Summary

10/11/2006

Twenty-three households in single family homes around Greater Cincinnati and Greater Columbus Ohio volunteered to participate in my 2005 survey. This presentation includes both text and tables summarizing the results. Table 1 (below) shows summed raw data and responses, plus calculated performance values. Energy from all conventional sources was converted to comparable BTU content, then subjected to parallel calculations and comparisons. For the first time in my surveys, daily average CO2 emissions demand per person is shown, as well as water purchased per person per day. Lowest values in each category are shown in green cells, highest values in pink cells. Table 2 (further below) shows energy efficiency (EE) and alternate energy (AE) features reported in "EE-AE Measures" column. Some commentary occurs prior to the tables, but further commentary is below the tables.

Ideally, one might think that a "most efficient" household would have lowest energy cost overall, lowest energy cost and/or usage per square foot (sf) of conditioned space, and lowest energy cost and/or usage per person. One might also presume that if energy usage is lowest, so is CO2 emissions demand and/or water use. Unfortunately, none of these assumptions would be totally true most of the time, but certain households do tend to emerge as seeming "winners" across several categories. More on this after some commentary...

Two households (lines 9 and 11) using natural gas (still cheap per Btu, even after its record high prices in late 2005) achieved lowest operation cost of 40 cents per square foot per year. Four households (lines 23, 32, 33, 34) in so-called "all-electric" homes achieved almost-as-low operation cost per sf (below 45 cents), even though only one had a "geothermal" HVAC system, commonly claimed as "currently most efficient" among electric heating and cooling systems. One older less insulated home (line 14) using high-priced LP for heating energy paid $2.30 per sf, almost 6 times higher. Annual energy cost per person varied from $209 (line 7) to $2244 (line 14), a difference of over 10 times. That difference between 2 households in older homes appears mostly due to differences in heating fuel cost (natural gas vs LP) and how much living space per person (300sf vs 975sf). Most energy value per dollar (68, shown for 2 households on lines 16 and 22 in the "kBtu/$" column) occurred where natural gas and electricity were bought from a large urban utility company, where electricity is priced regressively 8 months of the year (i.e. lower marginal price for higher per-month purchases). Lowest energy value per dollar (33, line 17) occurred for a household without access to natural gas, where electricity was bought from a rural electric cooperative utility and wood from a local non-utility supplier.

BTU/sf-dd is a measure of how much total annual energy was purchased divided by the size of the conditioned floor area and the local degree-days. Degree-days (in this survey, both heating and cooling seasonal totals summed) and floor areas are referenced to allow easier analysis and comparison of home and personal energy performance even when structures are different sizes or located in somewhat different climates or climate years. (Read in my 2001 and 2002 survey reports for more detailed discussion about this rating category.) The best climate-adjusted energy usage per square foot of living space was 2.14 Btu/sf-dd (line 17), about 10.5 times lower than the worst performance of 22.58 Btu/sf-dd (line 16). Best and worst in this category are both 2-person households. Interestingly, the best rating occurred where the owners received the least raw energy per dollar and enjoyed the most living space per person among 2-person households in this survey. It should be disclosed that the 2.14 Btu/sf-dd home is also an intentional super-efficient design by this author which has performed consistently best in this per-sf category in all past surveys.

KBTU/p-dd is a measure of total energy purchased divided by the number of occupants served by that energy and the local degree-days (heating and cooling summed). This measurement allows climate-corrected comparisons of per-person energy use year to year or climate to climate, but does not consider how much living space is used per person. This measurement is useful to offset the bias which appears to favor lower occupant density in the above BTU/sf-dd measurement. The lowest climate-adjusted energy usage per person was 1.87 Btu/p-dd (line 12), almost one-ninth of the highest usage of 16.37 Btu/p-dd (line 16). The lowest usage per-person household had 4 occupants in a 1350 sf home with only moderate thermal efficiency. This 338 sf per person "high density occupancy" contrasts dramatically with the 2000 sf per person "low density occupancy" of the 2-person household leading the per-sf rating category, where per-person energy use was 4.29 Btu/p-dd, about 2.5 times higher. Interestingly, the leading per-person household of 4 used about 2.5 times more energy per sf than the leading per-sf household. This comparison between these 2 category leaders demonstrates (1) that larger homes with low occupant density often have higher per-person energy use regardless of energy efficiency features because there is so much space-conditioning cost per fewer person, and (2) that high occupant density homes with fewer or no energy efficiency features can achieve very low per-person usage because their smaller-space conditioning energy is divided between more persons.

