There are two possible causes of low efficiency. A poor mash, and/or a poor sparge.
The most likely causes of a poor mash are (in no particular order):
Poor grain crush
Inadequate mixing at dough in
Poor temperature control
Insufficient mash time
Excessively thick (< 1 qt water/lb) or thin (> 2 qt water/lb) mash
Unsuitable water. (Insufficient calcium, or wrong mash pH)
Wrong mashing technique. (Some malts require multi-step mashes)
Inaccurate hydrometer
The most likely causes of a poor sparge are (again in no particular order):
Poor temperature control
Insufficient sparge water
Inadequate mixing of the sparge water with the mash before draining
Sparging too fast
Unbalanced sparge volumes
Unsuitable equipment
Inaccurate hydrometer
Fortunately, many of these potential problems can be identified and corrected.
Does the thermometer read correctly in iced water (32F)
Does the thermometer read correctly in boiling water (212F at seal level - see
http://www.apo.nmsu.edu/site/directory/kloomis/bpH2O.html for altitude corrections)
Does the hydrometer read 1.000 in 60F water (tap water should be OK for this test)
The crushed grain should have a small amount of flour, and none of the grains should be completely intact
After dough in, the mash should have a similar consistency to porridge with no dry grains or lumps.
If you mash for 60 minutes, that should be plenty. If less, you may want to try a starch conversion test, or increasing the mash time.
A simple single infusion mash should be OK for any normal IPA recipe.
Sparging too fast, and unsuitable equipment usually relate to fly sparging, and can be ignored for batch sparging.
When sparging, you want to keep the temp of the grains in the range of 165F to 170F. Many people do a mash out by adding boiling water to raise the temperature before starting the sparge. Others use extra hot sparge water for the first sparge.
If sparging with more than one batch, try to keep the batch volumes approximately equal.
If you are following a reputable recipe, it is unlikely that you will have insufficient sparge water.
When batch sparging, add the sparge water and stir really well for a couple of minutes. Then recirculate about 1/2g (until the runnings are clear) before draining into the kettle.
Determining the suitability of the water is really beyond the means of most homebrewers, but you could get a water report, and test the pH of the mash.
The best way to determine if the problem is in the mash or the sparge, is to test the gravity of the final running. A gravity of 1.010 to 1.025 indicates a good sparge. A gravity much above 1.025 would indicate that you are leaving a lot of sugars behind.
Hope this helps.
-a.
Edit >>
There were only about 2 replies when I started typing this. I must learn to type faster, or stop SWMBO from interrupting me.
I'll get another thermometer just to compare.
