Ataxa de infiltraçãoé o fluxo volumétricotaxade ar externo para um edifício, normalmente em pés cúbicos por minuto (CFM) ou litros por segundo (LPS). A troca de artaxa, (I), é o número de trocas de ar no volume interno que ocorrem por hora e tem unidades de 1/h.
Geral
- Abaixo do nível do solo ou espaços internos —— Nenhuma perda ou ganho de infiltração é tomada para salas localizadas abaixo do nível do solo ou espaços internos.
- Os edifícios que não são humidificados não têm carga de aquecimento por infiltração latente.
- As cargas de infiltração sensíveis no inverno serão geralmente de 1/2 a 3 vezes as perdas de calor por condução (em média 1,0 a 2,0 vezes).
Infiltração de aquecimento (vento de 15 mph)
Método de taxa de troca de ar
- Faixa de 0 a 10 CA/h.
- Edifícios comerciais:
- 1,0 CA/h. uma parede exterior
- 1,5 CA/h. duas paredes externas
- 2,0 CA/h. três ou quatro paredes exteriores
- Vestíbulos 3,0 CA/h.
CFM/pés quadrados do método da parede
Faixa de 0 a 1,0 CFM/pé quadrado.
Edifícios apertados 0,1 CFM/pé quadrado.
Edifícios médios 0,3 CFM/pé quadrado.
Edifício com vazamento 0,6 CFM/pé quadrado.
Método de Crack
Faixa de 0,12 a 2,8 CFM/pé. de crack
Média 1,0 CFM/pé. de crack
Infiltração de resfriamento (vento de 7,5 mph)
A infiltração da carga de resfriamento é geralmente ignorada, a menos que sejam necessárias tolerâncias rigorosas no controle de temperatura e umidade.
Os valores de infiltração de resfriamento são geralmente considerados como 1/2 dos valores listados anteriormente para infiltração de aquecimento.
FREQUENTLY ASKED QUESTIONS
No infiltration losses or gains are taken into account for rooms located below grade or interior spaces, as these areas are not directly exposed to outside air. This assumption is based on the fact that air exchange between these spaces and the outdoors is negligible.
Winter sensible infiltration loads will generally be 1.2 to 3 times the conduction heat losses, with an average of 1.0 to 2.0 times. This means that infiltration loads can be a significant contributor to heating loads in buildings, especially in cold climates.
The 15 mph wind speed is a common reference point for estimating infiltration rates in buildings. However, actual wind speeds can vary significantly depending on location and building orientation. As wind speed increases, infiltration rates also increase, leading to greater heat losses and energy consumption.
The Air Change Rate Method estimates infiltration rates based on the number of air changes per hour (AC/hr). For commercial buildings, the range is 0 to 10 AC/hr, with higher rates corresponding to more exterior walls. For example, a building with one exterior wall might have an air change rate of 1.0 AC/hr, while a building with three or four exterior walls might have a rate of 2.0 AC/hr. Vestibules typically have a higher air change rate of 3.0 AC/hr.
The CFM/sq ft of Wall Method estimates infiltration rates based on the flow rate of outside air per unit area of exterior wall. This method provides a more detailed estimate of infiltration rates, taking into account the building’s envelope characteristics. The range for this method is 0 to 1 CFM/sq ft of wall.
Yes, infiltration rates can be used to estimate energy consumption in buildings. By calculating the infiltration rate and air exchange rate, building designers and engineers can estimate the heating and cooling loads required to maintain a comfortable indoor environment. This information can be used to optimize building design, HVAC system sizing, and energy efficiency strategies.