Table 1. Household Energy Data

	Occupants	Flr SF	Conventional Energy Types	EE-AE Measures	County STATE	Total Annual Energy					Energy Use Based On Floor Area & Climate			Energy Use Based On Occupancy & Climate			Daily CO2 Demand	Daily Water Use
	Occupants	Flr SF	Conventional Energy Types	EE-AE Measures	County STATE	Total Annual Energy					Energy Use Based On Floor Area & Climate			Energy Use Based On Occupancy & Climate			Daily CO2 Demand	Daily Water Use
						$	$/person	$/sf	kBtu	kBtu/$	kBtu/sf	Btu/sf-dd	Rating	MBtu/p	kBtu/p-dd	Rating	Lbs/person	Gal/Person
1	6	3744	Elec, Ngas, Wood	BEFIST	Hamilton OH				186606		49.8	7.63	Efficient	31.1	4.76	Efficient	19	72
2	4	1834	Elec, Ngas	F	Kenton KY	1735.64	433.91	0.95	112156	65	61.2	9.36	Efficient	28.0	4.29	Efficient	20
3	4	2000	Elec, Ngas	CLN	Hamilton OH	2114.00	528.50	1.06	109839	52	54.9	9.29	Efficient	27.5	4.65	Efficient	14	28
4	2	1800	Elec, Wood	BFILNPSTU	Hamilton OH	1396.39	698.19	0.78	75870	54	42.1	6.45	Efficient	37.9	5.81	Efficient	48	154
5	2	1680	Elec, LP, Wood	LPI	Warren OH	2483.56	1241.78	1.48	123662	50	73.6	11.27	Average	61.8	9.46	Average	60	63
6	2	2100	Elec, Pellets	AEFHPST	Dearborn IN	1214.26	607.13	0.58	54855	45	26.1	4.00	Super	27.4	4.20	Efficient	30	45
7	4	1200	Elec, Ngas	CFHL	Hamilton OH	838.91	209.73	0.70	50306	60	41.9	6.42	Efficient	12.6	1.92	Super	8
8	2	2622	Elec	EFLT	Hamilton OH	1153.36	576.68	0.44	54102	47	20.6	3.16	Super	27.1	4.14	Efficient	46	74
9	4	3058	Elec, Ngas	BEFHPST	Hamilton OH	1222.40	305.60	0.40	67743	55	22.2	3.39	Super	16.9	2.59	Super	15	37
10	5	3450	Elec, Ngas	BFH	Boone KY	2252.00	450.40	0.65	124634	55	36.1	5.53	Efficient	24.9	3.81	Super	24	49
11	2	3456	Elec, Ngas	EFH	Hamilton OH	1392.49	696.25	0.40	86567	62	25.0	3.83	Super	43.3	6.62	Efficient	31	93
12	4	1350	Elec	BFI	Boone KY	905.06	226.27	0.67	48810	54	36.2	5.53	Efficient	12.2	1.87	Super	21
13	2	1840	Elec, Ngas	EFHIT	Clermont OH	1718.00	859.00	0.93	106352	62	57.8	8.85	Efficient	53.2	8.14	Average	41	41
14	1	975	Elec, LP, Wood	DEHNW	Clermont OH	2244.62	2244.62	2.30	96919	43	99.4	15.21	Inefficient	96.9	14.83	Inefficient	75	24
15	3	1000	Elec	BCFIL	Clermont OH	1122.00	374.00	1.12	45259	40	45.3	6.93	Efficient	15.1	2.31	Super	25
16	2	1450	Elec, Ngas	EI	Hamilton OH	3157.00	1578.50	2.18	213888	68	147.5	22.58	Inefficient	106.9	16.37	Inefficient	69
17	2	4000	Elec, Wood	BEFHST	Butler OH	1706.00	853.00	0.43	56046	33	14.0	2.14	Super	28.0	4.29	Efficient	45	80
18	2	2100	Elec, Wood	BEFHILPSTV	Kenton KY	891.52	445.76	0.42	51323	58	24.4	3.74	Super	25.7	3.93	Super	27	40
19	2	2750	Elec, Wood	BEHPSTW	Hamilton OH	1248.46	624.23	0.45	82349	66	29.9	4.58	Super	41.2	6.30	Efficient	54	3
20	1	2250	Elec, Ngas	BCEHLW	Franklin OH	1560.30	1560.30	0.69	83869	54	37.3	5.95	Efficient	83.9	13.40	Inefficient	84	252
21	2	2692	Elec, Ngas	BFHIL	Franklin OH	1941.00	970.50	0.72	101323	52	37.6	6.01	Efficient	50.7	8.09	Average	32	47
22	4	1664	Elec, Ngas	FH	Hamilton OH	2266.99	566.75	1.36	155230	68	93.3	14.28	Average	38.8	5.94	Efficient	24
23	3	3000	Elec, Oil	BDFL	Warren OH	2473.10	824.37	0.82	125578	51	41.9	6.41	Efficient	41.9	6.41	Efficient	43	49

