Insulation and Drywall

Insulation

Insulation completes the rough-in stage of the house. It and drywall mark the transition between focusing on the structure of the home to focusing on the details.

Spray foam in the ceiling

To ensure a tightly sealed home, we had foam sprayed into the places where ceiling joists could expose a gap to the exterior, e.g., the ends of ceiling joists that extrude outside and the center beam of the roof. Foam was also sprayed onto some of the foundation walls that protrude into the interior.

Insulation batts

Next the insulation batts went in. All of the batts are formaldehyde-free fiberglass. We insulated all of the interior walls with R-11 and R-13 for sound deadening (more on our soundproofing). This is enough insulation to stop some sound, but not enough for heat insulation. The external walls use R-21 insulation for better thermal control. Insulation was installed throughout the house, including under the floor in the crawlspace and the garage.

Drywall

Drywall starts the interior finishing stage. It covers up the bones of the house, and provides a blank canvas for the interior.

The drywall process is complex. The goal is to achieve flat, seamless surfaces for the walls and ceiling. The quality level of the drywall, from 0-5, specifies how flat and level it is. Level 3 is about the minimum you'd want inside a house, and level 4 is probably more normal for quality construction. Our house is getting level 5 drywall throughout, which allows us to avoid any texture on the wall. Instead, we have a smooth surface that will just be covered with paint. This increases light reflection, especially in windows up against the ceiling where the light may be coming in nearly parallel to the drywall surface. Wikipedia has more details about all the levels.

Getting this level of smoothness takes many steps:

1. 

   Floor markings indicating what's in the walls and ceilings

   Level the studs: The studs need to be level enough to avoid creating bows or bends in the drywall. In our case, at least one stud had to be removed and replaced because it was warped.

2. 

   Drywall, just hung.
   Notice the roughness of the corners and seams.

   Hang the sheetrock: Boards are cut and screwed in to the studs such that all of the walls and ceilings are covered by the sheetrock. Holes for lights, outlets, vents, and any other openings in the wall are cut at this stage. Since it is easy to lose items behind drywall, the installers marked everything out on the floor before any sheetrock went up.
   The sheetrock at this stage is pretty rough. Edges, especially corners, can be uneven. Screws are sunk a bit into the drywall, making small depressions. There are gaps between sheets and around cut-outs. It looks like a bunch of panels stuck on the walls. This makes the rooms feel a lot smaller than before.

3. 

   Tape and mud

   Seal the gaps: The next step is to seal up all the gaps and start evening the surface. This is done using mud, tape, and corner strips. Mud is put in-between the gaps in the sheetrock, and tape is embedded to provide some structural support. Particularly for inset corners, the tape helps to make a sharp right-angle. Mud is spread lightly over the screw holes to bring them up to level with the sheetrock. Corner strips are used for outset corners. These are a thin piece of metal at a right angle, with some tape over that. Putting these over outset corners and applying mud covers up the rough edges of the drywall, and provides a sharp, clean corner. At this point, the walls start to look more coherent, and the space opens up a bit.

4. 

   Corners and more mud

   More mud: Two more layers of mud are applied as-needed to level everything out, especially the corner strips and tape, which may have slight raised edges otherwise. The edges of openings, such as can lights, are covered and leveled with mud. Each layer of mud needs to dry, so the house is warmed up and let sit for a day or two.

5. 

   The smoothing layers

   Smoothing coats: The final step is to add two full coats of material to smooth and level the dry wall. This was done using Smooth-Wall, a spray-on self-leveling coating that brings the drywall up to level 5. It serves as a polyvinyl acetate (PVA), which provides a basic primer coat, and makes everything a uniform material. These coats are just a primer and leveler, so the walls aren't meant to look perfect. There is a slight variation in color due to the drywall, and a slight texture on the walls. Both of these will be cleaned up with a couple layers of paint.

At this point, the walls and ceilings become a single smooth, level piece. The rooms are well-defined, and the surface looks very close to its final state. The perspective of the rooms change a bit; the ceiling height on the main level is more apparent, as is the shape of the soffits, columns, and doorways. The walls are now ready for paint.

Site Layout

Patterns made relatively few contributions to our general site layout. The shape of our lot, its relation to the street and utilities, and the setbacks and easements imposed by the city combined to make the placing of our house fairly obvious: our house would be at the east end of a long east/west oriented lot. Fortunately, these constraints ended up being fairly consistent with what we wanted out of the site layout patterns. (As before, problem descriptions and solutions -- the first two bullet points of each section -- are from A Pattern Language.)

