Double Garage design - East Sussex

Start your own studio thread here: Goals, plans, layouts, treatment, speakers, questions, queries, comments...
User avatar
John Steel
Active Member
Posts: 29
Joined: Sun, 2019-Sep-22, 09:02
Location: Hastings, East Sussex
Contact:

Double Garage design - East Sussex

#1

Postby John Steel » Sun, 2019-Sep-29, 11:57

This is my first post to the Soundman 2020 - Studio Design Forum. Congratulations on building an amazing forum which I know will become an invaluable resource for countless people around the world. Thank you for sharing your time, skill and considerable experience with us Stuart!
My name is John and I’m developing a design to convert a double garage into a music practise room which can also be used to track instruments including drums and electric guitars. The building is in East Sussex, in the South East of England which has a temperate climate, is situated in a residential area, on a hill, amongst woodland and is detached from the house we live in. The garage is at the edge of a levelled area cut into the side of the hill and the South-Eastern aspect of the building is built into the earth to a height of 131cm (4’4”).
Garage Complete~4.jpg


It sits on a 4” (10cm) concrete base and the internal dimensions are 4.85m x 4.98m (15’11” x 16’04”) - almost square! There is a half-hipped roof which is 4.46m (14’7”) at the highest internal point. The walls consist of a single tier of brick and are buttressed on 3 sides with breeze block columns (or piers), roughly at the centre point of each wall. There is a structural beam which runs from from the North-West wall to the South-East wall at a height of 2.24 M (7’4”). The North-West wall has an outward opening door and window and the South-West aspect has two large openings for the garage doors.
Garage Walls + Joists6.jpg


Although I have learned a great deal of very useful information from Rod Gervais and F. Alton Everest’s excellent books (as well as Soundman 2020) I have a great deal more to learn and I’m fully prepared to do this. Here is a brief outline of what I think I know about achieving my aim - I would be very grateful for any comments, criticism or suggestions if any of you have the (precious) time and inclination.

I have measured the ambient sound level in the area surrounding the garage at 35dB on a windless day and up to 68dB when to wind shakes nearby trees. Passing traffic sometimes elevates the level to 70dB and the occasional light aircraft passing nearby will give a reading of 55dB.
Typically, the loudest instruments I am going to record are drums (I tend to DI bass when recording) which I have measured peaking at up to 116 dB. Local noise regulations are non-specific when it comes to defining an actual level at which sound becomes a nuisance, but as we have neighbours at both sides (6m and 12 metres) I am aiming for a sound transmission reduction of 55dB or greater and while this is ambitious, transmission loss calculations suggests that it’s possible, so I’m optimistic that it can be achieved. I have a budget of £15,000 - £18,000 and intend to undertake as much of the work as I practically can (although I will not attempt any electrical work, fitting the HVAC system or acoustic windows or doors - I would rather pay experienced professionals to do those parts of the job).
I plan to build a single room within a room consisting of two leaves (where possible). The outer leaf will consist of the existing single tier, solid brick wall which will be sealed, up to a height of 221cm, then a combination of 18mm OSB and 12.5mm cement fibre board to meet a ceiling of similar construction, supported by the existing and some additional ceiling chords.
Upper Outer Leaf 2.jpg


I commissioned a report from a structural engineer who advises that with the correct reinforcement to the chords and lowest beam, this is both possible and safe. This can be achieved by forming a ‘flitch beam' (i.e. adding a 10mm steel plate with two staggered rows of bolt holes, sandwiched between another identical beam and held together with M12 bolts).
Flitch_Beam_4.jpg


The existing ceiling chords will be bolted to the joists with M12 bolts.
Chord_Reinforcement_2.jpg


The South-West aspect of the building has two large “up and over” garage doors which will need immobilising, sealing and damping.Then the gaps will be framed with timber, insulated with rock wool and an inner wall of one layer of 12.5mm cement board and one layer of 18mm OSB with green ‘glue’ in between.
garage door gap.jpg


The inner leaf structure will be a conventional stud frame clad with one layer of 18mm OSB and one layer of 12.5mm cement fibre board with green ’glue’ in between to form the inner wall, anchored to the concrete floor with an air gap of at least 30 centimetres between the leaves, which will be loosely filled with rock wool.
Upside-Down Ceiling V.5 Flitch Beam2.jpg


