily directed at HVAC engineers and facility managers involved with indoor climate control projects in cultural heritage institutions, including new construction and extensions, renovations and upgrades of existing systems, and the adjustment of climate control strategies towards sustainability. Because this chapter has been widely used by allied professionals in a much broader context, it informs all stakeholders involved in the decision-making process on designing and implementing environmental strat-egies for cultural heritage collections. These include, but are not lim-ited to, engineers, architects, collection owners, cultural heritage administrators, collection managers, conservators, conservation sci-entists, curators and registrars.

The information in this chapter focuses on mechanical and, to a limited extent, nonmechanical approaches to the control of tempera-ture, relative humidity, and indoor air quality. Tables and graphs are used to provide clear and easy access to specific information, but the underlying text is necessary to understand the full context.

Other relevant ASHRAE resources include the following.

• ASHRAE’s Epidemic Task Force (ETF) (www.ashrae.org /technical-resources/resources). Established in March 2020, the ETF has developed an array of guidance documents on engineer-ing improvements to reduce the risk of infection in the built envi-ronment. One-page overviews of guidance for industrial settings, safe vaccine transportation, reducing exposure to airborne aero-sols, and various applications can be found at www.ashrae.org /technical-resources/covid-19-one-page-guidance-documents.

• ASHRAE Task Force for Building Decarbonization (TFBD).

The ASHRAE position statement on reducing carbon in buildings is available at www.ashrae.org/about/position-documents. Research

The preparation of this chapter is assigned to TC 9.8, Large Building Air- Conditioning Applications.

is ongoing to develop additional guidance, which is anticipated to begin release in 2023.

• Operational excellence. To help ensure that building HVAC sys-tems are designed and installed in ways that achieve excellent operation throughout the building’s life, an ASHRAE Presidential Elect Advisory Committee led by ASHRAE President Darryl Boyce developed and released Designing for Operational Excel-lence—Intentional Design for Effective Operation and Mainte-nance (ASHRAE 2022).

1. TERMINOLOGY

The terminology used in this chapter derives from the profes-sional conservation field and, except where noted, is taken from the website of the American Institute for Conservation of Historic and Artistic Works (AIC 2018).

Cultural property includes objects, collections, specimens, structures, or sites that have artistic, historic, scientific, religious, or social significance.

Tangible heritage includes buildings, historic places, and mon-uments, as well as objects and collections significant to the archae-ology, architecture, science, or technology of a specific culture.

Intangible heritage, according to the United Nations Educa-tional, Scientific and Cultural Organization (UNESCO), includes traditions or living expressions inherited and passed on within a cul-ture, such as oral traditions, performing arts, social practices, rituals, festive events, knowledge, and practices concerning nature and the universe or the knowledge and skills to produce traditional crafts (UNESCO 2017a).

Digital heritage includes valued knowledge or expressions that have been created digitally, or converted into digital form from exist-ing analogue resources (UNESCO 2017b).

Preservation is protection of cultural property through activities that minimize chemical and physical deterioration and damage and that prevent loss of informational content. The primary goal of pres-ervation is to prolong the existence of cultural property.

Conservation is the profession devoted to preservation of cul-tural property for the future. Conservation activities include exam-ination, documentation, treatment, and preventive care, supported by research and education.

Preventive care (also called preventive conservation) is mitiga-tion of deterioration and damage to cultural property through the for-mulation and implementation of policies and procedures for the following: appropriate environmental conditions; handling and maintenance procedures for storage, exhibition, packing, transport, and use; integrated pest management; emergency preparedness and response; and reformatting/duplication.

orsik@cosentini.com). Copyright ASHRAE 2024.

https://www.ashrae.org/about/position-documents https://www.ashrae.org/technical-resources/covid-19-one-page-guidance-documents https://www.ashrae.org/technical-resources/covid-19-one-page-guidance-documents https://www.ashrae.org/technical-resources/resources https://www.ashrae.org/technical-resources/resources https://www.ashrae.org/advertising/handbook-advertising/applications/museums-galleries-archives-and-libraries

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2. KEY CONSIDERATIONS

2.1 HERITAGE

“Heritage is our legacy from the past, what we live with today, and what we pass on to future generations. Our cultural and natural heritage are both irreplaceable sources of life and inspiration”

(UNESCO 2018).

Cultural heritage (tangible, intangible, and digital) is considered essential to the understanding and appreciation of humanity’s diverse cultures and history. The importance of cultural heritage may be na-tional, regional, or local, and it may have symbolic, aesthetic, cul-tural, social, historical, scientific, and monetary values that are frequently impossible to estimate. Thus, access to and preservation of cultural heritage is important and may even be legally mandated.