Site repair (104):

• Problem: Buildings must always be built on those parts of the land which are in the worst condition, not the best.
• Therefore: On no account place the buildings in the places which are most beautiful. If fact, do the opposite. Consider the site and its buildings as a single living eco-system. Leave those areas that are the most precious, beautiful, comfortable, and healthy as they are, and build new structures in those parts of the site which are least pleasant now.
• For our home: The site naturally lent itself to fulfilling this pattern. Our lot is one portion of what was once a larger lot. The east side of our property had been disturbed by the construction of two new homes to the north. The west side is mostly wooded and partially a buffer zone for a nearby critical slope. Based on these constraints, it was natural to leave the wooded area intact and build on the disturbed land.

South facing outdoors (105):

• Problem: People use open space if it is sunny, and do not use it if it isn't, in all but desert climates.
• Therefore: Always place buildings to the north of the outdoor spaces that go with them, and keep the outdoor spaces to the south. Never leave a deep band of shade between the building and the sunny part of the outdoors.
• In our home: Our site is long east-west and short north-south, so we do not have a lot of flexibility for north/south siting. Part of the southern side of the property is taken by easements for a pedestrian path and for utilities. We have trees along the south western edge of our property, which decreases the amount of sunlight available. Despite the difficulties, we still have a sunny front yard in the east and a backyard in the west filled with tree-filtered sunlight. Neither requires going through deeply shaded areas for access. The shaded north side will be a terraced path down to the back yard.

Main entrance (110):

• Problem: Placing the main entrance (or main entrances) is perhaps the single most important step you take during the evolution of a building plan.
• Therefore: Place the main entrance of the building at a point where it can be seen immediately from the main avenues of approach and give it a bold, visible shape which stands out in front of the building.
• In our home: The location of the main entry was constrained by where we could put the garage (only on the north side). The garage also causes the entry to be nestled in instead of standing out in front of the building. We adapted to this difficulty and the site's natural elevation change by adding a large, bold stairway down to the front door. This extends the entry out so that it can be seen from all three approaches (driveway, sidewalk, and pedestrian path).

Entrance transition (112):

• Problem: Buildings, and especially houses, with a graceful transition between the street and the inside, are more tranquil than those which open directly off the street.
• Therefore: Make a transition space between the street and the front door. Bring the path which connects street and entrance through this transition space and mark it with a change of light, a change of sound, a change of direction, a change of surface, a change of level, perhaps by gateways which make a change of enclosure, and above all with a change of view.
• In our home: The design and placement of the entry were a good start for this pattern. The entry stairs (on the left in the image below) provide a natural change of level, material, and view. However, we need to make sure that this connects to all of the approaches. To aid in this, we are planning on adding some stairs from the sidewalk to the entry. These will provide a connection and allow us to add landscaping to further emphasize the sense of transition.

Car connection (113):

• Problem: The process of arriving in a house, and leaving it, is fundamental to our daily lives; and very often it involves a car. But the place where cars connect to houses, far from being important and beautiful, is often off to one side and neglected.
• Therefore: Place the parking place for the car and the main entrance, in such a relation to each other, that the shortest route from the parked car into the house, both to the kitchen and to the living rooms, is always through the main entrance. Make the parking place for the car into an actual room which makes a positive and graceful place where the car stands, not just a gap in the terrain.
• In our home: This pattern had a large influence on the design of our entry sequence. This pattern and past experience convinced us that we really didn't want to have multiple main entries into the home. We decided to just have one — there isn't even a door directly inside from the garage. The driveway, garage, and other approaches all funnel into the single (covered) entry. Architecturally, the car connection is not a positive place (i.e., enclosed on multiple sides). however, we are planning on using garden features to give it a feel of enclosure.

Next up in out pattern posts will be a discussion of the patterns that influenced our building envelope.

Our pattern language: Zones

Once upon a time, we spoke of how we narrowed down the 253 patterns in A Pattern Language down to the ~70 that we felt were most relevant to our home. Today we want to go into more detail about those patterns, starting with the "big moves", those patterns that underlie our sense of place.

Our home begins with

House for a small family (76):

• Problem: In a house for a small family, it is the relationship between children and adults which is most critical.
• Therefore: Give the house three distinct parts: a realm for the parents, a realm for the children, and a common area. Conceive these three realms as roughly similar in size, with the commons the largest.^[1]

This overarching pattern leads naturally to three others: Common areas at the heart, Couple's realm, and Children's realm.