The frame will need to be reinforced on either side of the main beam with two steel 152x89x16mm universal beams in order to support the inner ceiling in a single span. These will need to be pre-drilled in order to attach the connecting timbers.
Upside-Down Ceiling V.5 Flitch Beam.jpg


The inner leaf ceiling will be built using an ‘inside - out” design. The ‘backbone’ will support timber framed modules which will be capped with one layer of 12.5mm cement board and one layer of 18mm OSB with green ‘glue’ in between.
Upside-Down Ceiling 1.jpg

Upside-Down Ceiling 2.jpg


The existing window will be replaced on the outer leaf with a fixed one, glazed with 21mm laminated glass and one on the inner leaf using 12mm glass, conforming as closely as possible to the design in chapter 5 of the second edition of Rod Gervais’s book. The existing door will be removed and two, triple sealed doors (similar to Rod’s “super door”) will be installed with closers.
Window&Doors.jpg


I have spent a lot of time considering the ventilation requirements of the space and my calculations suggest that the the supply ventilation path should consist of a 200mm x 200mm outer louvre fixed to a plenum box and then approximately 75cm of 6”diameter round duct which will be connected (via a 6” sleeve) to an outer leaf silencer box made of 25mm MDF, lined with 25mm of duct liner, with a cross sectional area of 100 in² (645.16 cm²) throughout and incorporating 8 x 90 degree turns. This will penetrate the outer leaf and feed into another run of 6” round duct (approx 100cm) which will connect to a larger, inner leaf silencer, similar in design to the outer leaf silencer, but increased in size to allow a CSA of 144 in² (929 cm²). This will penetrate the inner leaf at head height, adjacent to the mini-split inner unit, via a deflection grill.
Ventilation 1.jpg

Ventilation 4.jpg


The exhaust ventilation path will be similar only in reverse, with the important difference that it will include an inline fan sized to provide the correct airflow pressure and velocity and powerful enough to cope with the static pressure in the ducts and silencers.
Ventilation 2.jpg


I know that the limited space will make acoustic treatment more difficult - I intend to put bass traps in the two windowless corners and attempt to create a variable acoustic using dual purpose absorber / reflectors which can be moved along wall mounted rails or used as free-standing units on the floor, depending on the desired environment.
I’m sure there is much I have overlooked in this and other areas, any thoughts on how to improve my design will be gratefully received and valued.

Thank you for reading this post and best wishes. John.


“While none of the work we do is very important, it is important that we do a great deal of it.”
https://johnsteel.org/

User avatar
Soundman2020
Site Admin
Posts: 889
Joined: Thu, 2019-Sep-19, 22:58
Location: Santiago, Chile
Contact:

Re: Double Garage design - East Sussex

#2

Postby Soundman2020 » Sun, 2019-Sep-29, 16:00

Hi John, and Welcome! :) And also: WOW!. First Jennifer, and now you too! You guys are doing a great job of setting the example for what a first post should be like. :yahoo: I do hope all new members follow your lead.

You have clearly done your homework very well, John, and pretty much everything you said makes sense. Great SketchUp skill too, by the way. :thu:

About the only change I would suggest, and it's minor, is that you put the MDF as the first layer, directly on the studs/joists, then put the fiber-cement board over that, as the outer layer (and with Green Glue, definitely). Fiber-cement boar is somewhat brittle, and can be damaged or cracked easily, so it makes sense to put it on as the last layer, with something more robust and forgiving underneath. There's no acoustic benefit either way: this is just purely practical. It's also a bit easier to do, since the fiber-cement is heavy and difficult to maneuver, so having that MDF base underneath can help with that.

Another thing I would underline, is sealing the brick face interior before you do the inner leaf. You did mention that briefly, but I wanted to highlight the importance of that. Use any good quality masonry sealant. The purpose is simple: brick is porous, implying that air can penetrate into the surface. That messes with the air "spring" in your MSM system, and also robs you of isolation. Masonry sealant (pr even ordinary paint) seals up all of those pores, making the brick air-tight. You'll very likely notice the acoustic difference inside the garage after doing that: it will become more "reverberant", possible developing flutter echos and other things that weren't there before, but that's a GOOD thing! It means the sealant is working, and you'll end up with better isolation.

