Do I have enough waste to hot compost?

Sunday, 19 August 2012  |  HOTBIN Composting

Waste converting into compost depends on the temperature (view our composting speed chart). The HOTBIN is focused on helping you achieve hot composting in the 40-60°c range because this is faster and it has other benefits - review ‘hot composting benefits'.

What is the minimum amount of waste each week to achieve hot composting?

Approximately 5Kg (10 litres, one large or 2 small kitchen caddies) per week.

What happens if I have less?

The HOTBIN will only stay hot (between 40-60°c) with regular feeding of the minimum amount of waste. If you have less, you can still use the HOTBIN, you just need to accept it will cool down. It will fall quickly to 40°c, then 30°c then 20°c, and eventually will fall to the ambient temperature - which in the UK is normally 5-20°c depending on the time of year.

Does it matter if it falls below 40°c?

Possibly not! It is going to happen when you go on holiday anyway! It is more a recognition that you will lose the hot composting benefits for a short period and to get back up to temperature will require new waste to be added.

How much food and waste does a typical household produce?

Every household is different in terms of the food and garden waste they produce. In the table below we use a simple scale of small, medium or large to act as a guide.

 

  Small Medium Large
Household size 1-2 people
1 small caddy, about 2.5Kg per week
3-5 People
2 small caddies, about 10 litres (5Kg) of food waste a week)
5-10 people
15-30 litres (large caddy every 2 days)

Garden Size

 

Grass (Lawn)

None or small

 

 

Less than two boxes per week

Medium garden generating cutting, pruning’s and leaves etc). A ‘clean up’ generates a wheel barrow load.

 

2-4 boxes of grass a week

Large garden generating cutting, pruning’s, many autumn leaves, enough tree/woody plants to possibly warrant a shredder so also wood chip. A ‘clean up’ fills 1m3 pallet type bin

More than 4 boxes of grass a week

Current ‘cold’ compost use 1 dalek (plastic cone) does not fill up Need at least 2-3 daleks (plastic cones), always seem full Probably 2-3 large (1m3/each) pallet/NZ-boxes
HOTBIN Units You are unlikely to have enough waste to routinely hot compost. Likely to need 1 HOTBIN Likely to need 2 HOTBINs
Notes

A smaller HOTBIN can be made via a simple DIY project to insert insulated panels inside to reduce the capacity (from 200 litres to 120 litres) and doubling the insulation from 50mm to 100mm.

In rough numbers this allows us to move the minimum waste per day down from 1Kg/day to 0.5Kg per day.

The standard HOTBIN is designed for a medium Household with 3-5 People, and a small to medium garden.

The HOTBIN will cope with 500-1500 litres per year, this equate to having 2 'pallet' frames and or 3 plastic cone daleks.

A large unit is created by adding standard modules. This is more economic and easier to control than producing and using one ‘large’ moulded unit. Do not over scale things - because the HOTBIN composts so much faster, each unit will cope with 500-1500 litres per year.

Even with a large lawn – start with a ‘twin pack’ at first. We tested this with some 'heavy duty' users – 2 HOTBINs will cope with a large grass lawn 5X40L grass boxes composts down (@ 60°c in HOTBIN) to about 1x40 litres in around 7 days).

Very few users spend too much time measuring the weight or volume of waste, but it may help to know that the average 4 person household with a garden generates 250Kg/year of food waste and 300-400Kg/year of green garden waste. This equals approximately 500-1000 litres of waste (or 1m3 which is a full ‘pallet’ compost box, or 3 full daleks).

Tip 1: If you are going to compost all food waste (eg meats, plate scrapings, stale bread as well as the traditional vegetable peelings and tea bags), match your HotBin to your ‘food waste’ rather than your ‘garden waste’ volumes. It is more important to keep your food waste hot composting in winter, than it is having a HOTBIN that is ‘too small’ to cope with your occasional huge garden clean up in summer.

Tip 2: If in you think you will not have enough waste, here are three suggestions to help:

  • Gather more waste in from friends and neighbours
  • Take on a DIY project - it is easy to reduce the HOTBIN from 200L down to 120L as a DIY project,
  • Accept you will be mostly warm composting at 30-40°c, it is still faster many times faster than a cold heap.