Common areas at the heart (129):

• Problem: No social group — whether a family, a work group, or a school group — can survive without constant informal contact among its members.
• Therefore: Create a single common area for every social group. Locate it at the center of gravity of all the spaces the group occupies, and in such a way that the paths which go in and out of the building lie tangent to it.
• In our home: Our open great room acts as the heart of our home. It lies tangent to the main entry (on the right, below) and, less directly, to the back entry (at the bottom of the stairs to the left). We have other shared spaces, but this one is truly the heart of the home.

Common areas at the heart of our main floor

Couple's realm (136):

• Problem: The presence of children in a family often destroys the closeness and the special privacy which a man and wife need together.^[2]
• Therefore: Make a special part of the house distinct from the common areas and all the children's rooms, where the man and woman of the house can be together in private. Give this place a quick path to the children's rooms, but, at all costs, make it a distinctly separate realm.
• In our home: The couple's realm is a distinct space from the rest of the home. It's more than just a bedroom — our realm is meant to be an area where we can comfortably spend time alone together. It is directly across the hall from the children's realm, making that realm distinct but accessible.

Couple's realm and Children's realm upstairs

Children's realm (137):

• Problem: If children do not have space to release a tremendous amount of energy when they need to, they will drive themselves and everybody else in the family up the wall.
• Therefore: Start by placing the small area which will belong entirely to the children — the cluster of their beds. Place it in a separate position toward the back of the house, and in such a way that a continuous play space can made from this cluster to the street, almost like a wide swath inside the house, muddy, toys strewn along the way, touching those family rooms which children need — the bathroom and the kitchen most of all — passing the common area along one side (but leaving quiet sitting areas and the couple's realm entirely separate and inviolate), reaching out to the street, either through its own door or through the entrace room, and ending in an outdoor room, connected to the street, and sheltered, and large enough so that the children can play in it when it rains, yet still be outdoors.
• In our home: This is a detailed pattern. We took what was most important to us. The children's realm is a distinctly separate space. It does have access to the outdoors without cutting through the common space (by the stairs and back door), but, since that path uses the common stair case, the access itself is only weakly part of the children's realm.

These patterns describe the defining zones of our home. In the next post, we'll look at some structures that define the physical layout of our home.

^[1] All of the patterns in have the form: context; problem statement; discussion; conclusion; related patterns. Our pattern posts will have just the problem statement and conclusion; we refer you to the book for the rest

^[2] Yes, this book, published in 1977, is full of heteronormative assumptions. Just try to ignore them.

Soundproofing

Not every home has a media room. This room is dedicated to enjoying video games, shows, movies, and music. It can handle an intimate group — just the two of us — or a larger group — a Rock Band party. One way a media room differs from a family room with a TV is the extra effort put into isolating it from the rest of the house. As much as possible, activity in the media room shouldn't disturb the rest of the house.

Basics of Soundproofing

Let's start with a quick review of sound. Sound travels via vibrations in air and solids (and liquids, but houses generally aren't built from liquids). When a sound wave hits a wall the wall will vibrate, which will cause the air within the wall to vibrate, and transfer sound to the other side of the wall. The sound wave vibrates the studs in the wall, providing a second path to the other side. There are many ways to decrease the amount of sound transferred:

• Decoupling elements: If the drywall on the inside of the room is not directly connected to the outside of the room, then there will be no solid pathways to transfer sound.
• Absorption: Loose material in the empty spaces of the wall help absorb and deaden the sound attempting to travel through the air cavities in the wall.
• Adding mass: Heavier materials require more energy to make them vibrate. By adding mass to the walls, more of the energy from the sound will be absorbed by the walls, and less energy will be available to transfer through the wall.
• Damping: If it is more difficult for the wall to vibrate in the first place (i.e., it doesn't respond as much to the sound waves), then less sound will be transmitted.

This information was summarized from a more in-depth article from the Soundproofing Company.

The Walls

The most important element of a soundproof room is the walls. In the world of soundproofing, there are many wall options and many trade-offs. We chose a solution that is simple and cheap.

The lower part of the walls are formed by the concrete foundation; the added mass of these walls help to reduce sound transmission.