This chapter addresses preservation of tangible heritage: physi-cal objects such as books and documents, works of art, historic tools and utilities, archaeological artifacts, specimens of natural history, examples of popular culture, products of various technologies, and historic buildings.

2.2 CONTEXT

Objects are often held by various collecting institutions such as museums, galleries, historic buildings, libraries, and archives. These collections have different uses, depending on the institution’s mis-sion, and require specific management policies: in museums, the majority of a collection may be kept in storage with limited access, with a smaller portion on temporary or semipermanent display, often in showcases; in archives and libraries, almost all of the collections are in storage, from which they are pulled for research or exhibition;

historic houses have most of their collections on permanent open dis-play. Individual objects from collections may be on short- or long-term loan to another organization.

Collections may be housed in purpose-built buildings or existing buildings of historic significance; sometimes, the building may be as (or more) important than the collection it houses. Most collections have been housed in existing buildings with climate control ranging from nonmechanical strategies (e.g., thermal insulation, window shutters) to mechanical systems (e.g., localized dehumidifiers, full HVAC). As a result, collections have a specific climate history that should be taken into consideration when reviewing environmental strategies.

2.3 INTERNATIONAL STANDARDS

To facilitate loans, cultural heritage organizations often look to follow international guidelines on environmental control. It is there-fore important to be aware of the shift in thinking about sustainable collection management that is having a major impact on standards and guidelines. The U.K. National Museum Directors’ Conference (NMDC 2008) focused on a long-term, broad plan for minimizing excessive energy use in the care of collections, reducing museums’ overall carbon footprint. In turn, the International Group of Orga-nizers of Large-Scale Exhibitions (Bizot Group 2015) proposed a broader set of interim temperature and relative humidity guidelines for hygroscopic materials on loan, based on the NMDC proposal;

their goal was to simplify international loans, reduce costs, and decrease the carbon footprint. This prompted the Association of Art Museum Directors (AAMD) to request input from the conservation community.

As a response, the international professional organizations Inter-national Institute for Conservation of Historic and Artistic Works (IIC) and International Council of Museums—Committee for Con-servation (ICOM-CC) published a declaration on environmental guidelines (IIC/ICOM-CC 2014). It states This file is licensed to Lasz •“The issue of museum sustainability is much broader than the dis-cussion on environmental standards, and needs to be a key under-lying criterion of future principles.

• “Museums and collecting institutions should seek to reduce their carbon footprint and environmental impact to mitigate climate change, by reducing their energy use and examining alternative renewable energy sources.

• “Care of collections should be achieved in a way that does not assume air conditioning (HVAC). Passive methods, simple tech-nology that is easy to maintain, air circulation and lower energy solutions should be considered.

• “Risk management should be embedded in museum management processes.”

2.4 PRESERVATION AND RISK MANAGEMENT

Preservation of cultural heritage involves mitigating the impact of agents of deterioration (CCI 2018). It requires a trade-off among many factors and there is no single golden rule. Instead, risk man-agement approaches are used to arrive at an appropriate solution (see the section on Overview of Risks). For example, creating an environment for preserving the collection that causes problems for the building in which it is housed is not acceptable.

It is possible to substantially slow deterioration caused by envi-ronmental agents of deterioration, thus fulfilling a major function of the collecting institution. However, doing so may conflict with another important function of cultural institutions: allowing public and scholarly access. Additionally, extremely tight control over all environmental parameters comes at a price few cultural institutions can justify or afford. Managing risk, not avoiding it altogether, is the objective.

Climate-induced risks should be seen in context and relation to other risks to the preservation of cultural heritage, such as natural and human-caused disasters. Frequently, it is not the greatest risk to a col-lection, and available funds may be spent more effectively else-where. Therefore, it is fundamental that an institution develops an overall preservation strategy, of which its climate control is an inte-gral part, based on a comprehensive risk assessment. A climate-control strategy should complement mitigation plans for other risks and should not in itself create a greater hazard. Consequently, greater risk reduction can come from ensuring the reliability of the system, rather than controlling minor excursions from defined climatic ranges. Most threats to collection preservation, in fact, can be addressed by properly maintained housing and professional support.

