Kitchen Downlight Advice Needed (Spacing & Brightness)

[Mav3000]

Hi, I have a kitchen / dining room 3.5m wide by 5m long, with the kitchen / dining room split 2.5m each.

I plan to have installed downlights and have always thought that 8 would be enough, in a grid 2 x 4 evenly spaced across the ceiling. I am looking to buy 8x20w low voltage GU10 bulbs, with 36 degree spread of light from each bulb.

Is this enough to properly illuminate a room this size? Do I need more lights, or brighter bulbs?

I am conscious that 8x20w equals 160w of light, but am worried the spread isn't enough to properly illuminate the edges of the room.

Any advice would be appreciated.

Mav3000

 

[LiamPope]

You know those plastic glow in the dark stars and moons that you might find on kid's bedroom ceilings? They would better illuminate your kitchen/diner than your current proposal .

I have 5 50W downlights in a small 2x2.5m bathroom and that is about enough. The whole room is tiled so the light bounces around enough to create quite a uniform diffuse lighting throughout the space (unless you look up). 8 36degree 20W downlights in a room that size pointed at the floor will result in 8 dim pools of light on the floor and pitch black walls and work surfaces. Don't be fooled by having a similar wattage figure to whatever you're replacing with these downlights, as the illumination provided by downlights is totally different. I wouldn't be surprised to find a good kW or more of downlighting required to reasonably illuminate a room this size.

Liam

 

[mikhailfaradayski]

Hi Mav,

I had a similar situation last year, similar sized kitchen, customer wanted 2x4 grid of d/l's, 230V 50W. Due to the worktops around the edge of the kitchen, i tried to advise that they should have undercabinet lights or 3x4 grid to carry light closer to the worktop edge. Reason was, that although the light level from the D/l's gave sufficient general light (considering floor level), when working at the worktop, anything you do would be done in your own shadow.
Customer declined this suggestion mentioning additional costs.
A couple of weeks after the job was completed, customer called me to ask if i could fit under-cab lights as they couldn't see much when cooking (well, there's a surprise, eh? ), oh, and could i still give them switching from three points, the same as their d/l's. They weren't too impressed when the price was now about triple by comparison to original price and only gave local switching. Hay-ho there ya go

 

[Mav3000]

Thanks for the quick reply Liam. Our ceilings are 2.3m high. We recently had 4 20w GU10s put into our bathroom which lights it up nicely. The bathroom is 2x2m pretty much.

Would 8x50w in the same grid layout be sufficient? I can always change the bulbs if they aren't bright enough, but obviously can't change the layout of the lighting once the holes have been drilled.

My current layout idea is to divide the room into thirds horisontally across the 3.5m width, then into 5ths down the 5m length of the room, to space the lights out evenly. this makes each light approx 1m from the wall, and 1m from any other downlight.

 

[aptsys]

I would recommend these over halogen downlights: http://www.screwfix.com/prods/51213...LT-E-Fixed-White-Indoor-Low-Energy-Downlights

Although a more expensive than halogen fittings, they give excellent spread of light, and no issues with lamp life.

 

[LiamPope]

I don't really have the experience to say, but I think it likely 8 50W downlights would also be unsatisfactory. As mikhail says, you wont be able to see you're doing at the worktops unless you also install additional lighting.

Personally, I have two of these in my kitchen. Lights up like a laboratory, as a functional room ought to imho .

Liam

 

[ColJack]

Thanks for the quick reply Liam. Our ceilings are 2.3m high. We recently had 4 20w GU10s put into our bathroom which lights it up nicely. The bathroom is 2x2m pretty much.

so figuring about 500mm from a wall, that's one every 1m on a grid?
is that a useable light or a nice relaxing in the bath kind of light?


in the kitchen area, you want the lights about 500-650 from the wall or you will be working in your own shadow on the work surface..

in the dining area you'll need a center row too for iluminating the table..

so I recon 3 columns across the 3500 width.. at 600 from the wall for the 2 outside ones and the center one at 1750 from the wall.

6 rows spaced at 750 apart starting with the first row at 500 from the wall at the kitchen end..

that makes 18 by my count?
I'd recomend using more 20/35W lamps and switch them in groups rather than fewer 50W lamps and try to dim them later..

 

[Mav3000]

Our bathroom has 4 lights in a square - three 20w GU10s and a 4th light above the shower which is a 35w bulb / shower fan. The light is bright (its a lightly coloured bathroom with white suite) but is not too bright. We have thought about upgrading to 35w in the future, but don't feel the need to.

In regards to the kitchen, I agree about the worktop lighting and like the idea of moving the grid such that it is nearer the wall thus over the worktops more.

It is our intention to have a triple switch - one switch for the group of downlights in the dining area, one for the downlights in the kitchen area, and one for the kitchen cabinet downlights. None on dimmers.

A grid of 18 lights sounds like a lot of energy, but I like the look of the low voltage ones (thanks for the link aptsys) as an energy saving solution. I am hesitant to look at mains powered solutions due to bulb life.

PS, we are looking to put 50mm polystyrene boards up between the joists as a small measure to reduce the 'sounds' from the bathroom directly above the kitchen area. Will standard downlights be ok if we cut a hole in the polystyrene boarding around the lights in regards to ventilation? I was looking at the downwards reflecting GU10 bulbs to disperse the heat into the room, and not into the ceiling void.