We added soundproofing insulation to the interior walls. The materials and labor for the R-13 insulation was cheap, so we insulated all the interior walls in the house. This will help absorb sound traveling through the air cavities in the walls.


We looked at several wall damping solutions for the media room. A popular solution is Green Glue, a compound put between two layers of drywall to dampen sound. The material is cheap, but it does require a second layer of drywall and extra installation time. Because is is inexpensive and not difficult to install correctly, it is popular in do-it-yourself solutions.

A second option is QuietRock. This is an all-in-one damped panel that is installed in place of drywall. Installation is exactly the same as drywall, but the material costs are more expensive.

Another option was Resilient Channels. These are attached perpendicular to the studs, and drywall is attached only to the channels. This allows the drywall to flex a bit and dampen more of the sound. It also provides decoupling from the studs. The channels are cheap, and installation is not too much more complex than just drywall. Care needs to be taken to prevent the screws connecting the drywall to the channel from touching the studs (this would prevent the flexing and decoupling of the drywall).

We chose channels because of the price and because the installer is familiar with them. Sound isolation clips can be used with some kinds of channel and provide extra isolation, but they add material and labor expenses. We decided channels should be good enough for the level of soundproofing we want. If we want something more, adding Green Glue plus a second layer of drywall is a relatively straightforward addition that we could do later. It wouldn't require removal or remounting of the existing drywall; it is simply a second layer added on top of the existing drywall and channels.

The Details

Walls are the most important part of soundproofing the room, but the details are also important. The mass of a solid core door prevents sound from easily travelling through it. A gasket around the edge of the door provides a strong seal against the frame when closed, and less sound is able to travel through the gaps around the edge of the door.

We avoided can lights because those allow sound to travel through the ceiling. Surface-mount lights allow a solid layer of insulation in the ceiling and nearly unbroken drywall on channels.

The attachment points of the projector mount and screen can negate the advantage of the channels, if screwed into the studs through the drywall. The projector mount is mounted directly to blocks in the ceiling. The drywall will be installed around the mount and a bit of sealant will provide a flexible interface between the drywall and the mount. The screen should be able to attach directly to the drywall without going through to the studs. It is heavier than the projector but spread over a larger area.

Carpet is an easy flooring choice. It provides extra soundproofing, is comfortable, and provides better acoustics. A hard floor would reflect more sound.

Sound travels well through the reflective walls of vents, but fresh air is critical in a tightly-sealed room. We are using a supply and return to the HRV system to provide fresh air into the room and evacuate the stale air. The supply will be tucked into an open portion of the closet, while the return will be in an enclosed portion of the closet. The closet should help muffle the sound that makes it to the vents. They both go to the HRV, which we assume will not transfer too much sound into the other ducts attached to it. Bends in the ducts will also help absorb sound.

Overall, not a lot of changes were needed to provide extra sound isolation in the media room; we mainly had to spend time considering details. From that, we should get a reasonable level of soundproofing without too much extra cost.

Electrical & Wiring Design

One of the areas that requires a lot of design work is wiring: the electrical system and other wiring such as phone, cable, and data connections. It is important to get this right before the walls are sealed up because it is difficult to modify later. It is the system that has the most end-points, will have the greatest effect on day-to-day life, has more flexibility now than it ever will, and has had the least design or input so far.

Outlets near floor in living room. One for data, one for electrical.

Outlets
The electrical system includes the lighting, electrical outlets, and switches. We'll cover lighting separately — it involves a lot more than just wiring.

The electrician spaced the electrical outlets about equally around the walls. Other than a few specific requests, we trusted his judgement and code for the exact placement. On the main floor, our builder had the electrician turn the outlets horizontally and place them close to the floor for a cleaner look. Upstairs in the more functional rooms, outlets are at a standard height and orientation for better accessibility. In a few locations where we know we will have desks or counters, the outlets are just above or below desk height to provide easy access for equipment.

Main breaker panel (rather full)

Other wiring
The rest of the non-lighting electrical wiring is for appliances. Nearly everything in our house is electric, including the HVAC system, water heater, sump pump, dryer, oven, and now the cooktop. We pre-wired for an electric car charger in the garage — this was the biggest cable, up to 100 amps. The oven/microwave combo and cooktop require 50 amps each, the dryer, water heater, and sump pump each use 30 amps, and each of the two exterior heat pump units use 15 amps. This adds up to a large potential load on our electric capacity. Most of these items won't run at full load most of the time, and many will run rarely. A demand-weighted load calculation showed that we should be fine with the standard 200 amp service common in new construction.