You didn't mention this specifically in your post, but its also important to seal up every tiny little hole, gap, or crack anywhere in your outer leaf, to ensure that it is completely air-tight. My rule goes like this: "If you see a gap of any type, seal the hell out of it! If you see something that might be a crack but you aren't sure, seal it, just in case. And if you are totally certain that it is NOT a crack, then seal it anyway."

Did I mention that sealing is important?

(Oh, and don't forget to seal stuff...)

I liked the flitch-plate beam idea. Smart move. But you are going to need some help lifting that metal into place! 10mm steel that long and wide, is going to be rather heavy. I would suggest pre-drilling all the holes down on the ground, before you lift it, and use it as the template to also pre-drill the new joist that will go up there. Then once the steel plate is lifted into place next to the existing joists, clamp it very firmly and use it as the template also to drill the existing joist. That way all the holes should like up properly for the bolts. Use large washers on those bolts, on both sides, so that you can tighten the nuts well without them digging into the wood.

Next: Under your new sole plates, spread yet more caulk just before you put the sole plates in place. Run three beads of good-quality caulk: one along the center line of where the sole plate will be, and another two, about an inch (3cm) to each side of the first one. That will give you three good seals already. Then, when you install the first layer of sheathing (your MDF!), put thin shims under the bottom to raise it a few mm off the floor, nail it in place, then pull the shims and seal that gap too. First push backer rod in that gap, all the way to the back, then caulk the remaining gap at the front. Do the same for the fiber-cement board. That ensures that each layer is very well sealed, completely air-tight.

(oh! I think I forgot to tell you that hermetic seals everywhere are important! I should mention that now, I think... :) )

Your plan for supporting the steel beams also looks good, but I would add some extra bracing to the wall framing in that area: normally you would put in noggins every 48" (120cm), both for sheer strength and also for attaching your sheathing), but in the area where the steel will be supported, I'd suggest adding extra noggins ever 16" (40cm), in addition to the ones at 48" (120cm). You want as much structural integrity around those guys as you can get. And the same applies to door framing: extra studs, yes, plus extra noggins.

The existing window will be replaced on the outer leaf with a fixed one, glazed with 21mm laminated glass and one on the inner leaf using 12mm glass, conforming as closely as possible to the design in chapter 5 of the second edition of Rod Gervais’s book.
That reminds me: I have developed a "dynamic component" window in SketchUp, where all of the parameters can be entered and changed as much as you like, then the entire thing updates to take those into account, resizing itself accordingly in all 3 dimensions, then giving you info about itself, such as how heavy it will be, and how well it will isolate. It's not quite ready for public release yet, as there's some things I still need to fix in it, as well as setting reasonable limits (so you can't make a window 1 km wide and 1mm thick, for example), but I do plan to release that eventually. So watch the "downloads" area for that: maybe next month I'll have a bit of time to tweak that.

The existing door will be removed and two, triple sealed doors (similar to Rod’s “super door”) will be installed with closers.
:thu: I'll also post a sequence of images and text from a build that one of my clients did a few years ago, where he took photos at every step of the process for site-building doors exactly like that, from scratch. I designed the door system for him, and he built it up layer by layer... and then go great results when he measured real isolation. In his case, he TEACHES drums in that room, so he often has two drum kits going full bore at the same time, ... with his neighbor's front door just a few meters away. You might find that interesting too, to see how it is done in practice, so you can get ideas for your own doors.

Your HVAC plan also looks good. What flow rates and flow velocities are you aiming for? And did you check that the predicted static pressure will be within the capabilities of the fan you use?

Also, for in-line fans, don't forget that you need to locate it some place where you can have easy access to it for cleaning, maintenance, repairs, replacement, etc. So don't install it between your two leaves, for example! Another option might be to use something like the Fantech units, that are mounted outside your outer-leaf:

Fantech-exterior-exhaust-fan.jpg


Also, for your silencer boxes I came up with a "dual flow" design a few years ago that I'm using for almost all of my new studios these days:

View from above, with top panel removed:
SOUNDMAN2020--HVAC-split-flow-silencer--top.jpg


View from below showing "thru-wall" sleeves and registers.
SOUNDMAN2020--HVAC-split-flow-silencer--bot.jpg


Splitting the airflow like that greatly increases the cross-sectional area of the air flow, improving isolation and also improving static pressure. Instead of being built from one very thick layer of wood, I do it as two thinner layers (but still at least 16mm each), since the thick wood is darn expensive, and also difficult to handle on your own for one person. A 4' x 8' (122 x 244cm) panel of 25mm MDF is HEAVY!!! And dangerous to try to maneuver around your workshop or job site by yourself. So working with two thinner layers makes the job easier and safer.