2.5 SUSTAINABILITY

This chapter advocates environmental strategies and solutions for cultural heritage collections that support their access and pres-ervation in a responsible way (i.e., that are sustainable economi-cally, socially, and environmentally). It aims to inform strategies that sustain feasible climatic conditions for the foreseeable future and takes into consideration

• An organization’s mission and resources

• The needs of the collection and its users

• Building type

• Local, regional, national, or international policies

• Suitable environmental systems

To design and implement appropriate climate control for a specif-ic collection, it is important to involve all appropriate stakeholders, which can vary by institution but may include engineers, architects, facility managers, security staff, cultural heritage administrators, ar-chivists, collection managers, conservators, conservation scientists, curators, and registrars. Administrators are responsible for fiscal and political decisions, whereas collection managers and conservators are responsible for providing access and care of the collection. Cu-lo Horsik (lhorsik@cosentini.com). Copyright ASHRAE 2024.

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, I nc rators build the collection and design exhibitions. Registrars oversee the legal paperwork and administration related to collection manage-ment. Security staff is critical to safekeeping of the collection.

Therefore, a multidisciplinary approach is required to obtain a comprehensive overview of all aspects that impact an environmental management strategy, and some of this work should be carried out before an engineer is engaged in a project.

Cultural institutions frequently operate as nonprofit organizations on tight budgets with limited human and/or technical resources. In-sisting on best-available technology for extraordinary humidity con-trol or comprehensive pollutant filtration may endanger long-term fulfillment of the institutional mission.

From project inception, both the design objective and realistically available operation and maintenance resources must be considered.

Having reliable monitoring data is crucial in the decision-making process. Before embarking on full mechanical control solutions, efforts should be made to use or integrate strategies that do not rely on mechanical control, including passive building solutions and non-mechanical adjustments, which can successfully provide appropriate environmental control for the collection.

In accordance with the international call for reducing energy use and examining alternative renewable energy sources, solutions that can complement the local external climate should be explored first.

These include building envelope improvements; integrated strate-gies that address preservation, access, and human comfort needs;

hybrid systems (alternative energy sources); seasonal and diurnal adjustments; and enclosures providing microenvironments for indi-vidual or multiple objects.

3. CONTEXT AND PREDESIGN

Before an appropriate environmental management strategy can be developed, many contextual factors need to be considered. Cul-tural institutions vary not only in their geographic location and building morphology, but also in their purpose, mission, and the materials, condition, and needs of their collections. The values placed on different collections, their uses, and their expected life-times all influence an environmental management strategy.

This section addresses the process of developing sustainable environmental management strategies for different types of projects, from installing new or upgraded mechanical systems in new purpose-built or renovated structures, to more energy-efficient cli-mate control strategies in existing situations. Although there are sig-nificant differences between new purpose-built museums and historic houses, the decision points are similar.

A schematic decision-making flowchart can be used to define the necessary, broad steps from strategic plan to evaluation (Figure 1). It is intended for both new and existing buildings with a range of environmental solutions. The diagram also accounts for situations where there may be no collection preservation problems or the environment is deemed appropriate, but there is a desire to reduce energy consumption. The components/steps in the diagram are de-scribed in the following text. Although the later steps outlined in Fig-ure 1 are not within the scope of predesign, these sections describe considerations that can be addressed during the predesign phase.

Different projects require different amounts of time and re-sources for individual steps. For many cultural institutions, particu-larly those that have been operating for some time, relevant information such as collection surveys or significance assessments may already exist, reducing the time required for predesign. In all instances, however, decision making is a multidisciplinary activity involving a variety of stakeholders, whose role and level of involve-ment can change throughout the project. The list on the right-hand side of Figure 1 shows the expected level of participation for stake-holders at each step: if they are making decisions, if they should be This file is licensed to Laszlo Horsik (l consulted or be informed. If there is doubt, it is usually advisable to engage the stakeholders earlier in the process.

A design engineer may not be involved in the early stages of this process. All these steps, however, influence the choice and delivery of the environmental management strategy and include important information for considering appropriate goals and solutions. A new building may involve developing a strategic plan and mission before a building project is started, whereas an operating museum may engage an engineer to provide a solution to an identified problem or undesirable situation.

3.1 MISSION AND STRATEGY

The purpose of any cultural institution is central to all decisions, even if its influence is implicit. Almost all cultural institutions have a mission statement, even those where the building is yet to be con-structed. An operating museum often has statements of significance for collections, which describe the reasons for their importance. The mission of the institution and how its heritage assets are valued determines how the assets should be preserved and what is under-stood as a risk. The values of a collection directly inform the impact of a hazard, and even how different kinds of damage are regarded.

An archive values the informational assets of its collection, often allowing access to individual items by researchers, increasing the risks of damage caused by handling. A fine arts museum may value aesthetic appearances that are affected by minor damage. A library and a contemporary art museum will have different expectations of the lifetimes of their objects and how their values are embodied by the material. This concept is also addressed in the section on Con-text, under Key Considerations.