Kitchen outlet with phone (blue), ethernet (grey),
and twine for pulling cable through the conduit.

Communications
The area we had the most input on was the communications wiring. We believe cable and phone connections are becoming obsolete, so we only added a few. We have one phone connection in the master dressing room and one in the kitchen (where we're planning a communications center). We added one cable connection in the living room and one in the media room. These should cover most important use cases.

Main ethernet panel with conduit

Our dominant communication technology is digital data streams. This was where we focused most of our attention (and money). Wireless LAN is nice for quick access from anywhere, but it is not as reliable or as fast as ethernet. We have a wired access point in each major area. WLAN or long cables allow access near that endpoint. We specified cat6 cable so it will be usable for as long as possible. Upstairs, we have an endpoint in each of the secondary bedrooms, one in the master dressing room, and one in the laundry/craft room. On the main level, we have one in the kitchen, one in the living room, one in the office, and one in the garage. The closet in the media room will be the center for both media equipment, and our computer connections and servers. All of the ethernet runs from the upper two levels end at a panel in the media closet.

Living room with conduit
for future cabling

Even cat6 ethernet cable will eventually be replaced by something better. To provide future flexibility, conduits run from the media/server closet to locations throughout the house. This is tubing in the walls with a string run through it. In the future, we will be able to pull the latest cable (such as fiber optics) through that tube, allowing us to provide hard-wired access to the main locations in the house.

Crawlspace with several conduit endpoints

Conduit is harder to run and costs more than ethernet cabling, so we limited ourselves to three conduits per level. The upper level has one for each second bedroom, and one in the master dressing room. The main level has one in the kitchen, one in the living room, and one in the office. To make it easier to pull a cable through, the conduits go roughly straight down and end in the crawlspace; one larger conduit connects the crawlspace to the server closet.

Projector mount with conduit and electrical

We have a short conduit within the media room that runs from the media closet up to the middle of the ceiling, where we have a mount point for a projector. This allows us to run a video cable such as HDMI directly from the source equipment up to the projector in a convenient and concealed manner.

Sound
Wireless speakers are good enough for ambient music, so we limited our speaker wiring to the media room.

Two subwoofer coax cables run from the media closet to opposite corners of the room for flexible subwoofer placement. Speaker wiring is run from the media closet out to eight locations in the room: three in the front, three in the back, and two on the sides. Not all of them will be used right away, but we wanted to support whatever future formats might specify. The side speaker wires aren't even ended at an outlet; there is just some extra cable in the wall which could be used in the future. The rear connections end at the floor so that they can be run up a speaker stand. Extra cable was left in the wall higher up to support wall- or ceiling-mounted speakers.

Rear speaker wiring with outlets near the floor
and extra cable above

Security/automation
The final wiring is low voltage wiring for a security system. It also enables the much more interesting possibility of home automation. Door sensors and motion sensors can be triggered for security or automatically turn on lights when someone enters a particular area. Wiring for a security panel can be used to install a touchscreen for central control. Some extra wall switch boxes were installed to support programmed control of lights at several main locations within the house. All the wiring for these systems was run downstairs into the server closet. At our discretion, we can install a panel that connects everything up and provides security, automation, or both.

Green Home Tour

Our house will be participating in the Seattle Green Home Tour this coming weekend! Our in-progress house will be open Saturday and Sunday from 10am-4pm. One or two of the finished houses in the development may be participating, too. We'll be hanging out there for a while each day, and would be happy to give a tour and talk about anything you're interested in.

For address and more information, check out the page about our site.

Heating & Cooling

"Can we have multiple heating zones with this setup?"

What far reaching affects this innocent question had! Our original plans for an HVAC system were fairly typical for a new home in the US: single-zone, central-air, powered by an efficient gas furnace with an attachment point for a future air conditioner coil. You can add zones to variants of this system, but it becomes increasingly complicated (and expensive). Yuval suggested that we look at heat pumps.

What is a heat pump?

A heat pump uses condensation and evaporation of a refrigerant to heat or cool a space. Air source heat pumps use the air as the energy source/sink. It doesn't take much to get a feel for how heat pumps can heat a space:

• Evaporating the refrigerant transfers energy from the air into the refrigerant. The loss of energy leaves the air cooler.
• Condensing the refrigerant transfers energy from the refrigerant into the air. The addition of energy leaves the air warmer.