Feel free to copy the concept, if you wish. I'm working on a SketchUp dynamic component to create such silencer boxes automatically... but it's far from ready. Early stages....

I’m sure there is much I have overlooked in this and other areas, any thoughts on how to improve my design will be gratefully received and valued.

Thank you for reading this post and best wishes. John.
Once again, congrats on your studio, and great work on the first post, and the SketchUp! If you complete the design and to the actual build to the same quality level, your place is gonna be GREAT! :)


- Stuart -



User avatar
John Steel
Active Member
Posts: 29
Joined: Sun, 2019-Sep-22, 09:02
Location: Hastings, East Sussex
Contact:

Re: Double Garage design - East Sussex

#3

Postby John Steel » Mon, 2019-Sep-30, 11:05

Firstly, thank you for the detailed and incredibly helpful response Stuart. This has given me much food for thought and a timely reminder that no matter how well I believe I have things figured out, there’s always room for improvement! The specific advice on caulking and manufacturing the flitch beam are especially useful.


Fibre-cement board is somewhat brittle, and can be damaged or cracked easily, so it makes sense to put it on as the last layer, with something more robust and forgiving underneath


I hadn’t considered this and it’s duly noted.

Another thing I would underline, is sealing the brick face interior before you do the inner leaf. You did mention that briefly, but I wanted to highlight the importance of that. Use any good quality masonry sealant.


Yes, my mistake. I should have mentioned that I intend to use two coats of masonry sealant on the inner surface of the outer leaf.

its also important to seal up every tiny little hole, gap, or crack anywhere in your outer leaf


And there are plenty of gaps to fill, especially round the side door and window where daylight is visible through some of the gaps! As they both need replacing, I’ll have the chance to make they are sealed effectively.

(Oh, and don't forget to seal stuff…)

Roger that!

I liked the flitch-plate beam idea . . . But you are going to need some help lifting that metal into place! 10mm steel that long and wide, is going to be rather heavy.


Very true - and I will also have to raise a great deal of other heavy components and materials into position above the ceiling chords (extra timber, OSB, cement board and of course the silencer boxes which will be very heavy). I am planning to rig up a hoist to assist with this.

. . . in the area where the steel will be supported, I'd suggest adding extra noggins ever 16" (40cm), in addition to the ones at 48" (120cm).


I’m not sure I have understood this correctly - are we talking lateral support to bridge the load to the upright members, something like this?
Extra Noggins.jpg


I'll also post a sequence of images and text from a build that one of my clients did a few years ago, where he took photos at every step of the process for site-building doors


Yes please.

You might find that interesting too, to see how it is done in practice, so you can get ideas for your own doors.


You know it!

What flow rates and flow velocities are you aiming for?


This was the calculation I made in order to justify my ventilation design which now seems rather crude compared to your "dual flow" design.**

The interior size of my new room will be 38.42m3 or 1356.79 ft3. Six changes of air per hour will require an airflow rate of 8140.74 ft3 or 135.67 cu feet per minute. So the minimum cross sectional area of the ducting, while maintaining a velocity of less than 300 feet per min at the register, needs to be no less than 5.42 inches (CSA = CFM/300 or 135.67 divided by 300 = 0.452 ft (5.42 inches). To be safe, let’s call the pipe diameter 6” (152mm).
 So for the supply ventilation path, I think I’ll need an 200mm x 200mm outer louvre (radius of minimum CSA multiplied by itself 76mm x 76mm = 5776mm²  then multiplied by 3.142 = 18148.192mm² and doubled to allow for the 50% ‘free’ area of the louvre design = 36296.384mm². The square root of this last number gives the height & width - both 190.5160mm, let's round that up to 200mm).