3.2 DETERMINE NEEDS

Although the collections are usually the principal focus for man-aging the environment in a cultural institution, the needs of occu-pants and of the building itself must be balanced (along with capital and operating costs). Historic buildings can often be more significant than the collections that they contain. The respective importance of these needs varies among institutions and even among spaces, and their requirements can conflict.

The differing needs of spaces in cultural institutions can be bro-ken down into broad categories of use by considering whether they contain collections, people, or both. This also helps identify spaces that can often be more flexible in terms of control, because there are many areas in cultural institutions that do not house collections, are not open to the public, and have occupancy for short and limited periods. Table 1 shows the kinds of spaces found in cultural institu-tions and what their use could imply through a matrix of occupancy levels for collections (columns) and people (rows). Spaces that house both often require the most consideration. Given that needs often differ between people and collections, the matrix presents opportunities to emphasize certain needs. Although specifics may vary over time (e.g., long-term uses, short-term management of spaces that are unoccupied at night), Table 1 provides some guid-ance of where resources are best applied. The specific collection needs must further be addressed in context.

Collection needs vary considerably with the kinds of materials, combinations of materials in a single object, and how the objects were made. Even library collections comprise a mix of materials to consider. Information about different materials can require specialist knowledge from conservation or science experts, some of whom may be external to the institution.

Relevant information to determine collection needs includes

• Materials

• Construction/assembly

• Condition and vulnerability (see Tables 2 and 13)

• Current and intended uses of the collection horsik@cosentini.com). Copyright ASHRAE 2024.

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• Frequency and kinds of access

• Specific climate history (and movement of objects over time)

Relevant information to determine building needs includes

• Materials and construction

• Condition and vulnerability

• Current and intended uses of the building

• History and changes to the building

Relevant information to determine human needs includes

• Numbers of staff and visitors and their current and/or intended activities

• Current and intended uses of spaces

• Expected kinds of clothing (which can vary in historic properties)

For a new institution, data gathering may involve plans and blue-prints, and collection policies, rather than assessments of specific collections, but information that can help determine needs can be found in a range of sources. In operating cultural institutions, a collection risk assessment and/or condition survey may have been carried out for the collection, which would include most of this information. Collection needs are described more comprehensively in the sections on Overview of Risks and Environmental Effects on Collections.

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3.3 CURRENT ENVIRONMENT

Analyzing and understanding the past and current environmental conditions in and surrounding the buildings, and the interactions among climates, buildings, people, and collections, is essential to de-veloping appropriate environmental management, even if no inter-vention is carried out in the cultural heritage institution. Information relevant to understanding the influence of the environment on the building, collection, and people includes climate zone and predicted climate change, site macrocontext and morphology, the building and its orientation, existing methods of environmental control, and mon-itoring data on each hazard (temperature, relative humidity, pollut-ants, and light) both indoors and outdoors. This often requires a year of data collection, particularly for seasonally affected parameters such as temperature and relative humidity. These data are collected regularly in cultural institutions, but the points of measurement, sam-pling interval, and reasons for monitoring should be reviewed. A building management system (BMS) may provide useful informa-tion about existing environmental management, particularly with re-spect to human comfort, but in general, climate monitoring should be independent from the system that is used to control climate, and it may be necessary for data to be gathered close to objects.

Other contextual factors to consider include staff, their roles, institutional policies, operating costs, and energy use, as well as an institution’s budget. Each institution should seek to understand its Fig. 1 Decision Diagram for Environmental Management Strategies in Museums, Galleries, Archives, and Libraries (based on Taylor, forthcoming)

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Table 1 Examples of Space Types in Museums, Galleries, Archives, and Libraries

Collection Noncollection

Public space Changing exhibition galleries Entrances/vestibules Permanent collection galleries Atria Reserve/scholar collections Cafeteria Open storage Restaurants Most reading/collection study rooms Shops

Auditoria Education spaces Restrooms Coat/baggage rooms

Nonpublic space Conservation laboratories Offices Collection storage Crate storage (controlled relative humidity may be required) Workshops and mount-making areas Mechanical/electrical rooms Archive stacks Data centers/IT rooms Library stacks Food preparation areas Quarantine areas Loading bays Photography studios Digitization areas

Low-occupancy space* Cool and cold storage General storage areas (sales shop inventory, event equipment, etc.)

Low oxygen storage Low-relative-humidity rooms Off-site storage (e.g., high-density library stacks)

*Occupancy in these spaces is for short periods, and meeting human comfort standards may not be required.