This may make it seem like heat pumps would require the space where the energy is coming from to be warmer than the space where the energy is going to, but this isn't the case. The heat source only needs to be warm enough to transfer energy to the refrigerant, and the heat sink only needs to be cool enough to accept heat from the refrigerant.

Refrigerators and freezers illustrate this well. They use a small air source heat pump to make cool spaces even cooler by transferring the energy in the fridge into your kitchen (which is, hopefully, much warmer than the fridge or freezer).

For further details, you can read this article and these not-very-good Wikipedia articles: Heat Pumps, Air Source Heat Pumps. And at this point, my facts become an amalgamation of things I have read and things I have learned in conversation — sorry about the lack of citations.

Some trade-offs

Heat pumps are fairly rare in the US today. They are more common internationally (the system we are going with is from Mitsubishi), and the systems have been around for a while. They are common enough, and becoming more popular as their efficiency is recognized, that we shouldn't have problems maintaining our system, but it is a risk.

Heat pumps, at least the ones we are considering, are driven electrically, but run at a much higher efficiency than electric baseboard heat. They are more comparable to an efficient gas furnace, but as the opening question points toward, heat pump systems are easier to configure into zones. Separately-controlled and conditioned zones are often more efficient since you aren't heating the whole house to the same level, but just the area(s) you are currently using. The Mitsubishi system provides a number of other efficiency features, such as providing a variable amount of conditioning (instead of full-on or full-off), and less heat loss in the small, well-insulated refrigerant lines versus standard ductwork.

Heat pumps require refrigerant, and refrigerants are a negative, as far as the environment is concerned. This is partially mitigated by fact that this is a long lifetime, closed system. Mitsubishi also uses refrigerant that has a low environmental impact.

Some heat pump systems, including the one we are using, are reversible — they can transfer energy in  and act as a heater or transfer energy out and act as an air conditioner. Even though we were not planning on installing an air conditioning unit at construction time, using a system which supports both functions results in a simpler, more cost efficient solution.

No ducts! The refrigerant line is hardly larger
than the wiring, and with the wrapping
it's still ~2" in diameter

Heat pumps have one more really big advantage for a green home: they don't require ducts. We are going with a fully ductless setup where the refrigerant lines run directly from the exterior units to the distribution units. This allowed us to open up the main floor by removing the need for some interior soffits. The impact on the roof was much more substantial. Because we don't need to run ducts, our home is now able to support a roof design that provides a significantly higher level of insulation. Since the roof is one of the large energy leakers in a standard home, this will result in a much tighter home. (Sneak preview: this ended up having some unintended consequences in our kitchen.)

Our system

We are going with a Mitsubishi heat pump system. Two external heat pump units will drive six interior distribution units, for a total of six different zones (one per bedroom, two on the main floor, and one downstairs). We decided not to go with programmable thermostats since they are expensive and the units we are buying support a basic level of programmability — a single day/night cycle — that is good enough for us.

Not ugly, but not exactly beautiful

This is one of the units (installed over the door of our dressing room). The units are not huge, but they are not small either. Each unit is about the width of a doorway, and about a foot tall and a foot deep. This is fine in the bedrooms and media room, where we were able to put them in fairly out-of-the-way locations (over doorways). However, we were not able to do this in the open living area of the main floor; we put the distribution unit behind the fireplace — okay, but not ideal.

This was actually a bit of a disappointment. We initially planned to do a system that used small ducts on the main floor to move the air from the distribution units to the open space. This is when green politics got involved. We're going for a Built Green certification on our home — this is a nice-to-have that gives us a verification that our home is green by some external standard and is also good marketing fodder for our builder. To get a Built Greet certification, your heating system must be Energy Star approved. However, Energy Star does not handle configurable systems well.

The exterior hookup.
The installed unit will only be 3' x 3' with a depth of 1'

Both the ducted and ductless variants of the Mitsubishi are Energy Star approved. However, what is not approved is having a single exterior unit drive one ducted interior unit and one non-ducted interior unit. Energy Star approval applies only to the exact system that was evaluated. This makes sense — variations could potentially decrease the efficiency of a system. However, approval is binary, and there is no process for getting small variants approved; the variant has to go through the full approval process, and the cost of that is prohibitive for one-offs or all possible combinations. Okay, rant over =)

Overall, we're happy with the configuration that was installed. We'll provide an update once we've moved in and have experienced how this works in practice!