This is the third article in a series by Jon Huddy, ED architect and author of ACEP’s ED design book, offering insights to you as an ED physician leader on how to position your emergency department for architectural design success.  The previous articles focused on how and why you need to position yourself to be placed on key committees that will make early, impactful decisions on your potential ED project.   This article focuses on the numerous ways “square footage” is calculated to quantify space so that you are clear on “what your ED is gaining” with a proposed ED design project.

Not Every Square Foot is a Square Foot

Let’s start with a scenario where your hospital’s Director of Facilities tells you that you are approved for 10,000 square feet building expansion for the Emergency Department.  Sound’s good, right?  After all, it’s been years since you updated the ED and any expansion sounds wonderful.    The downside is that you may not be aware that the generic term “square feet” when applied to a building project doesn’t necessary mean that you will gain 10,000 square feet of ED space.

Let’s discuss the complex nature of how square footage is calculated during an ED design and construction project.   The title of this article “A Square Foot of New Construction May Not Mean a New Square Foot of ED Space” hints at the fact that square footage terminology can be confusing and may not deliver all of the “space” that you believe was promised.    You will hear terms like net square footage, departmental gross square footage, building gross square footage, and square footage “multipliers.”   All of these terms are applicable to a design project and they all quantify a different amount of actual “ED patient care space” based on how they are calculated.   It’s very important that you understand the differences between these square footage terms so that you can understand what is being designed and what will be delivered for actual emergency department space.

Net Square Footage

Net Square Feet (NSF) is the area “within” a given room or space.  It is measured from inside wall to inside wall, or from designated boundary to designated boundary (such as in a nurse station).  A room 10 feet wide and 12 feet deep would have 120 NSF.  A nurse station 20 feet wide by 15 feet long would have 300 NSF.  Individual NSF calculations are applied to each room or space that is utilized for a specific function and may be applied to public spaces, clinical treatment spaces, support areas, administrative areas, storage rooms, toilets, etc.   A Space Program is a term that architect’s use to define the list of “usable spaces” that will be included in your ED.  The Space Program will identify each room/space, the quantity that will be designed, and the applicable Net Square Footage for each usable room or space.  The Space Program will show a sub-total for all of these spaces added together, thus quantifying the total Department Net Square Footage (DNSF).   It is important to understand that the DNSF calculation does not include circulation spaces, such as hallways or corridors.   Also, DNSF does not include all of the wall thicknesses that define the rooms and spaces, nor does DNSF include the mechanical, electrical or plumbing shafts that may run through your ED space (from floor below to floor above) behind the walls within your department.

Departmental Gross Square Footage

The term that quantifies all of the space you need within your department including the NSF area, wall thicknesses, corridors, mechanical/electrical/plumbing shafts, etc. is Departmental Gross Square Feet (DGSF).   Think of looking at a floor plan diagram and running a line around your entire department on the inside wall of all perimeter walls that define your ED (whether those walls are exterior building walls or a wall that defines the extents of your department inside the hospital.)   All of the area within this “border line” around your department is the Departmental Gross Square Footage of your ED.

Department Net to Gross Multiplier

When Huddy HealthCare Solutions develops a space program, we use a 1.55 “net to gross multiplier” for our ED projects.   What this means is that we take the Space Program that lists the  Department Net Square Footage of all rooms and spaces and multiply that DNSF by 1.55 to quantify a total Department Gross Square Footage.  We find that it takes 55% more space than the DNSF to accommodate all circulation spaces, corridors, rooms, walls, shafts, etc. to design a fully functional, flexible department.   By example, a Space Program listing individual rooms and totaling 20,000 Net Square Feet will need an area of 20,000 x 1.55 = 31,000 Departmental Gross Square Feet to accommodate all rooms, spaces and circulation within a designed area to design the ED.     But, be careful, because DGSF does not include the area needed for exterior building walls, mechanical equipment rooms, electrical equipment rooms, communications closets, and other components that you need to complete an ED building expansion.

Building Gross Square Footage

Building Gross Square Footage includes all of the Department Gross Square Footage plus an allocation of additional square footage for exterior walls, additional mechanical/electrical/communication equipment rooms (some of which may be on the roof or in a basement), elevators, stairs, etc. that would make-up a typical building expansion that may have multiple floors.  When programming Building Gross Square Footage for a healthcare building, the typical area calculations include the “DGSF multiplier” of 1.25 for a single story building expansion (no stairs, no elevators) or “DGSF multiplier” of 1.35 for a multi-story building (to accommodate for additional square footage for stairs and elevator towers in a multi-level building addition).  So, a departmental gross square footage of 10,000 square feet (single story) would need an estimated 10,000 x 1.25 = 12,500 Building Gross Square Footage to accommodate the Departmental Gross Square Footage needed to deliver the ED space.

So Why is All of this Square Footage Talk Important to You?

Let’s go back to the beginning of this article when facilities director told you that you are getting an ED building expansion of 10,000 square feet.   In this scenario, he was thinking 10,000 Building Gross Square Footage, which includes mechanical/electrical rooms, etc.   If you divide 10,000 BGSF by 1.25 you end up with 8,000 Departmental Gross Square Feet for the entire emergency department boudary.   If you want to know the Net Square Footage of the new “usable space” that you will gain for the ED then divide by another 1.55 and you end up with 5,161 Net Square Feet.   Huddy HealthCare assists our physician clients in understanding the programming and design process so that everyone is clear on what is being delivered for a new or renovated ED project.   We work to maximize the delivery of “usable clinical space” so that each ED environment can maximize throughput and increase capacity.

