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The Basic House - Energy Analysis Overview

An energy analysis was done for the house plan to examine the energy consumption of the building. With any energy analysis a start point for comparison is required.

The Building America Benchmark Definition Version 2005 along with recent revisions was used as a template for performance evaluation between the advanced building system (Prototype) and the reference building system (Benchmark). The Benchmark Definition requires hourly building energy simulation.

The Building America Benchmark Protocol is generally consistent with mid 1990’s house construction. Unlike other rating performance systems, the Building America Benchmark includes not only heating, cooling and hot water, (which accounts for roughly 50% of total energy consumption of the home), but also energy consumption from lighting, appliances, and other miscellaneous loads.

The following table highlights the differences between the Building America Benchmark House design characteristics and the Prototype design characteristics that were incorporated into this house design.

Benchmark Prototype

Building Enclosure R-13, 16” oc R-10 Foam Sheathed 2x4 Walls

R-20 Roof Insulation R-20 Foam over Roof Deck

Low E Windows (U=0.79, SHGC=0.65) Low E Windows (U=0.33, SHGC=0.3)

R-12 Raised Floor Insulation R-10 Foam under Floor Framing

BM Airtightness (~5in²/100 sf) BSC BA Airtightness (2.5 in²/100 sf)

Mechanical 6.8 HSPF ASHP 92% AFUE Gas Furnace

10 SEER A/C System 14 SEER Cooling System

R-5 Ducts in attic, 15% Leakage Ducts in Conditioned Space

0.88 EF Electric Tank Hot Water 0.94 EF Electric Hot Water Tank

ASHRAE 62.2 Exhaust Fan ASHRAE 62.2 Ventilation by FanCycler

Appliances and Lights 90% Incandescent Lighting 90% Fluorescent Lighting

Regular Appliances ENERGY STAR Appliances

The simulation program used to run the energy model was EnergyGaugeUSA version 2.42 from the Florida Solar Energy Center.

The areas of consideration fall under three main categories, the Building Enclosure, Mechanical Systems, and Appliances and Lights. A parametric whole house energy analysis was done for the case study house design to illustrate the relative importance of the upgrade strategies in each of the three main areas.

The case study model design achieved a whole house 39.2% energy reduction when compared to the Building America Benchmark.

Table 1: Parametric Analysis Results

Note that the estimated cost of change column is a net change, giving credit back for the replaced components. For example, the Benchmark mechanical system includes standard duct installation, standard efficiency heat pump, and hot water heater. Crediting the standard system, the high efficiency system with more air tight ducting and higher efficiency water heater would add $1000 over the cost of the standard equipment.

On the basis of BTU/sf/yr of site energy, the above calculations yield the following:

Figure 5: Building Section

Drainage
Air Barrier

Vapor Management
Thermal Resistance

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Designs That Work Hot-Humid Climate

The Basic House - Energy Analysis Overview

Designs That Work
Hot-Humid Climate