Table 2. EE/AE: Energy Efficiency & Alternate Energy Features

A	Active solar	L	Landscape for shade, food and/or windbreak
B	Bermed Living Spaces	N	No Furnace or AC, either or both
C	No clothes dryer	P	Passive solar
D	No dishwasher	S	Superinsulated
E	Efficient Appliances	T	Airtightened
F	Fluorescent lamps	U	Underground
H	Efficient HVAC System	V	PVs
I	Income-produced at/from home	W	Home Water Supply (roof-fed, well, etc.)

Ratings of super, efficient, average and inefficient were assigned to each of the two climate-adjusted energy use performance categories based on the following scales:

Btu/sf-dd		kBtu/p-dd
0-5 Super		0-3.95 Super
5-10 Efficient		3.96-7.90 Efficient
10-15 Average		7.91-11.86 Average
15- Inefficient		11.87- Inefficient

Read in my 2001 and 2002 survey reports for more detailed discussion of how this ratings scale developed.

Among the energy categories, one household (line 9) achieved lowest per-sf energy cost as well as "Super" rating in both the per-sf and per-person climate-adjusted categories. This home was intentionally designed for superior energy performance by this author. For the first time in my surveys, this author's retrofitted older home also achieved "Super" in both climate-adjusted categories, with energy cost per sf only 2 cents higher, 42 cents. No other homes achieved "Super" in both categories.

I should point out that the household on line 16, which scored worst in both climate-adjusted energy usage categories, volunteered its energy data as it prepared for major energy retrofits of its older home aimed at substantially reducing energy consumption and increasing use of renewables. Homeowners are welcome and encouraged to use this annual survey to determine their baselines and track their progress as they wrestle down their energy use and cost. This author also uses this survey similarly, watching even his own utility energy use decline year after year since his own retrofits began in 2000. Since no names are mentioned in survey presentations, no need to worry about loss of privacy!

New 2005 survey category for CO2 emissions demand produced interesting results, especially since this survey is being published so soon after SIERRA magazine's article suggesting that sustainable CO2 emissions might be 9 lbs per person per day. In this survey, I use the term "emissions demand' to fairly include emissions produced outside the home for the direct benefit of the household, as when an electric utility burns coal and natural gas to generate electricity. To determine full per-person CO2 responsibility, one would need at least to add emissions per person from workplaces and personal transportation, both beyond the scope of this survey. The lowest home-based CO2 demand per person was the household on line 7 which also scored the lowest energy cost per person. Its 8 lbs of CO2/person-day was less than 10% the highest household's score of 84 (line 20). Interestingly, both highest and lowest scores in this category were for households in homes serviced by both low-CO2 natural gas and high-CO2 coal-fired electricity. Household #7's clear advantage appeared to be especially low electricity usage coupled with rather high occupant density.

Like last year, my 2005 survey households appear biased toward more efficiency, in that more efficient households likely participated than less efficient homes. This author's assumptions about this are that there is probably more interest in energy efficiency among persons who typically contact Robbins to hear directly about this survey and that least-efficient households are probably less likely to be interested in either energy efficiency or how their efficiency compares with others. Thanks to all who volunteered to participated in this survey!

John F. Robbins, CEM CSDP

3519 Moffett Road

Morningview, KY 41063-8748

Phone: (859) 363-0376

E-mail: johnfrobbins@insightbb.com