Notes:

(1) Collection spaces and adjacent noncollection spaces often require substantially different types of control. Providing barriers (e.g., doors, air curtains) to limit airflow and mois-ture vapor exchange between these spaces is usually necessary for successful control.

(2) As exhibition needs change and collections grow, it is common for noncollection areas to be repurposed for collection exhibition. It is important to keep this in mind when plan-ning HVAC systems. A café or atrium may not require relative humidity control or special filtration, but if the space is repurposed to exhibit objects that require specialized envi-ronments (relative humidity control, etc.), retrofitting a system to provide the appropriate environment can be costly and disruptive.

(3) Objects may be displayed in noncollection spaces through careful object selection (e.g., statues in vestibules) or use of display cases with the necessary microclimate perfor-mance. Offices that display collection items, such as paintings, should apply the same preservation requirements as collection spaces. Classrooms or other education spaces may be used to house some collection objects for extended periods; if so, collection-appropriate environmental control may be required.

pattern of energy consumption and recognize the most energy-intensive activities, which usually include lighting; appliance use;

and mechanical ventilation, heating, and cooling. The sampling interval for monitoring energy use should be short enough (typically 1 h or less) to evaluate daily energy consumption patterns. Energy consumption should be evaluated according to existing national or international regulations, and compared with existing benchmark-ing systems or, if no benchmarks are available, with energy con-sumption in similar cultural institutions. For further discussion on environmental context, see the section on Climate Loads.

3.4 OVERVIEW OF RISKS

The impact of the environment on materials can only be under-stood when both the environmental conditions and material proper-ties are known. By connecting preservation needs to materials’ responses to environmental conditions, expected changes can be un-derstood. Considering information about the institution’s values and assets along with material change clarifies decisions about future risk and priorities. Synthesizing the impact requires an overview of which factors are most important and how the collections are affected by the building and people, and vice versa; mitigating risk to one aspect may increase risk to another. Integrating the information allows a compre-hensive definition of the situation, because criteria vary between in-stitutions: for example, historic houses may place more emphasis on preserving the building than a new museum might.

Understanding this impact allows comparison to other general risks (see Table 2). Developing this overview allows an institution to prioritize needs, allocate resources, and develop goals for the development of a strategy. Much of this information may already exist in the form of a risk assessment. For further discussion of col-lection risks, see the section on Overview of Risks.

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3.5 ACCEPT OR MODIFY ENVIRONMENT

Once information has been gathered and synthesized, modifica-tions to the environment may be considered. If the current environ-ment is appropriate for the institution’s identified needs, goals, and resources, the most appropriate decision can be to do nothing at the present time and continue monitoring. Other priorities in the insti-tution may take precedence.

For an operating institution, changes to existing building man-agement and/or modifications to the building envelope may be appropriate ways to address the identified risks or high energy con-sumption. Problems can be addressed without directly modifying the environment, by adjusting locations and activities such as changes in circulation patterns, use of selected spaces, and exhibi-tion policies. Dividing collections by material type is a common measure, particularly in storage locations. When planning a new building, managing the risks most relevant to the institution’s mis-sion should be addressed early, with careful consideration of build-ing morphology, envelope characteristics, and expected energy use, as recommended by the International Institute for Conservation of Historic and Artistic Works and the International Council of Muse-ums Committee for Conservation (IIC/ICOM-CC 2014).

Environmental modification may involve direct intervention, either mechanical or nonmechanical; passive design measures are also available. There is no risk-free scenario, and any decision must take into account available resources and the impact on the institu-tion as a whole, as well as overall environmental impact. Even after the initial diagnosis of risks, it is likely that this consideration may require further investment and expertise before a final plan can be developed.

Regardless of how big or small the expected changes to the envi-ronment or management, monitoring should be carried out to fur-ther investigate problems or check for simple solutions.

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For related information, see the section on Preservation and Risk Management.

3.6 ANALYZE/PREDICT ACHIEVABLE

ENVIRONMENTS AND IMPEDIMENTS

If it is decided that a comprehensive solution is required, further analysis (e.g., diagnostic monitoring, hygrothermal modelling of in-door spaces, deeper investigation of existing control methods) will be necessary. Assessing information already gathered indicates what environments can realistically be achieved in a given climate zone with existing control methods, or the expected impact of proposed changes in the building envelope or type of environmental control.