 The louvre will be fixed to a plenum box and then approximately 75cm of 6”diameter round duct which will be connected (via a 6” sleeve) to an outer leaf silencer box made of 25mm MDF, lined with 25mm of duct liner, with a CSA of 100 in² (645.16 cm²) throughout and incorporating 8 x 90 degree turns. This will penetrate the outer leaf and feed into another run of 6” round duct (approx 100cm) which will connect to a larger, inner leaf silencer, similar to the outer leaf silencer, but increased in size to allow a CSA of 144 in² (929 cm²). This will penetrate the inner leaf at head height, adjacent to the mini-split inner unit, via a deflection grill.
 The exhaust ventilation path will be similar only in reverse, with the important difference that it will include an inline fan sized to provide the correct airflow pressure and velocity and powerful enough to cope with the static pressure in the ducts and silencers.

Which brings me to the thorny subject of static pressure! 

To calculate this I used the equivalent length method as this seemed the least complicated to comprehend.
  



Silencer box flow calculations using the equivalent duct length method:

10” Equivalent diameter round duct area = 10.9” (small silencers)

12” Equivalent diameter round duct area = 13.1” (large silencers)

Equation for converting a sharp 90 degree bend into an equivalent length of straight duct is:

Duct Diameter x 60 

10” x 60 = 600” or 50’ for each 90 degree turn

x 8 for each silencer = 400 feet of straight duct for each outer leaf silencer
 
and

480 feet of straight duct for each inner leaf silencer.

Using the engineeringtoolbox.com friction or head loss calculator this results in


"Friction Loss (inH2O): 0.0474
Friction Loss (inH2O/100 ft): 0.0119
Air velocity (ft/min): 252
Air velocity (ft/sec): 4.1899999999999995"
(Outer leaf silencer)

and

"Friction Loss (inH2O): 0.00809
Friction Loss (inH2O/100 ft): 0.00809
Air velocity (ft/min): 216
Air velocity (ft/sec): 3.6"
(Inner leaf silencer)

Giving a combined loss for all 4 silencers of 0.11098 (inH2O) or 27.643887046833 pascals and apparently achieving an air velocity of 216 ft/min at the point it enters the inner leaf. 
 Adding in the losses for 2 outer louvres with insect screen  [2x 0.05 in.wg], 2 plenums[2 x 0.01] and 4 metres of additional 6” ducting [0.08 in.wg] (with 2 x 90 degree turns [2 x 0.04] and 4x 45 degree turns [4 x 0.03] ).
 
Total = .71098 in.wg or 177.09 pascals. 





. . . for your silencer boxes I came up with a "dual flow" design a few years ago that I'm using for almost all of my new studios these days


** Back to the drawing board!!

I'm working on a SketchUp dynamic component to create such silencer boxes automatically…


Fantastic! That’ll be a real time saver - once again, I raise my chapeau!

Thanks again Stuart and best wishes, John.


“While none of the work we do is very important, it is important that we do a great deal of it.”
https://johnsteel.org/

User avatar
Soundman2020
Site Admin
Posts: 889
Joined: Thu, 2019-Sep-19, 22:58
Location: Santiago, Chile
Contact:

Re: Double Garage design - East Sussex

#4

Postby Soundman2020 » Tue, 2019-Oct-01, 00:12

John Steel wrote:Firstly, thank you for the detailed and incredibly helpful response Stuart. This has given me much food for thought and a timely reminder that no matter how well I believe I have things figured out, there’s always room for improvement! The specific advice on caulking and manufacturing the flitch beam are especially useful.
:thu:

. . . in the area where the steel will be supported, I'd suggest adding extra noggins ever 16" (40cm), in addition to the ones at 48" (120cm).


I’m not sure I have understood this correctly - are we talking lateral support to bridge the load to the upright members, something like this?
Right! Something like that. Gives it some more lateral stability (in sheer), and makes it a bit stronger overall.

I'll also post a sequence of images and text from a build that one of my clients did a few years ago, where he took photos at every step of the process for site-building doors

Yes please
Done! Site-built studio door pair for high isolation

What flow rates and flow velocities are you aiming for?


This was the calculation I made in order to justify my ventilation design ...
Your math looks good to me. But 0.71 in.wg is pretty high. You might need a booster fan. Using the dual-flow type registers would help a bit with that, since you have some of your air paths in parallel, not in series, so static pressure is lower through that part.