You don’t need to get an architectural degree or a contractor’s license to understand these terms, but you do need to always be clear on what someone means when they utilize the generic term “square footage.”

Avoid Answering this Question:  Is 50% More Space Enough?

I have been involved in over 300 ED projects across the US, Canada and Europe, and I always recommend to my physician clients that they should avoid answering questions about how much space they need in the future ED.  This question may come from a senior administrator or a facilities director in the form of, for example, “you have 15,000 square feet now in your ED, would 7,500 more square feet be enough if we expand the ED?”  (First, as stated above, find out WHAT square footage they are quoting).

Seems like a harmless, and even helpful, question.  Many times ED physician leaders that are venturing into their first ED expansion project automatically link “amount of space” with “quantity of treatment spaces” such as “50% more space should deliver 50% more treatment spaces.”   In almost ALL scenarios, this is not the case, and for the reasons listed below, you should avoid answering the question “is ‘X’ amount of additional square footage enough for your future ED” until you thoroughly understand what the ‘X’ amount of square footage will deliver.

Building Codes and Minimum Standards

If your current ED was designed and constructed more than 10 years ago then it most likely was designed under a previous, and out of date, building code.  If you’re like most EDs that haven’t been updated in 15 or 20 years than the ED you work in was designed under a building code that has been updated multiple times, including requirements for larger spaces and new spaces not in your current ED.  One example is the requirement in most locations for a Bariatric Treatment Room which could be close to double the size of a standard exam room.   In nearly all states, across Canada, and in Europe, building codes and minimum planning standards (room size/configuration) have been updated for the design of the rooms and spaces that make up an emergency care facility.

In addition, new building codes that regulate the design of healthcare facilities have changed in many ways that will impact an ED including reduced exit path corridor lengths (“means of egress”), air-changes (that may affect the size of engineering mechanical rooms to provide the air capacity), electrical/communication rooms, and multiple other space requirements. All of this “code talk” means that you won’t be able to just duplicate what you currently have in your ED if you add more space… and I am guessing that duplicating what you currently have is the furthest thing from your mind!


The term “grandfathering” with regards to codes/standards means that the state/province/or national health system, such as the UK’s National Health Service (NHS), has allowed you to continue to deliver care in an ED that no longer meets current building codes or planning recommendations because the facility was originally designed to meet the applicable codes at the time of its construction.   Your current design is “grandfathered in” and allowed to continue to operate in its current condition… until you start to renovate the ED!

In nearly all jurisdictions, when you renovate a part of the ED you have to design and build to the most recent building code or planning guidelines.  And, in many jurisdictions, you will have to bring the entire area (i.e. total ED) up to current regulations, including areas you didn’t plan on renovating.   Why is this important to you?  Because the renovation of your current space may dictate larger rooms, more support spaces, more toilets, etc. and the end result is that you end up with LESS treatment spaces than you started with prior to renovations.

Let’s use the following project sample:   An existing ED has 15,000 Departmental Gross Square Feet and has 30 patient care spaces which consists of multiple small curtain cubicles, cramped semi-private exam rooms, small resuscitation rooms, and even a few hallway stretchers.  The current ED has limited storage and only a few patient bathrooms.

The proposed building expansion project is targeting a 7,500 addition which will deliver 50% additional space for the ED.   The plan is to build the expansion and then renovate the current ED so it is all one, flexible ED environment.   When the design is completed for the addition and the renovation of the old ED you review the proposed design drawings and realize the following:

  • When designed to current codes, the new 7,500 sf addition is going to deliver 10 new, private exam rooms.
  • As you review the drawings for the complete renovation of the old ED, you realize that when designed to updated codes you are going to get 20 new patient care spaces, which includes updated exam rooms and resuscitation rooms… but you only get 20 spaces!
  • You add the 10 new rooms with the 20 renovated rooms and the 30 total patient care spaces is equal to the total patient care spaces you had in the old ED.  Yes, you have eliminated hallway stretchers, eliminated curtain cubicles and have large, private patient care spaces.  But in the end you have no ADDITONAL CAPACITY!

This simplified scenario shows that you should do your best to avoid answering a question that wants you answer if any amount of square footage is enough for a future ED.   Let administration and facilities know that you don’t focus on square footage, but rather you want the project to focus on delivering additional patient care capacity, an environment that supports new, streamlined operations, and a future ED that will increase patient satisfaction.  And, that only going through the design process will you be able to answer a question regarding “how much square footage will be enough.”

Huddy HealthCare’s ED Design Team works with each ED physician team and staff to strategize a project plan to increase patient care space and maximize capacity.   Every project, no matter the size, can be designed to increase patient care space in way that meets any budgetary restrictions.   The key to a successful ED design is to focus on how to use the allocated space to “get what you need” in your future ED.

Needs Assessment

My next article will identify key components to analyze in your existing ED so that your organization is clear on your “current conditions.”  This assessment will assist you in defining true needs for your future ED project so that you can clearly prioritize what needs to be renovated, expanded, or created to deliver your vision of an ED of the future.

Please contact Jon Huddy directly should you have any questions, comments, or would like any additional information on the topic of correctly sizing an ED project to gain maximum results.

Jon Huddy can be reached at (803) 517-7522 or