Comparing what environment can be achieved in the current or planned space with what is identified as necessary for collection preservation indicates the kind and level of intervention that is appropriate. This could include energy-saving options where a col-lection’s sensitivity is lower than the tightest level of control that can be managed (see Tables 13A and 13B), or a new approach to envi-ronmental management in the institution. For new buildings, this step presents an opportunity to consider appropriate parameters and objectives for different needs in the proposed spaces based on their (potentially mixed) use.

The sections on Environmental Effects on Collections and on Design Parameters for Performance Target Specifications contain further discussion of environment and impediments.

3.7 SET PARAMETERS AND OBJECTIVES

Understanding what is required to sustain the collection over time, and to ensure access to and use of the collection, is essential.

Knowing the resources necessary to accomplish this, as well as what is achievable with the building envelope, the environmental param-eters can be agreed upon. The expected lifetime of a collection, or its desired rate of deterioration, can be reviewed at this point, which may require input from a conservation scientist. Many collections comprise a mix of materials with differing preservation qualities. If a collection largely comprises a limited range of materials, or if materials can be easily separated from one another, specific infor-mation about the responses of those materials to environmental con-ditions can be directly applied. If the collection has been in the same environment for a long time (usually longer than 10 years), it will have had time to acclimatize to those conditions. Tables 13A and 13B provide information on the expected implications (outcomes) of different kinds of climatic control for mixed collections.

These parameters also must take into account human comfort (see ASHRAE Standard 55-2017) and cost implications.

The sections on Environmental Effects on Collections and on Design Parameters for Performance Target Specifications contain further discussion of parameters and objectives.

3.8 DEVELOP OPTIONS

How the environment is managed (according to agreed-upon pa-rameters and objectives) has multiple implications, not just for the collection and costs (financial and energy consumption), but also on facility operations. Even in small interventions, staff should have ac-cess to the information because simple measures can affect other ac-tivities, such as security or audience engagement events. A clear understanding of the resources available, including budget, staff roles, time, training, and space, is needed for control options to be de-veloped and evaluated.

For a new building, the solution may be part of a larger, inte-grated approach. HVAC design options should first consider the building as a means of control (see Tables 12, 13A, and 13B).

For more details, see the section on Design Parameters for Per-formance Target Specifications, and ASHRAE Guideline 34-2018.

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3.9 REVIEW OPTIONS AND SELECT

Many criteria may be involved in selecting the most appropriate approaches to environmental management. A method to determine consensus should be decided upon, and the key stakeholders for the project identified. All staff affected by environmental management should be consulted (or represented) in terms of how the options meet the chosen criteria. This is often best carried out through facil-itated, recorded meetings where criteria are addressed systemati-cally and transparently (Cassar 1995). Such processes present the opportunity to examine different perspectives and resolve apparent conflict through discussion. Results should be archived for future reference.

Criteria for evaluating approaches to environmental management may well go beyond collection preservation and cost, to include is-sues such as impact on historic building fabric and human comfort.

For example, historic houses can be adversely affected by installa-tion of mechanical systems. A cultural institution’s mission state-ment can be a useful reference point to weigh the importance of criteria. This stage distills much of the information gathered earlier in a clear, digestible form for all stakeholders, so informed decisions can be reached collaboratively.

3.10 PREDESIGN PROGRAM BRIEF

This is an opportunity for owner’s requirements to be defined be-fore the solution is designed, including approach, scope, design team, and timeline. In some cases, a design engineer might not be en-gaged until after creation of the program brief.

While setting criteria for the design team, solutions outside the scope of the design team (e.g., housing objects in display cases or archival boxes) should be part of the overall project effort. This again allows project goals to be aligned with the institution’s wider mission and other goals. A range of stakeholders already engaged in the process will be involved in planning and construction, so a clear shared vision helps the cultural institution work through the devel-opment.

3.11 DESIGN OF SOLUTION

Although design of the solution is discussed more comprehen-sively later in the chapter, some considerations can be addressed during predesign. All needs identified while developing the prede-sign program brief should be communicated, and a liaison with col-lection and building staff should be identified. The solution may not yet be designed, but if the general approach is known, decisions can be made about whether to move collections before work begins.

Rehousing a collection requires considerable time, including measures for documentation (e.g., database, photography, radio-frequency identification [RFID]) and security, as well as environmen-tal management. If the collections are not being moved, preparation for extra protection may be needed during an implementation phase.

Depending on the approach, projected growth of the collection may also be a consideration during predesign.

3.12 PROCUREMENT AND CONSTRUCTION

Procurement and construction are discussed in more detail later in the chapter, but there are opportunities to prepare for this stage. A risk assessment may be required for the designed solution (espe-cially if the collection is moving). Information from the context and predesign phases about the values of the collection and building is relevant and should be accessible. For larger projects, a dedicated collections professional responsible for oversight of collections preservation issues during construction may be engaged.