Thanks for all the help so far,

Mav3000

 

[Mav3000]

ColJack,

I've just plotted your spacing idea onto my room diagram and it looks excellent. In the kitchen area, we plan to have some high-level cabinets across the bottom-right half of the 3.5m wall and on the bottom-right-hand-side wall (halfway up the 5m length). These may impede the layout of the lights if they are only 500mm from the walls. In this instance I may need to move them slightly further inwards off the wall, or have brightly illuminated cupbard doors.

18 x 20w means 360watts to power the entire kitchen / diner. Doesn't sound too bad for the time they'd be on. I think we'd switch the kitchen lights off while dining in the dining area however in order to hide the washing up.

 

[ColJack]

you seem to be confusing low voltage and low energy..

what you call low voltage is 12V..
low energy are still 230V..
the ones linked to are low energy..

low voltage doesn't save any energy.. 50W is still 50W whether it's 12V or 230V..

polystyrene insulation anywhere near the lights will melt.. and it still gets hot in the void even with reflector bulbs..
polystyrene also doesn't like PVC cable.. it tends to eat into it....

you want at least 9 lights in the kitchen, 3 columns across the 3500 width, and 3 rows across the 2500 length of the kitchen section.. ( 500, 1250 and 2000 from the end wall.. )

in the dining section you could probably get away with 2 columns at 1250 from each wall ( giving 1000 between in the middle ) and 3 rows.. so 6 in the dining area

 

[flameport]

PS, we are looking to put 50mm polystyrene boards up between the joists as a small measure to reduce the 'sounds' from the bathroom directly above the kitchen area. Will standard downlights be ok if we cut a hole in the polystyrene boarding around the lights in regards to ventilation?

Halogen lamps + polystyrene = fire. Or at best, a revolting melted mess. It also damages PVC cables.

You would need rather large holes, at least 12 inches across to ensure adequate spacing from the lights. Halogen lamps get very hot, regardless of the type.

Even without big holes in it, expanded polystyrene will be useless at reducing noise.

 

[ColJack]

most upper cabinets are only about 300-350 deep.. and the counter is 600 deep.. so it's a ballancing act to get the lights to illuminate the counter without casting shadows from the uppers or the person stood at the counter..

as you mention UC lights then that's not such a problem as the UC lights will light the counters..

 

[Mav3000]

Wow thanks for the advice on the polystyrene insultation. I was getting it delivered this weekend but will cancel that from the order now.

ColJack, apologies for confusing energy saving and low voltage options. My thoughts were between either 20w LV lights or energy saving 230v lights in regards to electric usage.

I like the idea of 18 lights - 9 in the kitchen and 9 in the dining area, as it would have symmetry and balance across the ceiling.

Any good recommendations for something to absorb sound in the ceiling void whist sitting near the downlights and not burning down the house? or is the void best left empty to help disperse the heat? We will be re-fitting 12.5m plasterboard to the ceiling, but previous experience lets me know this doesn't absorb enough sound.

PS, any thoughts on LED downlights? is the light not enough, and is it too 'cold'?

 

[flameport]

To reduce noise through a wall or ceiling, you need mass, and lots of it. You also need to ensure the ceiling and the floor above is properly sealed so that there are no gaps for sound to pass through (of course, this rules out downlighters completely unless you plan to construct sealed plasterboard boxes above each light fitting.)

Some options:
Rather than fit the plasterboard directly to the ceiling, there are metal support bars available which fix to battens, and the plasterboard fixes to the metal bars. They are slightly flexible so that vibrations from the floor above are not directly transferred to the ceiling below.
One example: http://www.sigexpress.co.uk/Speedline-Metal/Speedline-Resilient-Bar.htm
Higher density plasterboard can also be obtained, or multiple layers can be used.

Accoustic wool or other insulation can be put in the ceiling space. This won't do much to stop sound going through it but will stop it echoing between the ceiling and floor above.

You could remove the floor above completely, and fit 1x1 battens to each side of the joists halfway between the floor and ceiling. Then glue long rubber strips to the top of the battens, and cut some 25mm thick MDF sheets to rest on top of the battens/rubber strips. There should be a 5mm gap between the MDF and the joists. Fill the gap with silicone. It is important that the MDF does not touch the joists or battens directly.
The gap at the ends between the MDF and the wall must also be sealed.

To go further, a 1 inch layer of dry sand could be put on top of the MDF. (use the cleaned, dried and sterilised type intended for children to play in, otherwise it could go mouldy or worse).

When the floor is replaced, make sure there are no gaps or cracks anywhere.

Of course all of this will increase the weight loading significantly, so it would be advisable to check you are not overloading the structure.

 

[LiamPope]

Wow thanks for the advice on the polystyrene insultation. I was getting it delivered this weekend but will cancel that from the order now.

Doubly good job you're cancelling it - as well as being a fire hazard, polystyrene insulation would have made a useless acoustic insulator, too! Probably no better than leaving the air cavity empty. You really need pure mass to attenuate sound, though layer boundaries and convoluted paths can help, so stuff like dense open cell foams, or if you're really pushed rockwool, and creating sandwich layer structures also will help. Best would be to build up extra layers of plasterboard (you can get an extra dense plasterboard called soundstop board if I recall), or ply/mdf etc, and fill the joist cavities with rubber foam or rockwool.

Of course all this work is damaged by punching downlight holes in your ceiling!! You can get acoustic rated downlights, though these are more concerned with meeting building regs bare minimums than providing decent sound insulation. Better if they're not there at all!

Liam

EDIT: Or what he said ^^^! Though getting into isolation/floating floors etc etc, whilst good for a band practice room, may be overkill for a toilet