. . . for your silencer boxes I came up with a "dual flow" design a few years ago that I'm using for almost all of my new studios these days


** Back to the drawing board!!
Feel free to copy that concept! In a few weeks, when I have time, I'll update the dynamic component for that, and perhaps release it publicly...

Thanks again Stuart and best wishes, John
Congrats on the math you did for the HVAC! That's a really good example for others to follow. First-time studio builders often don't realize how important this is! But you certainly did. :thu:


- Stuart -



User avatar
endorka
Senior Member
Posts: 666
Joined: Mon, 2019-Sep-23, 06:36
Location: Scotland
Contact:

Re: Double Garage design - East Sussex

#5

Postby endorka » Tue, 2019-Oct-01, 02:23

Soundman2020 wrote:Congrats on the math you did for the HVAC! That's a really good example for others to follow. First-time studio builders often don't realize how important this is! But you certainly did. :thu:


I concur. I'm just applying your calculations to my place. It's pretty much there, although I still haven't figured out how you derived the CSA sizes for your silencer boxes :-)

Cheers,
Jennifer



User avatar
John Steel
Active Member
Posts: 29
Joined: Sun, 2019-Sep-22, 09:02
Location: Hastings, East Sussex
Contact:

Re: Double Garage design - East Sussex

#6

Postby John Steel » Tue, 2019-Oct-01, 08:04

Thanks for your review of my ramble and suggestions Stuart - I have PM'ed you as I think I will need some help informed by experience in order to tweak the design. Also greatly obliged for the build diary of the triple seal doors - they're magnificent and have given me something to aim for.
Hello & howdo' Jennifer? I have been reading your thread and you have a great studio which clearly produces fantastic results in the real world already. I really like how much daylight you have in there; in my experience that makes a huge difference to how pleasant a space is to work in.
Regarding the CSA of the silencer boxes, I figured out the dimensions of mine like this (I would add that I’m not any kind of expert in fluid engineering!!).

I calculated the volume of the room and know that this amount of air needs to be changed at least six times an hour:

CFM (cubic feet per minute) = V(olume) x 6, then divided by 60 (minutes)

We know that air velocity should be less than <300 feet per min at the point it reaches the register on the inner leaf, so the CSA of the ducting can be calculated like this:

CSA = CFM/300

(NB this is the very minimum value it can be, so I rounded up.)

Once you know the CSA of the ducting, you have to allow at least a doubling of CSA inside the outer leaf silencer and ideally a further increase in CSA inside the inner leaf silencer. What this achieves is a slowing of the air into the silencers which reduces turbulence and therefore noise. At least that’s my understanding.
Best wishes, John.


“While none of the work we do is very important, it is important that we do a great deal of it.”
https://johnsteel.org/

User avatar
endorka
Senior Member
Posts: 666
Joined: Mon, 2019-Sep-23, 06:36
Location: Scotland
Contact:

Re: Double Garage design - East Sussex

#7

Postby endorka » Tue, 2019-Oct-01, 09:42

John Steel wrote: Hello & howdo' Jennifer? I have been reading your thread and you have a great studio which clearly produces fantastic results in the real world already. I really like how much daylight you have in there; in my experience that makes a huge difference to how pleasant a space is to work in.


Cheers John, musicians really do enjoy the daylight, and I think the perception of light and airiness helps offset the dry acoustic somewhat. I'm looking forward to seeing your build develop, it is quite an undertaking!

Once you know the CSA of the ducting, you have to allow at least a doubling of CSA inside the outer leaf silencer and ideally a further increase in CSA inside the inner leaf silencer. What this achieves is a slowing of the air into the silencers which reduces turbulence and therefore noise. At least that’s my understanding.
Best wishes, John.


Understood - it was this part I wasn't getting, the different sizes for the leaves. :thu:

I'd be very interested to know if you have found an appropriate inline fan for your studio yet? :-)

Cheers!
Jennifer



User avatar
John Steel
Active Member
Posts: 29
Joined: Sun, 2019-Sep-22, 09:02
Location: Hastings, East Sussex
Contact:

Re: Double Garage design - East Sussex

#8

Postby John Steel » Wed, 2019-Oct-02, 08:48

I'd be very interested to know if you have found an appropriate inline fan for your studio yet?