Cultural institutions often have historic buildings that are intended to last for a long time. The life cycle of materials, and any impact of the solution on historic values, should be understood by all parties.

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3.13 START-UP AND COMMISSIONING

Commissioning and start-up are discussed later in the chapter. A commissioning agent should be identified and engaged during final predesign and early design stages, so they understand the underly-ing design goals and can be present through the process.

3.14 TRAINING AND DOCUMENTATION

Training and documentation are discussed later in the chapter, but the data gathering that has already occurred should be instruc-tive to this process. Understanding and documenting current man-agement and maintenance practices can help communicate in-house skills and expertise to the design team. Time during a project may need to be put aside for training, and a realistic understanding of institutional and staff capacity is required before implementing a design option. Staff changes over the time horizon of larger projects may also need to be considered.

3.15 EVALUATE AND REVISE

This step is addressed later in the chapter, but data gathered at any early stage can help serve as a baseline for evaluating the solution, and should be documented and archived for future reference. This includes data on climate and pollution as well as energy costs. How environmental monitoring is carried out during predesign should inform continued monitoring beyond implementation of the solution.

4. OVERVIEW OF RISKS

A collection’s longevity is directly influenced by the building’s architecture, any climate control systems (nonmechanical or me-chanical), and existing preservation procedures and protocols.

These may positively mitigate the impact of risks or, alternatively, exacerbate them. Mechanical engineers need to consider the risks for collections even if they do not appear to relate directly to a build-ing’s mechanical systems. The hazards listed in Table 2 are called agents of deterioration in the conservation field and may affect collections. Note that there can be interactions between different agents of deterioration, and many hazards are created by several agents in conjunction with one another (CCI 2018). Assessments are often used to identify the potential impact or magnitude of a risk occurring.

Any climate control strategy should complement mitigation strategies for other risks and should not in itself create a greater haz-ard (e.g., when an energy supply fails, or when an active HVAC sys-tem spreads fire or soot if no automatic HVAC shutdown is provided).

Table 2 does not cover natural emergencies, which are often dev-astating and have effects beyond the institution. Institutions (should) have emergency response policies in place to deal with incidents, emergencies and disasters.

5. ENVIRONMENTAL EFFECTS ON

COLLECTIONS

Providing specialized temperature and relative humidity control has been central to museum, gallery, archive, and library design since the nineteenth century, and numerous architectural and HVAC solutions have been explored. Luciani (2013) provides a detailed history of these engineering and architectural solutions throughout the twentieth century in North America and Europe. Until recently, temperature and relative humidity specifications were based on cau-tiously applied qualitative understanding (Michalski 2016), rather than quantitative understanding applied to decisions influenced by sustainability. This section summarizes the technical knowledge available to support current decisions, particularly when selecting or modifying targets.

This file is licensed to Laszlo Horsik (l

5.1 BIOLOGICAL DAMAGE

High relative humidity levels and dampness accelerate mold growth on most surfaces. Of all HVAC-controllable environmental parameters, high humidity is the most important factor.

The most comprehensive mold data are from the feed and food lit-erature. Fortunately, this provides a conservative outer limit to dan-gerous conditions. Mold on museum objects occurs first on surfaces contaminated with dust, sugars, starch, oils, etc., but can also occur on objects made of grass, skin, bone, and other feed- or food-like materials. Water activity is identical to and always measured as the equilibrium relative humidity of air adjacent to the material. This provides a better measure than the equilibrium moisture content (emc) for mold germination and growth on a wide variety of materi-als (Beuchat 1987). Figure 2 shows the combined role of temperature and relative humidity. A study by Groom and Panisset (1933) of the most vulnerable book materials concurs with the general trend of culture studies from Ayerst (1968) and comprehensive data on mold growth in buildings obtained by Sedlbauer (2001). Ohtsuki (1990) reported microscopic mold occurring on clean metal surfaces at 60%

rh. The fungal DNA helix is known to collapse near 55% rh (Beuchat 1987), so a conservative limit for no mold ever, on anything, at any temperature, is below 60% rh. Chapter 26 suggests a similar lower boundary to avoid mold in food crops.

Snow et al. (1944) looked for visible mold growth on materials inoculated with a mixture of mold species. These are plotted in Fig-ure 3, and follow the same trend reported by Hens (1993) for the European building industry for wall mold.

Figures 2 and 3 show practical dangers: growth in less than a sum-mer season requires over 70% rh, and growth in less than a week requires over 85% rh. Care must be taken to avoid cold surfaces where condensation might occur, such as on windows and ductwork.

