The only way to get a low alcohol wine is to water the grape juice down, but beer recipes can be adjusted to compensate for a more meager alcohol content. If you want an IPA with half of the standard alcohol content it is not as simple as cutting in half each malt and hop addition. I brewed a ~2% ABV Micro-IPA from the second runnings of a hoppy wheat beer a few months ago, and while it had the aromatic hop character I wanted it was severely lacking in malt backbone. Reducing the amount of malt can also result in a thin body, and the lower sweetness can lead to an unbalanced flavor. A few ideas to combat those pitfalls:
Boosting Perceived Body:
1. Add more crystal/dextrin malt, which will add sweetness and mouthfeel.
2. Add unmalted grains (especially oats and rye) for their beta-glucans, which add body without sweetness, but can also contribute haze.
3. Raise the saccharification rest temperature, a good choice to avoid the sweetness of crystal malts.
4. Use a less attenuative yeast strain, English strains are especially well suited.
5. Use a strain that produce a high amount of glycerin/glycerol, saison strains tend to excel at this.
6. Lower carbonation, I find high carbonation makes light beers taste seltzer-like (although higher carbonation can help excessively thin beers, like gueuze).
Enhancing Malt Flavor:
1. Use a more flavorful base malt like Maris Otter, Vienna, Munich, or dark wheat.
2. Raise the percentage of specialty malts, especially toasty malts like Victory, biscuit, and melanoidin.
3. Eliminate adjuncts like corn/table sugar, and corn which dilute malt flavor.
4. Conduct a no-sparge mash to increase color/flavor, and minimize tannin extraction.
Maintaining Balance:
1. For a hoppy beer reduce the IBUs proportionally to the expected residual extract (I think this is a better way to think about balance than the classic BU:GU ratio).
2. Do not trim late boil additions as much to maintain a solid hop aroma.
3. For dark beers consider increasing the percentage, but cold steeping your roasted grains to reduce harshness.
4. Use a more expressive yeast because the lower gravity will result in a cleaner fermentation profile.
5. Account for serving the beer fresher than you would a strong beer (e.g., use a highly flocculent yeast).
These are certainly not all things that should be done concurrently for one batch of session beer, but it is a good idea to pick the ones that make sense for the type of beer you are brewing. For this batch I switched out most of the bland American pale I would usually use in an IPA for toastier Vienna malt. I also opted for a hotter mash and no-sparged to boost the body and malt flavor. I selected a low attenuating English yeast to replace the default Chico strain, to add both body and additional flavor.
Session Vienna "IPA"
Recipe Specifics
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Batch Size (Gal): 5.25
Total Grain (Lbs): 10.00
Anticipated OG: 1.038
Anticipated SRM: 5.6
Anticipated IBU: 37.5
Brewhouse Efficiency: 54 %
Wort Boil Time: 60 Minutes
Grain
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72.5% - 7.25 lbs. German Vienna Malt
22.5% - 2.25 lbs. American Pale Malt
5.0% - 0.50 lbs. CaraVienna
Hops
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0.50 oz. Simcoe (Pellet, 11.00% AA) @ 15 min.
0.25 oz. Columbus (Pellet, 11.00% AA) @ 15 min.
0.75 oz. Amarillo (Pellet, 10.00% AA) @ 10 min.
0.75 oz. Simcoe Pellet (Pellet, 11.00% AA) @ 5 min.
1.50 oz. Amarillo (Pellet, 10.00% AA) @ 0 min.
1.50 oz. Columbus (Pellet, 11.00% AA) @ 0 min.
1.50 oz. Simcoe (Pellet, 11.00% AA) @ 0 min.
1.25 oz. Amarillo (Whole, 11.00% AA) @ Dry Hop
1.25 oz. Columbus (Whole, 11.00% AA) @ Dry Hop
1.25 oz. Simcoe (Whole, 14.00% AA) @ Dry Hop
Extras
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0.50 Unit Whirlfloc @ 12 min.
0.40 Tsp Yeast Nutrient @ 12 min.
Yeast
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White Labs WLP037 Yorkshire Square Ale
Water Profile
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Profile: Washington DC cut 50% with distilled, plus 2 g CaCl and 1 g gypsum
Mash Schedule
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Sacch Rest 40 min @ 153
Notes
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1/10/12 Starter made with .75 L, first time using the stir plate.
Cut with 50% gallons of distilled water to lower carbonate. Added 2 g of CaCl to the mash since I was short on gypsum.
Valley Malting Pale.
No Sparge, filled up the 5 gallon mash tun to the brim. Collected 3.5 gallons of first runnings @ 1.060. Diluted with 3.25 gallons of the diluted DC Tap water and 1 g of gypsum.
Added 1 oz of each hop and let sit for 25 min, then chilled with the addition of an additional .5 oz of each.
Chilled to 68 F, strained, and pitched the slightly decanted starter (finished quickly and flocc'd hard). Left at 64 F ambient to ferment
Good fermentation by 12 hours. Gave periodic twists to help with the high flocculating yeast.
1/20/12 Racked to a double purged keg with the bagged dry hops. Pretty full fill on the keg. Hit with ~30 PSI and shook twice to get a jump on the carbonation. Left in the basement at ~45 F to dry hop and drop clear. Down to 1.010, tasted a bit more bitter than I expected, but cold and time should help that.
2/16/12 Couldn't be happier with the way this one turned out. Similar balance to a West Coast IPA, but at half the alcohol.