I had thought an inline fan like this would do the trick.
https://www.ductstore.co.uk/acatalog/info-TDSIL-500-150-160-T.html

- as it seemed to be the correct spec to deal with the airflow & static pressure. However, I'm in the process of largely re-drawing the HVAC system in the light of Stuart's last post, so I'll let you know when I know! ATB John.


“While none of the work we do is very important, it is important that we do a great deal of it.”
https://johnsteel.org/

User avatar
endorka
Senior Member
Posts: 666
Joined: Mon, 2019-Sep-23, 06:36
Location: Scotland
Contact:

Re: Double Garage design - East Sussex

#9

Postby endorka » Wed, 2019-Oct-02, 12:35

That range of fans look ideal, certainly the datasheet gives a good picture of their performance. Nice to see them include noise output in octave bands for inlet, outlet and radiated. I've attached it to this post, hopefully that's ok to do here.

Is it acceptable to oversize the fan (in terms of duct diameter) to achieve greater flow at a given static pressure at a lower noise level I wonder?

Also interesting that the models without the timer run on can be set to slow or fast speeds, but the ones with timer only do fast.

Cheers,
Jennifer
Attachments
TD SILENT Range Inline Fans.pdf
(1.47 MiB) Downloaded 1350 times
TD SILENT Range Inline Fans.pdf
(1.47 MiB) Downloaded 1350 times



User avatar
John Steel
Active Member
Posts: 29
Joined: Sun, 2019-Sep-22, 09:02
Location: Hastings, East Sussex
Contact:

Re: Double Garage design - East Sussex

#10

Postby John Steel » Wed, 2019-Oct-02, 19:36

Hello again,

Is it acceptable to oversize the fan (in terms of duct diameter) to achieve greater flow at a given static pressure at a lower noise level I wonder?


Good question (to which I don't have a Y/N answer)! I seem to remember reading somewhere that HVAC systems should not be over engineered for a variety of reasons. I'm not an expert in this field (far from it) but I believe that the primary reason for this is that they only work efficiently when they are 'right sized' (appropriately specified) to the space and prevailing conditions. What you definitely don't want is to be continuously adjusting it to hit a 'sweet spot' or (at the other extreme) running it flat out to keep up.
Also interesting that the models without the timer run on can be set to slow or fast speeds, but the ones with timer only do fast.


Yes, that struck me as strange! I suppose they're intended for industrial applications in general rather than studio design in particular.
The other thing that I think it's worth mentioning is considering the amount of stuff (instruments, amps, keyboards, racks, cases, speakers, mixing console, furniture etc) that is in the room as this reduces the volume of air you need to move. I have heard this difference quantified as 10 - 15% for a small studio - so there's that (as if there wasn't already enough).
ATB John.


“While none of the work we do is very important, it is important that we do a great deal of it.”
https://johnsteel.org/

User avatar
Soundman2020
Site Admin
Posts: 889
Joined: Thu, 2019-Sep-19, 22:58
Location: Santiago, Chile
Contact:

Re: Double Garage design - East Sussex

#11

Postby Soundman2020 » Mon, 2019-Oct-21, 20:55

endorka wrote:Is it acceptable to oversize the fan (in terms of duct diameter) to achieve greater flow at a given static pressure at a lower noise level I wonder?
To a certain extent, yes, but you don't want to over-do it, as John mentioned. And if you oversize the fan, in the sense of larger diameter, then you need to increase all the duct sizes to match that: any time you have a change in cross sectional area that also implies a change in pressures and velocities, so you have to be careful with that. Thus, it's not a good idea to have a 10" fan blowing into an 8" duct, for example. Increasing area is fine, but reducing it is potentially an issue. Smaller cross section implies higher air velocity, thus more turbulence, more noise, more friction, etc. (friction along the walls increases with the SQUARE of the air velocity, so even modest increases in velocity can produce large increases in that).

The general rule in HVAC is to "right size" things, with a little extra margin for unforeseen stuff, but without going crazy.