There are relatively few experimental data on the relationship between the risk of insect infestation and climate parameters (Strang 2012). Child (2007) and Pinniger (2001) suggest that, below 59°F, pests that can damage cultural heritage collections start to be sluggish and do not fly. Also, low relative humidity further limits pest risk because eggs and young larvae are sensitive to dehydration.

Child (2007) reported that the furniture beetle (Anobium punc-tatum) require relative humidity levels above 60% to reproduce. A risk index quantifying the threat of pest infestation was proposed by

Fig. 2 Temperature and Humidity for Visible Mold in 100 to 200 days horsik@cosentini.com). Copyright ASHRAE 2024.

laszlo.horsik Highlight so a conservative limit for no mold ever, on anything, at any temperature, is below 60% rh laszlo.horsik Highlight High relative humidity levels and dampness accelerate mold growth on most surfaces. Of all HVAC-controllable environmental parameters, high humidity is the most important factor.

laszlo.horsik Highlight The fungal DNA helix is known to collapse near 55% rh (Beuchat 1987),

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Table 2 Agents of Deterioration: Potential Hazards in Managing Collection Environments

Agent Comments

Physical forces Handling, shock, and vibration can cause immediate or accumulative long-term damage to fragile objects.

Risks often increase during construction work, when collections may have to be relocated or secured in situ.

Mechanical systems may present a risk if vibration is transmitted through ductwork to works hung on adjacent walls or in particularly active air drafts.

Vibration transmitted to objects may cause them to move, and to fall off of exhibit and/or storage shelves.

Thieves and vandals Can be addressed by limiting access to mechanical systems to improve security.

Fire* Fire (and its related methods of extinction) can result in serious damage or even total loss of building(s), collections, operations, and services.

Fire prevention and control, aimed at reducing the risk of a fire occurring and minimizing its effects, should be given the highest pri-ority possible.

It is recommended that each HVAC system be integrated with a fire detection system, ensuring that the system is shut down in a fire alarm to limit the spread of fire, smoke, and soot.

Water* Liquid water (including rain, flood water, or water from broken pipes) is often related to incidents and disasters, but also includes dampness resulting from condensation and rising damp in buildings.

Liquid water is very destructive to collections: it can stain, deform, or even dissolve materials.

Wet conditions can quickly germinate mold, fungi, and bacteria, creating hazardous conditions for human health.

Pests Infestations primarily include insects devouring collections; mold, fungi, and bacteria also qualify as pests.

Limitation measures include avoiding high relative humidity and warm conditions, maintaining overall cleanliness, and controlling indoor air quality and ventilation (which helps reduce temperature gradients and thus relative humidity).

Pollutants (or contaminants)

Includes outdoor-generated gaseous and particulate contaminants that infiltrate the building and indoor-generated gaseous pollutants.

Sources and effects of pollutants are detailed in the section on Airborne Pollutants/Contaminants.

Particulate filtration to control both coarse and fine particles and gaseous filtration is discussed in the section on Airborne Pollutant Control Strategies.

Light (or radiation) Most materials undergo some form of permanent photochemical or photophysical change from exposure to radiation (i.e., visible, infrared [IR], and ultraviolet [UV] light), which is an inevitable consequence of display.

Light damage is cumulative but relatively easy to control if addressed at architectural, design, and operational levels by eliminating ultraviolet radiation, minimizing infrared radiation, and limiting light exposure by decreasing illumination intensity or its duration.

Temperature When temperature increases, damaging chemical processes accelerate.

Any temperature change affects the absolute humidity in the air, resulting in changes in relative humidity.

Relative humidity and temperature are often considered together when deciding on a climate control strategy, especially for suscepti-ble classes of materials such as early synthetics (plastics), paper, and photography.

See the section on Temperature and Humidity for details.

Relative humidity Each organic/hygroscopic material has a specific level of moisture content consistent with maximum chemical, physical, or biological stability.

Relative humidity becomes a risk factor when it causes the moisture content in a material to be significantly too low or too high.

Fluctuating relative humidity with large and prolonged variation in levels can also be damaging, specifically to objects of composite materials and/or restrained constructions.

Inorganic (nonhygroscopic) materials can also be adversely affected by moisture in the air (e.g., corrosion of metals, salt efflorescence in porous materials).

See the section on Temperature and Humidity for details.

*Fire and water are often associated with building and mechanical (design) malfunctions, such as power outages, electrical short circuits or water pipe failure (especially over spaces containing collections).