- Stuart -



User avatar
John Steel
Active Member
Posts: 29
Joined: Sun, 2019-Sep-22, 09:02
Location: Hastings, East Sussex
Contact:

Re: Double Garage design - East Sussex

#12

Postby John Steel » Wed, 2020-Jan-08, 12:45

Hello again & happy New Year to all,
I've been working on re-designing the HVAC system for my studio design after some very helpful input from Stuart. This includes eliminating wasted space in the wall cavities between the inner and outer leaves and repositioning the inner leaf silencers to the ceiling so that, on the input side they guide airflow directly into the AC unit.
New Silencers-4.jpg


The inner silencers will now replace eight 'inside out' ceiling modules (four on each side of the room) and while this lowers the ceiling height in the middle of the room, it allows for the inner leaf walls to be moved out slightly which will increase the floor area.
New Silencers-7 .jpg

New Silencers-9.jpg

Stuart also suggested using 'inside out' modular panels for the inner leaf walls where possible as this will also increase the volume of the room and, if I understand this correctly, building the middle leaf ceiling below the existing rafters instead of above them to avoid the difficulty of building around the existing bracing.
Inside-out wall module.jpg

Middle-leaf ceiling 1.jpg

Middle-leaf ceiling 2.jpg


It think the design is getting close to the point where I can actually start building - unless of course I'm missing something (or indeed several things)!


“While none of the work we do is very important, it is important that we do a great deal of it.”
https://johnsteel.org/

User avatar
John Steel
Active Member
Posts: 29
Joined: Sun, 2019-Sep-22, 09:02
Location: Hastings, East Sussex
Contact:

Double Garage design - East Sussex

#13

Postby John Steel » Fri, 2020-May-01, 07:49

I hope everyone is well, safe and not finding social distancing too much of a burden. I have been trying to offset the frustrations of various delays by re-examining my design; I think I finally understand how to make the ductless mini-split system work as well as it can in my room and I’ve also been writing a blog about my experience so far. It’s called “Building a studio - How hard can it be?” and is a work in progress (so may contain errors & omissions!!).

The penny finally dropped for me regarding HVAC after I read Greg's excellent post outlining the difference between forced air systems and ductless mini – split systems and the proportionate difference in airflow. So I re worked the numbers and re drew the silencers armed with the knowledge that they don’t have to be the monolithic items I’d planned to handle 70% more air volume than I really need. So far so good!
HVAC UD 04-20-(a).jpg

HVAC UD 04-20-(c).jpg

HVAC UD 04-20-(d).jpg

HVAC UD 04-20-(i).jpg

HVAC UD 04-20-(j).jpg

It’s funny how long it takes for the blindingly obvious to occur (to me anyway) but the other big problem I faced with my first two designs was finding space for the inner leaf silencers. I intended to replace some of the ‘inside out’ ceiling modules I planned with the boxes but that would have meant lowering the (already low-ish) ceiling height in those parts of the room. Then it occurred to me that by raising the two joists nearest each gable by 20cm I could make plenty of space for them and simply contour the outer leaf around them.
HVAC UD 04-20-(0).jpg

HVAC UD 04-20-(n).jpg

Maybe not the most productive use of lockdown time, but it feels like progress to me at least!


“While none of the work we do is very important, it is important that we do a great deal of it.”
https://johnsteel.org/

User avatar
Starlight
Full Member
Posts: 459
Joined: Wed, 2019-Sep-25, 12:52
Location: Slovakia, Europe
Contact:

Double Garage design - East Sussex

#14

Postby Starlight » Thu, 2020-May-14, 09:51

John Steel wrote:Source of the postIt’s funny how long it takes for the blindingly obvious to occur ...

I too find there are times when building a studio can feel like a Chinese puzzle (or a Rubik cube) - there must be a way but it takes a fair bit of faffing around to find it. Well done on making use of your time, Tom. Even if it doesn't feel productive now your new understanding will prove to be really useful in the days ahead.



User avatar
John Steel
Active Member
Posts: 29
Joined: Sun, 2019-Sep-22, 09:02
Location: Hastings, East Sussex
Contact:

Double Garage design - East Sussex

#15

Postby John Steel » Sat, 2020-May-16, 07:03

Thanks for the encouragement Starlight (a little goes a long way)! I have managed to obtain the materials I need to get going on my outer leaf and I'm making steady progress and I'll update my build thread as soon as I find time. How's your studio progressing, it seemed very close to complete last time I checked? ATB John.


“While none of the work we do is very important, it is important that we do a great deal of it.”
https://johnsteel.org/


  • Similar Topics
    Statistics
    Last post

Who is online

Users browsing this forum: Google [Bot] and 26 guests